Reactivity of Ferrocenyl Phosphates Bearing (Hetero-)Aromatics and [3]Ferrocenophanes toward Anionic Phospho-Fries Rearrangements

Article

pubs.acs.org/joc

Reactivity of Ferrocenyl Phosphates Bearing (Hetero-)Aromatics and

[3]Ferrocenophanes toward Anionic Phospho-Fries Rearrangements

Marcus Korb, Steve W. Lehrich, and Heinrich Lang*

Faculty of Natural Sciences, Institute of Chemistry, Inorganic Chemistry, Technische Universitat Chemnitz, D-09107 Chemnitz,

̈

Germany

S

* Supporting Information

ABSTRACT: The temperature-dependent behavior within anionic phospho-Fries rearrange-

ments (apFr) of P(O)(OFc)_n(EAr)_3−n(Fc = Fe(η⁵-C₅H₅)(η⁵-C₅H₄); E = O; Ar = phenyl,

naphthyls, (R)-BINOL, [3]ferrocenophanyl; E = N, 1H-pyrrolyl, 1H-indolyl, 9H-carbazolyl; n

= 1−3) is reported. While Fc undergoes one, the Ph-based apFr depends on temperature.

First, the aryls are lithiated and rearranged, followed by Fc and N-heterocycles. Addition of

Me₂SO₄thus gave methylated Fc, contrary to non-organometallic aromatics giving mixtures of

HO and MeO derivatives. The (R)-BINOL Fc phosphate gave Fc-rearranged phosphonate in

91% de. Exchanging O- with N-aliphatics prevented apFr, due to higher electron density at P.

Also 1,2-N→C migrations were observed. X-ray analysis conﬁrms 1D H bridge bonds for OH

and NH derivatives. The diﬀerences in reactivity between N-aliphatic and N-aromatic

phosphoramidates were veriﬁed by electrochemistry. The redox potentials revealed lower

values for the electron-rich aliphatics, showing no apFr, preventing a nucleophilic attack at P

after lithiation. Redox separations for multiple Fc molecules are based on electrostatic

interactions.

Until now, anionic phospho-, thia-, sila-, and carbo-Fries

rearrangements concentrated on rearrangements at the same

type of heteroatom-bonded aromatics within one molecule,

such as phenyls/naphthyls,¹³tricarbonylchromium-complexed

compounds,¹⁴and ferrocenes.¹⁵It was found that molecules

containing more than one O-bonded aromatic unit rearrange

within one reaction step, as shown for phosphates¹⁶and

phosphonates.^12,17A similar reactivity is observed for non-Fries

1,3-S→C shifts that are also known to proceed at ferrocenes.¹⁸

Anionic-induced rearrangements solely proceed at X-bonded

(X = O, N) aromatics, whereas for X = C, an ortho-lithiation

and no subsequent intramolecular migration occur, such as for

arylsulfonamides.¹⁹⁻²¹Stable C-bonded aromatics including

phosphine oxides are solely attacked by singlet oxygen²²or

under basic conditions at >200 °C.²³

Besides OH and SH functionalities, ortho-NH substituents

are also accessible by 1,2-N→C rearrangements to the α-

position as it could be shown for pyrroles.^24,25If the α-positions

are blocked, then 1,3-²⁶or 1,5-migrations occurred.²⁷The less

stable N−P bond, compared to O−P or C−P units, readily

allows 1,2-migrations in the presence of aldehydes,^28,29

aziridines,³⁰oximes,³¹and even pyrroles.²⁵

INTRODUCTION

■

Anionic phospho-Fries rearrangements (apFr) are crucial

reactions within the synthesis of ortho-hydroxyl-functionalized

aromatics.^1,2They proceed regioselectively, which is beneﬁcial

especially within the synthesis of natural products.³The

selectivity is caused by the low reaction temperatures,

compared to cationic alternative synthetic methodologies.⁴

Particularly, the use of phosphorus-containing groups, as the

1,3-O→C migrating fragments, enables their conversion to

phosphines, which are otherwise diﬃcult to prepare.⁵Thereby,

it is beneﬁcial that a chiral phosphorus group rearranges under

retention.⁶The resulting ortho-oxygen functionalities enhance

the catalytic activity by acting as hemilabile bidendate ligands

within, for example, the Suzuki−Miyaura C−C cross-coupling

reaction.^5,7Chiral BINOL backbones, containing an ortho-

hydroxy phosphine oxide substitution pattern, for example,

catalyze asymmetric additions of ZnEt₂to aldehydes, giving the

respective alcohols in up to 99% ee.⁸The ﬁrst anionic phospho

modiﬁcation was reported by Melvin in 1981 by converting

O,O′-dialkyl-O″-aryl phosphates into O,O′-dialkylarylphospho-

nates.⁹We successfully adopted this 1,3-O→C migration on

diﬀerent ferrocenyl-based organometallic compounds,^2,5,10

whereby the highest yields were obtained for phosphates as

the starting materials. The usage of ferrocenyl phosphates

derived from chiral-pool-based alcohols allowed a diastereose-

lective process and gave products with up to 96% de.¹¹

Recently, the progress of anionic phospho-Fries rearrangements

was summarized and showed the great applicability and

regioselective aspects of the rearrangement.^1,12

Investigations of mixed X = O-, N-bonded compounds (e.g.,

O,O′-bonded bridging BINOLS,³²ephedrine-based compound-

s,^1a,33N-phenyltetrazoles,³⁴and 2,8-dimethylphenoxaphos-

phine³⁵) revealed that only the O-phenyl substituents under-

went anionic-induced rearrangements.

Received: January 13, 2017

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The reported examples of rearrangements proceeding at

diﬀerent types of aromatics within one molecule are

summarized in Scheme 1. Electronically and chemically similar

included to estimate the minimum temperature required for

the ﬁrst lithiation process. The dependency between electron

density and reactivity is evidenced by electrochemical

investigations, whereby the ferrocenyl unit is well-suited as a

probe.¹⁰

Scheme 1. Examples of Recently Reported Migrations of

Diﬀerently Substituted Phosphates: (A) Simultaneous

Rearrangement for Phenyl vs Tolyl^16fand (B) Consecutive

Rearrangement of O- vs N-Bonded Phenyls^3b,36

RESULTS AND DISCUSSION

■

The ferrocenyl phosphates 3−7 were synthesized by reacting

lithiated ferrocenol 1-Li with POCl₃(2a) or chlorophosphates

Cl₂P(O)(OR) (2b−2e) (Scheme 2). The usage of BuLi as the

Scheme 2. Synthesis of Ferrocenyl Phosphates 3−8*

*

Conditions: (i) Et₂O (3−5)²/THF (6−8), −30 °C, BuLi, −70 °C,

0.33 equiv of 2a, 0.5 equiv of 2b,d−f, or 1 equiv of 2c. Yields are based

on 2 (3, 4, 7) or 1 (5, 6). Instead of 8, 3 was formed in 58% yield.

a

metalation reagent, instead of widely used nitrogen bases,

increased the yield, that is for 3 from 36^38,39to 92% and for 5

from 62 to 99%⁵(Scheme 2, Experimental Section). However,

the reaction of 1-Li with the 3-hydroxypyridyl derivative 2f did

not result in desired phosphate 8, but rather gave 3 in 58

(tetrahydrofuran) or 25% yield (diethyl ether), showing that

the solvent plays a crucial role within the appropriate reaction.

Although a 2:1 ratio of 1/2f was present, the 3-hydroxypyridyl

substituent was replaced by a third nucleophilic substitution of

1-Li. The properties of R³as the leaving group are due to the

excellent stabilization of a negative charge within the electron-

poor heterocycle. The formation of a keto-amino tautomeric

structure, as possible for the 2- and 4-hydroxypyridine, is

excluded, and thus, a P−N formation is rather disfavored

compared to a P−O bonding of the pyridine derivative.

Nevertheless, pyridyl triﬂates have been investigated for anionic

1,3-O→C migrations. The electron-withdrawing character and

their diﬀerent chemical structure increase their stability toward

the attack of a nucleophile.⁴⁰

substituents, such as phenyl and p-tolyl (reaction A), Scheme

1), rearrange within one reaction step without any reactivity

diﬀerences between both groups.^16fIn compounds bearing

both O- and N-bonded aromatics, the ﬁrst lithiation and 1,3-

X→C migration take place at the O-bonded substituent

(reaction B, Scheme 1).^3b,36Using excess LDA forced the

formation of the phosphane oxide species, however, as a minor

product.

Thus, studies investigating the selectivity of apFr for diﬀerent

substituents are still pending. The widely used reaction

protocols for anionic phospho-Fries rearrangements include

stirring with LDA at −70 °C for 1 h and subsequent warming

of the reaction mixture to ambient temperature, without

knowing whether the reaction occurs at low or high

temperatures.³⁷A comparison between phenyl and the

electronically enriched ferrocenyl groups would allow an

activation energy estimation of the respective groups. Thus,

investigations on triferrocenyl phosphate, (FcO)₃P(O)(3)²(Fc

= Fe(η⁵-C₅H₅)(η⁵-C₅H₄)), which was ﬁrst described by

Herberhold et al. in 1998,^38,39in combination with phenyl,

naphthyl, BINOL, and N-heterocyclic aromatics are reported

herein (Scheme 1C). Temperature-dependent studies are

Treatment of P(O)(OFc)₃(3) (Fc = Fe(η⁵-C₅H₄)(η⁵-

C₅H₅)) with LDA at various temperatures (−70 to 25 °C)

resulted in the expected 1,3-O→C migration of the phosphorus

fragment, which is initialized by an ortho-lithiation, producing 9

and 10 (Scheme 3). After optimizing the reaction conditions

for the apFr of 3², we obtained the highest yield for 9 of 86% at

a temperature of −30 °C. Lower temperatures reduced the

conversion of 3. Above −30 °C, partial decomposition takes

place, lowering the yield. Nevertheless, the double rearranged

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The incomplete reaction of ferrocenyls toward apFr is

contrary to triphenyl phosphate 12, giving phosphine oxide 15

within one reaction step (Scheme 4).^9,16Until now, the apFr of

Scheme 3. Consecutive Anionic Phospho-Fries

Rearrangement of Triferrocenyl Phosphate 3 To Aﬀord

Phosphonate 9 and Phosphinate 10*

Scheme 4. Anionic Phospho-Fries Rearrangement of

Triphenyl Phosphate 12 To Give 13−15*

*

Conditions: (i) THF, LDA, 2 h, H⁺/H₂O. Yields are based on 12.

*

Conditions: (i) LDA, THF, −30 °C, 3 h, Me₂SO₄, 86% (based on 3);

a

b

At −70 °C with 2 equiv of LDA. At −70 °C with 6 equiv of LDA.

(ii) LDA, THF, 0 °C, 3 h, Me₂SO₄, 86% (based on 9).

c

At 0 °C with 12 equiv of LDA.

product 10 was not formed within this reaction step, even using

excess LDA (Scheme 3).

phenyl derivatives were warmed to 0 °C or even ambient

temperature before being terminated with HCl or H₂O.³⁷Thus,

the intermediately formed phosphonates (e.g., 13) and

phosphinates (e.g., 14) have not been isolated and reported

yet. However, adding the scavenger, while keeping the reaction

temperature at −80 °C, allowed the isolation of 13.²Increasing

the temperature, at which the scavenger is added, consecutively

shifts the product ratio from 13 over 14 to 15 at 0 °C. The

identity of 13 was veriﬁed by using single-crystal X-ray

diﬀraction analysis (Figure 3). Initially, lithiation and

An apFr of 9 by treating it with LDA gave phosphinate 10 in

86% yield at 0 °C. The increased temperature required for the

lithiation reaction of 9 is due to the increased electron density

at the ferrocenyl backbone (vide infra). Phosphinate 10 was

formed as a 0.89:0.11 diastereomeric mixture, which was

conﬁrmed by ³¹P{¹H} NMR spectroscopy. Based on an X-ray

measurement (Figure 1), where a similar ratio of two

Figure 1. ORTEP (50% probability level) of the molecular structures

of 9 (left) and 10 (right) with the atom-numbering scheme. All

hydrogen atoms and disordered parts of 10 (10%) have been omitted

for clarity. Intramolecular T-shaped π interactions (blue): Ct−Ct =

4.585(3) Å, α = 72.6(3)° (Ct = centroids of the C₅rings; α = angle

between the respective planes).

Figure 2. ORTEP (50% probability level) of the molecular structures

of 16a (left) and 24 (right) with the atom-numbering scheme. All C-

bonded hydrogen atoms and the disordered parts in 24 (occupancy

ratio of 0.722:0.278) have been omitted for clarity. Intramolecular

hydrogen bridge bond: O3···O4, 2.624(10) Å; O3−H₃O···O4, 153°.

diastereomers was observed, the mainly formed diastereomer

should be assigned as the meso-enantiomers R_p,S_p,r^Pand

S_p,R_p,s^P. The rac-enantiomers R_p,R_p/S_p,S_ponly cocrystallized in

a similar ratio and are reﬁned as a disorder. The meso-isomers

subsequent rearrangement of 12 to form phosphonate 13

occurred at −70 °C. Gradually, increasing the temperature

exceeds the activation energy for the lithiation of 13-Li,

resulting in the formation of phosphinate 14 and ﬁnally

phosphine oxide 15 (Scheme 4). Thus, the number of

rearrangements solely depends on the temperature required

for the lithiation process, due to the absence of any non-

rearranged but ortho-methylated product derived from 12. The

amount of LDA used for the synthesis of 15 was taken from

reported procedures.^9,16

1

should give two sets of signals in the H and ¹³C{¹H} NMR

spectra; however, only one set was present.

However, the formation of phosphine oxide 11 was not

observed because, by the reaction of 10 with LDA at −10 °C,

the starting material could be recovered in 86% yield. In

contrast, when the reaction was run at 50 °C, the educt 10 was

not present and probably decomposed during the course of the

reaction or by a nucleophilic attack at the phosphorus atom.

Obviously, the phenylic hydroxyl groups in 13-Li and 14-Li₂

do not prevent a further deprotonation by LDA. Contrary,

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starting at 3, the presence of already one ferrocenylic hydroxyl

group in 9-Li inhibits further lithiation to 10 with even a 6-fold

excess of LDA (Scheme 3). To complex the lithium ions by

phenyl- instead of ferrocenyl-based hydroxyls, 12 equiv of

PhOLi was added, which increased the yield of 10 from 0 to

46% and the de from 0.77 to 0.99.

due to the presence of 4-ortho-hydrogens in contrast to 2-ortho-

hydrogen atoms at the phenyl groups. As a consequence of the

diﬀerent behavior of ferrocenyl (stepwise) and phenyl groups

(temperature-dependent), phosphinate 18 was formed at 0 °C

as the ﬁnal rearranged product. In contrast, 5 gave phosphine

oxide 22 at 0 °C (Scheme 6), although excess LDA was used.

To prevent the decomposition of oxygen-sensitive hydroxy

ferrocenes,^{2,5,10,11,15,41}the lithiation and rearrangement reac-

tions were quenched by the addition of excess Me₂SO₄,

resulting in the methylation of all ferrocenyl-related hydroxy

functionalities. However, the in situ methylation of phenols is

rather slow and, moreover, gave mixtures of the methylated and

non-methylated derivatives, 16, 18, and 20−22 (Schemes 5 and

6). For phosphine oxide 22, a kinetic resolution was observed

(Scheme 6). Most likely 22a was initially formed as a racemic

mixture (R_p/S_penantiomers), due to the absence of external

and internal chiral information. For 22b (>85% de), one set of

If both phenyl and ferrocenyl groups are present in a

phosphate, as shown for 4 (Scheme 5) and 5 (Scheme 6), the

Scheme 5. Anionic Phospho-Fries Rearrangement of

Diferrocenylphenyl Phosphate 4 To Aﬀord Phosphonates

16a,b and 17 and Phosphinate 18a,b*

1

signals was observed in the H, ¹³C{¹H} and ³¹P{¹H} NMR

spectra, conﬁrming the diastereoselective process. The absolute

conﬁguration could be assigned as S_p,S^P/R_p,R^Pby single-crystal

X-ray diﬀraction analysis (Figure 3).

The diﬀerences between ferrocenyls and phenyls toward

apFr prompted us to extend the substrate scope to condensed

aromatics, which also allows us to investigate the regioselec-

tivity of the 1,3-O→C migrations. To reduce the number of

possible rearrangement products, phosphates bearing two

ferrocenyls instead of one ferrocenyl were applied.

The anionic phospho-Fries rearrangement of 1-naphthyl

derivative 6 resulted in the formation of a 1,2-substitution

pattern, both at the naphthyl and at the ferrocenyl moieties,

giving phosphonate 23 and phosphinate 24, respectively, as

shown in Scheme 7. Phosphinate 24 was formed in a scalemic

mixture (ratio of both diastereomers of 1:0.78), as it was

observed for 18 (Scheme 5). Similar to triferrocenyl 3 and

diferrocenyl phosphate 4, the lithiation of 6 required higher

temperatures. Thus, 90% of the starting material 6 was

recovered at −70 °C.

*

Conditions: (i) THF, LDA (4 equiv), −60 °C, Me₂SO₄. Yields are

a

based on 4. At 0 °C with 7 equiv of LDA.

Replacement of the 1-naphthyl derivative 6 (Scheme 7) with

its 2-isomer 7 (Scheme 8), however, allowed the anionic

phospho-Fries rearrangement at −80 °C (Scheme 8,

Experimental Section). Thus, phosphonate 25 reveals an

increased reactivity toward the lithiation process at the 2-

position of the naphthyl moiety when compared with that of

the 1-substituted compound 6. Lithiation selectively occurred at

the more acidic 3-position and not at the electronically richer 1-

position, which is in accordance with similar rearrangements of

2-naphthyl alkyl phosphonates and phosphates, where the 2,3-

substitution pattern was present in the predominantly formed

products.^21,42If the reaction temperature is increased to 0 °C,

the 1,3-O→C migration occurred at both types of aromatics,

resulting in 26 with a 26a/26b ratio of 1:0.43 (Scheme 8,

Experimental Section). Within this reaction, the phosphonate

25 could not be isolated.

Figure 3. ORTEP (50% probability level) of the molecular structures

of 13 (left) and 22b (right) with their atom-numbering scheme and

the intramolecular hydrogen bridge bond (blue). All C-bonded

hydrogen atoms and the disordered C₅H₅unit in 22b (occupancy ratio

of 0.73:0.27) have been omitted for clarity. Symmetry operation for

generating equivalent atoms (′): x, −y + 1/2, z. Intramolecular

hydrogen bridge bond: O3···O4, 2.597(2) Å; O3−H₃A···O4, 157°.

reactivity toward the lithiation and subsequent 1,3-O→C

migration is reduced compared to that of 12 (recovered

starting materials: 0% of 12 at −70 °C; 25% of 4 at −60 °C,

80% at −75 °C; 0% of 5 at −70 °C, 25% at −80 °C).

In general, the rearrangement at the phenyl rings is favored

compared to that at the ferrocenyls, as clariﬁed by the higher

yields of 16 and 19 at lower temperatures when compared to

the rearrangement products 9, 17, 19, and 20−22.²However,

the formation of 17 indicates a low-energy diﬀerence between

lithiation at a phenyl and a ferrocenyl fragment. Furthermore,

the possibility of an ortho-lithiation is higher at the ferrocenyls,

Phosphonate 27a^38,39was obtained by the reaction of

lithiated 1,1′-ferrocenediol (1,1′-Fc(OLi)₂; 29-Li₂) with POCl₃

and subsequent addition of 1-Li (Scheme 11). However, 27a

was only produced in a yield of 20%, which is attributed to the

reaction protocol applied (vide infra, Experimental Section).

Phosphate (R)-27b, possessing a chiral (R)-BINOL bridging

backbone, was accessible by treatment of 1-Li with

chlorophosphate (R)-2g (Scheme 9).

After appropriate workup, (R)-27b could be isolated in a

yield of 49% (Scheme 9, Experimental Section). It was found

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Scheme 6. Anionic Phospho-Fries Rearrangement of Ferrocenyldiphenyl Phosphate 5 To Give Phosphonate 19, Phosphinates

20 and 21a,b, and Phosphine Oxides 22a,b*

*

a

Conditions: (i) THF, LDA (8 equiv), −70 °C, 2 h; (ii) addition of Me₂SO₄(12 equiv). Yields are based on 5. At 0 °C.

Scheme 7. Anionic Phospho-Fries Rearrangement of

Diferrocenyl(1-naphthyl) Phosphate 6 To Give Phosphonate

23 and Phosphinate 24*

Scheme 9. Anionic Phospho-Fries Rearrangement of

Phosphates 27a and (R)-BINOL-Based (R)-27b*

*

Conditions: (i) THF, LDA (6 equiv), 0 °C, 2 h, Me₂SO₄(8 equiv).

Yields are based on 6.

*

Conditions: (i) 27a/29, BuLi (2 equiv), POCl₃, THF, 1-Li, yield

based on 29; 27b, 1, BuLi (1 equiv), Et₂O, P(O)Cl((R)-BINOL)

(2g), yield based on 1; (ii) THF, LDA, −10 °C (28a)/−70 °C (28b),

2 h, Me₂SO₄, yields are based on 27a/27b.

Scheme 8. Anionic Phospho-Fries Rearrangement of

Diferrocenyl(2-naphthyl) Phosphate 7 To Give Phosphonate

25 and Phosphinates 26a,b*

equiv) at −70 °C allowed anionic phospho-Fries rearrange-

ments at the single substituted ferrocenyls. The formation of

compounds that were lithiated at the bridging backbones of

27a,b were not observed, which is in accordance with the result

obtained with the phenyl derivative of 27b.³²

The non-rotatable PO bond prevents a stabilization of the

negative charge in the 3-position of the naphthyl ring.

Therefore, an attack at the phosphorus atom is excluded.

Phosphonate 28a (Scheme 9) was isolated in virtually

quantitative yield.

The chiral information in the backbone of 27b resulted in a

diastereoselective lithiation, owing to a preferable rotation of

the PO building block to one site of the ferrocenyl unit.

After subsequent 1,3-O→C migration, phosphonate 28b was

isolated as the (R,R_p) diastereomer with a de of 91%, as

conﬁrmed by single-crystal X-ray diﬀraction (Figure 4) in 57%

yield. Within this reaction, 38% of the starting material (R)-27b

could be recovered. Increasing the temperature to −20 °C for 2

h reduced the yield of (R,R_p)-28b to 37%, whereas the de

remained at 89%. Thus, the PO is directed to one site of

cyclopentadienyl, where the lithiation occurred.

*

Conditions: (i) THF, LDA (6 equiv), −80 °C, 2 h, Me₂SO₄(8

a

equiv). Yields are based on 7. At 0 °C.

that the addition of 2 equiv of POCl₃within the synthesis of

(R)-2g did not result in the formation of a bisphosphorylated

BINOL. Treatment of phosphates 27a,b with excess LDA (6

To force metalation at the 1,3-dioxa[3]ferrocenophane

backbone, phosphate (1R)-30 was synthesized by reacting

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Within the synthesis of (1R)-30, the formation of a

[3,3]ferrocenophane, containing two phosphate bridged

ferrocenyls, was not observed. Treatment of (1R)-30 with the

sterically demanding base LiTMP (TMP = tetramethylpiper-

idide) at −10 °C resulted only in the ortho-lithiation at both

cyclopentadienyls. Subsequent addition of Me₂SO₄gave the

1,1′-double-methylated phosphate 31 (Scheme 10). This ansa-

compound was obtained as a mixture of three non-separable

diastereomers in a ratio of 1:0.25:0.3. Single-crystal X-ray

diﬀraction analysis allowed the determination of the absolute

conﬁguration of one diastereomer, which could be assigned to

(1R,R_p,S_p,s^P) containing a pseudochiral phosphorus atom

(Figure 5). We assume that the (1R,R_p,S_p,s^P)-31 isomer is the

main diastereomer formed within this reaction. This can be

explained by the steric hindrance of the two methyl groups at

C3 at one site of the ferrocenyl backbone, as shown in the

crystal packing (Figure 5). Furthermore, the PO bond is

ﬁxed at one site and favors a pseudo-meso-lithiation. However,

the absolute conﬁguration of the other two diastereomers could

not be unequivocally determined. Most likely the pseudo-

racemic (R_p,R_p) and (S_p,S_p) isomers were formed since their

ratio within the product mixture is similar (Experimental

Section). Increasing the temperature within the reaction of

(1R)-30 with LDA to ambient conditions did not change the dr

of (1R)-31, whereby the amount of the recovered starting

material (1R)-30 increased from 0 to 6%. This can be explained

by the deprotonation and cleavage of tetrahydrofuran.^5,43The

addition of the methylation reagent Me₂SO₄also resulted in an

activation of the PO bond, which favors a nucleophilic attack

of water during the workup procedure and hence the cleavage

of the ferrocenophane. Methylation of the thus-formed 1′-

hydroxy moiety gave (1R)-32 as a racemic mixture concerning

the conﬁguration of the phosphorus atom. Additionally, 20% of

1,1′-Fc(OMe)₂was isolated, indicating hydrolysis of the

[3]ferrocenophane backbone of (1R)-30.

Figure 4. ORTEP (50% probability level) of the molecular structures

of 26b (left) and (R,R_p)-28b (right) with the atom-numbering

scheme. All hydrogen atoms and one molecule of CHCl₃(28b) have

been omitted for clarity.

(Li)₂-29 with the chiral dichloro (1R)-α-fenchyl phosphate

(2h),¹¹whereby the aliphatic substituent does not undergo

lithiation reactions (Scheme 10). The fenchyl methyl groups in

Scheme 10. Anionic Phospho-Fries Rearrangement of the

Chiral-Pool-Based Phosphate (1R)-30*

The usage of ferrocene diol 29 could allow for the

consecutive preparation of the super-ferrocenophane 35 as

depicted in Scheme 11. In this respect, 29 was metalated by

using BuLi and the thus-formed corresponding lithiated species

gave 29-P₂O₂Cl₄with 2 equiv of POCl₃. It was expected that

the stepwise addition of (Li)₂-29 to the latter compound should

result in the formation of phosphate 35. However, instead, only

12% of the bis[3]ferrocenophane 34 could be isolated (Scheme

11). To investigate if the intermediate bisphosphate 29-

P₂O₂Cl₄or a mixture of the 1,3-dioxa[3]ferrocenophane 29-

POCl and POCl₃was formed, 1-Li was added instead of (Li)₂-

29. After appropriate workup, 3 (42%), 27a (20%), and

bisphosphate 33 (11%) could be isolated, revealing that the

respective reaction mixture contained POCl₃, 29-P₂O₂Cl₄, and

29-POCl. The ratio of 3/27a/33 also indicated that 29-POCl

was predominantly formed.

*

Conditions: (i) BuLi, Cl₂P(O)((1R)-α-Fn) (2h), Et₂O. Yield based

on 29; (ii) THF, LiTMP, −10 °C, Me₂SO₄. Yields are based on (R)-

30. Stirring for 18 h at ambient temperature; formation of 31 in 53%

yield, 1,1′-Fc(OMe)₂in 20% yield, formation of 32 in 10% yield; rac

refers to the conﬁguration at the phosphorus atom.

a

Treatment of 33 with LDA at −30 °C resulted in complete

decomposition of this compound by producing an insoluble

residue during column chromatographic workup. In contrast,

bis[3]ferrocenophane 34 gave the double rearranged bi-

sphosphonate 36, which was isolated in a yield of 62%

(Scheme 11, Experimental Section). Compared to previous

results of anionic phospho-^5,11and thia-Fries^15brearrange-

ments, the meso-(R_p,S_p)-isomer should be exclusively formed.

Since investigations about apFr at phosphoramidates are

pending, compounds 37−41 with P−N bonds were studied.

The family of organophosphorus Fc−O−P−N compounds⁴⁴

has sparsely been investigated, including four-membered

Figure 5. ORTEP of the two crystallographically independent

molecules of the asymmetric unit of (1R-α,R_p,S_p,s^P)-31 (left, 50%

probability level) and 52 (right, 30% probability level) with the atom-

numbering scheme. All C-bonded hydrogen atoms have been omitted

for clarity.

the 1- and 3-positions of the bicycle enhance the stereo-

selectivity within such types of reactions, when compared to

other chiral pool alcohols (Scheme 10).¹¹

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Scheme 11. Reaction of 29 with POCl₃and/or FcOLi for the Synthesis of [3]Ferrocenophanes 27a and 34 and Phosphate 33

(Yields Are Based on 29)*

*

a

b

Conditions: (i) THF, LDA (4 equiv), −30 °C, 2 h, Me₂SO₄(8 equiv). Yield based on 1. Yield based on 34.

Scheme 12. Synthesis of Ferrocenyl Phosphoramidates 37−41 and Their Treatment with s-BuLi (Yields Are Based on 37−41)*

*

a

b

Conditions: (i) NEt₃(37, 38, 40, 41)/BuLi (39), 2i−l, [BH₃·THF] (37, 40)/S₈(38). Yields are based on 1. THF, ≤−10 °C, 3.5 h. Hexane,

c

ambient temperature, 18 h. Et₂O, ≤−30 °C, 4 h.

diazadiphosphetidine cycles³⁹and six- and eight-membered

cyclic phosphazenes.⁴⁵

be conﬁrmed by electrochemical investigations (Figure S3 and

Table 1). Replacing LDA with the stronger base s-BuLi allowed

the synthesis of the ortho-methylated derivatives 42−45

(starting from 37−39). Within these reactions, lithiation

occurred at the ortho-position, whereby the lithium ion is

stabilized by the oxygen atom of the ferrocenyl entity. An

involvement of the P→E moiety is possible for E = O and S;

however, in the case of the borane adduct 43 (E = BH₃), it

failed. Nevertheless, the ortho-methylated species 42−45 could

not be separated from their starting materials 37−39 due to

their similar properties within the column chromatographic

workup. However, they could be identiﬁed by inter alia ¹H and

¹³C{¹H} NMR spectroscopy (vide infra) and are highlighted in

Figures S1 and S2 (also see Experimental Section). The

lithiation behavior strongly depends on the solvent applied, as it

The aliphatic phosphoramidates 39 and 41, thiophosphor-

amidate 38, and borane adducts 37 and 40 were synthesized,

diﬀering between one (40, 41) and two N-bonded substituents

(37−39). They were accessible by the reaction of 1 (in the

presence of a base) with chlorophosphineamines 2i,l,

chloropyrrolidine phosphinate 2j, or the 2-chloro-3-methyl-

1,3,2-oxazaphospholidine 2k (Scheme 12). The P^IIIderivatives

were subsequently treated with either the [BH₃·THF] complex

(37, 40) or S₈(38).

Consecutive treatment of 37−41 with LDA and MeI did not

result in the lithiation of these species, and hence, >80% of the

starting material could be recovered. The high basicity of the

ferrocenyl backbone is caused by an increased electron density,

due to the electron-donating N-bonded substituents, as it could

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Scheme 13. Synthesis of Ferrocenyl Phosphonates 46−48 and Their Treatment with LDA Causing 1,3-O→C and 1,2-N→C

Rearrangements for the Synthesis of 49−54*

*

Conditions: (i) THF, −30 °C, BuLi, 2m−o; yields are based on 1; (ii) THF, LDA (6 equiv), −40 °C, 2 h, Me₂SO₄(8 equiv); yields are based on

a

b

c

46−48. At −70 °C. At −60 °C. At 0 °C.

could be shown for pyrrolidine containing 39. Thus, running

the reaction in hexane gave 44 in a mixture along with 39 and

45 in a ratio of 1:0.24:<0.05, whereas in diethyl ether, a ratio of

1:0.06:0.65 is characteristic, due to the increased reactivity of s-

BuLi. The methyl group should be substituted in the ortho-

position to the oxygen atom (1,2-substitution), due to a

stabilization of the lithium ion, as found for derivatives

possessing a Fc−P bond.⁴⁶To the best of our knowledge,

1,3-disubstituted products can merely be obtained by multiple-

step lithiations including reactions with electrophiles⁴⁷or are

formed in a negligible yield compared to that with the main 1,2-

product.⁴⁸Hence, a 1,3-substitution pattern is rather expected

for electrophilic aromatic substitution reactions and not for

lithiation reactions as depicted in Scheme 12.⁴⁹

The results of the reactivity of N-bonded, aliphatic Fc−O−P

compounds and our previous investigations within this ﬁeld of

chemistry⁵revealed that electron-withdrawing phosphorus

groups increase the possibility of a lithiation and the occurrence

of an apFr. Thus, we replaced the aliphatic by N-bonded

nitrogen heterocycles. The lone pair of the nitrogen is rather

involved in the aromatic system, which decreases the transfer of

electron density to phosphorus and the ferrocenyls. Thus, their

stability toward acidic media is increased.⁵⁰

pyrrole- and indole-based phosphonates are known, whereas

carbazole derivatives are sparsely investigated.⁵¹This is clariﬁed

by reported procedures for the synthesis of 2m−o, of which

only the indolyl derivative 2n has been reported.⁵²Treatment

of lithiated carbazole with excess POCl₃in tetrahydrofuran at

−80 °C resulted in the formation of 2o. In contrast, the

decreased steric demand and thus the increased reactivity of

lithiated pyrrole toward POCl₃required a dropwise addition of

pyrrole into a tetrahydrofuran solution containing >10 equiv of

POCl₃at −80 °C.

In contrast to the aliphatic derivatives 37−41, the reaction of

46−48 with LDA followed by the addition of Me₂SO₄gave

several 1,3-O→C (49−51, 54) anionic phospho-Fries and 1,2-

N→C (52−54) rearranged products (Scheme 13). The latter

ones are the ﬁrst examples of rearrangements of phosphonato

moieties. Shifts at thiaphosphonates,²⁴chiral phosphine oxides,

and sulﬁdes⁶at pyrrole have been reported, whereas indoles

have not been investigated. It should be noted that within the

synthesis of the indole systems 50 and 53, 18% of FcOMe

could also be isolated, probably due to a nucleophilic attack at

the phosphorus atom, combined with the good stabilization of a

negative charge at the heterocycle. The reaction of 46 even

resulted in the formation of 32% of FcOMe and 45% of

recovered starting material at −70 °C, which supports the

assumption of a nucleophilic attack.

Phosphonates 46−48 were accessible by the reaction of 1-Li

with dichlorophosphonates 2m−o, whereby the size of the

aromatic systems increased from 1H-pyrrole (46) to 1H-indole

(47) and 9H-carbazole (48) (Scheme 13). A wide range of

Contrary to the phenyl and naphthyl phosphates 4−7, the

ﬁrst rearrangements occurred at the ferrocenyl substituent,

resulting in the formation of phosphinates 49−51 (Scheme

13). Increasing the temperature to 0 °C accelerated the

rearrangements at the heterocycles, and phosphonates 52 and

53 and phosphinate 54 could be isolated after appropriate

workup. The chemical properties toward lithiation reactions

could also be derived from electrochemical measurements

(Table 1).

The conﬁguration of the predominantly formed diaster-

eomers in 51 could be assigned as R_p,S^P/S_p,R^Pbased on single-

crystal X-ray diﬀraction analysis (Figure 1). Phosphinate 54 was

formed in a ratio of 1:0.098 (0.82 de). It remains unclear

whether the diastereoselective process in the case of 54 is

caused by steric eﬀects of the heterocycle or by a stabilization of

the lithium ions by the aromatic π-system.

Most of the heterocyclic phosphonates and phosphinates

showed no sign of decomposition in solution, except for 49,

which rapidly decomposed due to either a nucleophilic attack at

the phosphorus atom or oxidation reactions occurring at the

pyrrole substituent. Compound 52 was hardly soluble in

Figure 6. ORTEP (50% probability level) of the molecular structures

of 53 (left, 50% probability) and 51 (right, 30% probability level) with

their atom-numbering scheme. All C-bonded hydrogen atoms, the

disordered atoms (occupancy ratio of 0.88:0.12) in 53, one disordered

molecule of CHCl₃in 53, and disordered packing solvent in 51 (0.9·

CH₂Cl₂) have been omitted for clarity.

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CDCl₃, due to the formation of intermolecular hydrogen bridge

bonds, as evidenced from in the crystal packing (Figure S30).

Thus, a mixture of CHCl₃and DMSO was required for NMR

investigations. The structure of 52 could be veriﬁed by single-

crystal X-ray diﬀraction analysis (Figure 5).

and 36 are observed at higher ﬁelds between 109 and 111 ppm

for the C−O−P and 129 and 131 ppm for the C−O−CH₃

fragments.

Phosphates containing three freely rotatable P−O bonds,

which is typical for 3−7 and 33, exhibit ³¹P{¹H} shifts from

−15.3 to −16.9 ppm. N-Aryl phosphonates 46−48, showing a

similar chemical behavior, are slightly downﬁeld shifted to −11

ppm. Replacement of the N-aryl with an N-alkyl substituent, as

characteristic for 41, shifts the signal downﬁeld to 2.5 ppm.

Phosphorus atoms that are included in 1,3-dioxa[3]-

ferrocenophane moieties, in general, showed downﬁeld shifted

³¹P{¹H} resonances compared to non-bridged derivatives.

Thus, the signals for exclusively ferrocenyl-containing 27a

and 34 occurred at −5.6 ppm, at −2.5 ppm for the (R)-BINOL

derivative 27b, and at −4 to 1 ppm for 30 and 31 bearing an

aliphatic (1R)-α-fenchyl substituent. An additional methyl

substituent at the cyclopentadienyl ring, as present in 31,

does not inﬂuence the ³¹P shift compared to their non-

methylated derivative 30. The ³¹P shift also increased from 23

ppm for 39, 44, and 45, bearing two N-alkyl groups, to 91 ppm

for the P = S derivatives 39 and 43 and to 122−132 ppm for

the borane adducts 37, 40, and 42.

NMR Spectroscopy. In the ¹H NMR spectra of all

ferrocene sandwich compounds, an AA′XX′ signal pattern for

3,4

the C₅H₄cyclopentadienyl protons with

J

coupling

H,H

constants of ∼2 Hz⁵³is observed, which is characteristic of

recently reported ferrocenyl phosphates and their rearrange-

ment species (Tables S1 and S2).^2,5,11The assignment of all

resonances is supported by 2D experiments such as COSY,

HSQC, and HMBC that are included in the Supporting

Information. For 24 and 52, ¹³C{¹H} shifts were taken from

HMBC and 90 DEPT measurements, due to their low

solubility. In general, diastereomeric ratios were obtained

from ﬁtted integrals of the ³¹P{¹H} or selected signals in the ¹H

spectra to exclude baseline inaccuracies.

The OCH₃resonances in the 1,3-O→C anionic phospho-

Fries rearranged species 9, 10, 17, 18, 21, 22, 24, 26, 28, 36,

1

49−51, and 54 appeared as singlets in the H NMR spectra

between 3.5 and 4.0 ppm, as expected.^2,5,11

Within the synthesized phosphonates, the ³¹P{¹H} NMR

shift allows a diﬀerentiation between O-/N-bonded non-

bridged (17, 19, 23, 25, 49−51; 14−19 ppm), O-bonded

[3]ferrocenophanes (28a,b, 36; 30−35 ppm), and molecules

bearing a C-bonded N-heterocycles (52, 53; 4.0−4.5 ppm).

The ³¹P{¹H} NMR resonances for phosphinates 10, 14, 18, 20,

21, 24, 26, and 54 range between 25 and 45 ppm. Phosphine

oxides 15 and 22 were observed at 38−51 ppm, whereas a

trend within the presence of an OCH₃or OH group could be

observed. Thus, the comparison of between the a (OH

containing) with the respective b derivatives (OMe instead of

OH) in 16, 18, 21, 26, and oxide 22 reveals Δδ values of 4 ppm

for 16, more than 9 ppm for 18, 21, and 26, and 11 ppm for 22.

This is probably due to the formation of intramolecular

hydrogen bridge bonds that are present in the solid state

(Figures 3 and 4 and Figures S10, S12, S25, and S27), in CDCl₃

involving the PO bond, which lowers the electron density at

the phosphorus atom. Within the series of the dichlorophos-

phates of the N-bonded heterocycles, the ³¹P shifts decrease

from 1H-pyrrol-1-yl (2m, 5.5 ppm) > 1H-indolyl-1-yl (2n, 2.7

ppm) > 9H-carbazol-9-yl (2o, 0.5 ppm), whereas this trend is

not observed for the respective diferrocenyl phosphates 46−48.

The ¹¹B NMR values for the borane adducts 37, 40, and 42

slightly diﬀer between the (NEt₂)₂-functionalized compounds

40 and 42 with −39.5 ppm and the cyclic 2-aminoethanol

containing species 37 (−42.6 ppm). The appropriate signals

In contrast, the respective signal in the (R)-BINOL

phosphonate 28b occurred somewhat high-ﬁeld-shifted at

2.63 ppm. The resonances for the C-bonded methyl groups

in methylated 31 and 42−45 occurred as singlets at ∼2.05 ppm

in the ¹H and at 12−14 ppm in the ¹³C{¹H} NMR spectra. The

coupling pattern and the distribution of the related proton and

carbon resonances of the C₅H₃units support a 1,2-substitution

pattern for 42−45 (vide supra).

Compounds 13−15, 16a, 18a, 19, 20, 21a, 22a,b, 23−25,

and 26a containing OH and 52−54 with NH functionalities

showed signals between 9 and 12 ppm, occurring as singlets or

4

as doublets with a J_H,Pcoupling of ≤1 Hz.

The ¹H NMR resonances of the methyl groups of 32

occurred as a singlet at 3.37 ppm for the C₅H₄(OCH₃)

fragment. In contrast, the P−O−CH₃fragment was observed as

3

a doublet at 3.82 ppm with a J_H,Pcoupling constant of 8.4−

11.3 Hz.

A successful 1,3-O→C migration is evidenced by the

appearance of doublets in the ¹³C{¹H} NMR spectra for

formed C_Fc−P bonds at 51−59 ppm for the phosphonates 9,

17, 28a,b, 36, and 49−53 and 60−63 ppm for the phosphinates

10, 18a,b, 21a,b, 24, 26a,b, and 54 and phosphine oxides 22a,b.

The signals for phenyl-related C_Ph−P units occurred between

100 and 122 ppm, independent of the type of the phosphorus

1

compound. However, the trend of the J_C,Pcoupling constants

follows the order phosphonates (229−206 ppm) > phosphi-

nates (163−184 ppm) > phosphine oxides (111−107 ppm) for

the ferrocenyl-related carbons. Non-ferrocenyl-related C−P

couplings decrease from N-heterocyclic phosphonates (52 and

53; 236−227 ppm) > non-heterocyclic phosphonates (13,

16a,b, 19, 23, and 25; 181−190 ppm) > N-heterocyclic

phosphinates (54; 172 ppm) > non-heterocyclic phosphinates

(14, 18a,b, 20, 21a,b, 24, and 26a,b; 132−147 ppm) >

phosphine oxides 15 and 22 (107−111 ppm) (Tables S1 and

S2).

The ipso-carbon atoms of the C−O−Me and C−O−P

moieties could also be distinguished. Independent from a single

or 1,2-double substitution, the C−O−P carbon atoms appear

between 116 and 119 ppm, whereas the C−O−CH₃groups

occurred downﬁeld shifted at 126−130 ppm. In contrast, the

signals in 1,3-dioxa[3]ferrocenophanes 27a, 28a, 30, 31, 34,

1

appear as doublets with a J_B,Pcoupling constant of ∼90 Hz.

Ferrocene 22b exhibits one signal (>99% de) in the ³¹P{¹H}

1

NMR spectrum at 38.2 ppm and two sets of signals in the H

and ³¹C{¹H} NMR spectra, revealing the formation of two

diastereomers. Therefore, the de could be calculated by using

the integrals of the OCH₃(85% de) and the OH (87% de)

resonances. This leads to the conclusion that the ³¹P resonances

of both diastereomers occurred isochronically.

The methylated ferrocenes 42−45 could be identiﬁed within

their mixtures with their starting materials (18% of 37 for 42,

7% of 38 for 43, and 6% of 39 for 44 and 45; Scheme 12). The

methyl groups were observed at ∼2 ppm in the ¹H and at ∼12

ppm in the ¹³C{¹H} NMR spectra, which are characteristic for

methylferrocene.⁵⁴The The cyclopentadienyl carbons bearing

CH₃groups showed resonances between 74 and 75 ppm. For

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the 2,1′-functionalized ferrocene 45, the additional methyl

group at the 1′-position was observed at 13.9 ppm. The

respective ipso signal of the cyclopentadienyls occurred at 85.0

ppm.

Molecular Solid-State Structures. The molecular struc-

tures of 4, 6, 9, 10, 13, 16a, 22b, 24, 26a, 27a, 28b, 31, 34, 40,

41, 47, 48, and 51−53 in the solid state have been determined

by single-crystal X-ray diﬀraction analysis (Figures 1−6).

Suitable crystals were obtained by crystallization by slowly

cooling hot solutions or by solvent evaporation at ambient

temperature (for more details, see the Experimental Section).

The compounds crystallized in the centrosymmetric triclinic

(S_p,R^P/R_p,S^P), present in solution in a ratio of 1:0.78

(Experimental Section), was, however, not observed.

A diastereoselective crystallization process also occurred in

the case of phosphinate 26b. NMR investigations (vide supra)

revealed a ratio of both diastereomers of 1:0.5, whereas single

crystals of 26b appeared as a mixture of both enantiomers R_p,S^P

and S_p,R^P, respectively, which are the most predominantly

formed conﬁgurations.

Phosphate 31 possesses, similar to meso-10, a pseudochiral

phosphorus atom, due to the diﬀerent conﬁgurations of the

C₅H₃Me moieties, resulting in the (1R-α,R_p,S_p,s^P)-31 isomer.

We conclude that this is the predominantly formed

conﬁguration within the mixture of isomers, based on NMR

investigations, which showed an isomeric mixture of 1:0.25:0.3

(Experimental Section). In the carbazole derivative 51 a dr of

1:0.28 is characteristic, as evidenced by NMR experiments

(vide supra), while single crystals of the R_p,S^P- and S_p,R^P-

conﬁgured molecules were obtained. The kinetic resolution of

22a to 22b within the methylation reaction (Scheme 6)

resulted in the formation of S_p,S^P/R_p,R^Pisomers.

Interestingly, the PO bond in 22b (1.5013(15) Å) is

enlarged compared to the other P^Vcompounds reported herein

(1.441(8)−1.477(2) Å). In the P^IIIspecies 40, the P−B bond

distance is further increased to 1.881(5) Å, which is in the

range of reported structures (1.868−1.899 Å)^58,59for this type

of compound (vide infra).

Compound 26b exhibits the shortest Fe···Cp′ distance of

1.6279(6) Å compared to all other compounds reported herein

(Tables S3 −S5) but is typical for other ferrocenes bearing

phosphole or benzannelated moieties.⁶⁰This is evidenced by

the formation of an intermolecular T-shaped π interaction with

the naphthyl ring of an adjacent molecule, resulting in the

formation of a dimer (Figure S18). This behavior is supported

by a π−π interaction of 3.277(7) Å between the C25 atoms of

adjacent coplanar naphthyl rings (α = 0°).

Ferrocene 28b is the third example of a binaphthyl-related

phosphonate; one has been reported with the same

conﬁguration at the BINOL (R)²⁸and one as the racemic

mixture.⁶¹

The bridging of the BINOL moiety to a phosphepine

structure shifts the oxygen atoms by 0.154(6) (O1) and

0.039(6) Å (O2) out of the C₁₀H₆plane. However, the bending

of the naphthalene entities out of their planarity is rather low

(5.7(4) and 4.4(5)°; Tables S3 −S5). Both planes of the two

naphthyls are rotated by 54.6 (2)°.

Indoles that are not bearing stabilizing substituents in 3-

position are also rarely described in the solid state, that is, one

example of a 1H-indole phosphate/phosphonate with a P−N

bond.⁶²

Furthermore, the molecular structure of a 2-indanone

derivative in the solid state was reported.⁶³Compound 53 is

the ﬁrst example of a molecular solid-state structure of a 1H-

indol bearing a phosphorus moiety in the 2-position.

Additional features in the packing of the solid-state structures

of the compounds described herein are graphically described in

Figures S5−S33 (Supporting Information).

space group P1 (9, 24, 26a, 34, 48, and 51), the monoclinic

̅

space groups P2₁/n (4 and 53), P2₁/c (6, 10, 16a, 22b and 47),

C2/c (41, 52), and the orthorhombic space groups Pnma (13)

and Pbca (40). Ferrocenes 27a, 28b, and 31 crystallized in the

non-centrosymmetric monoclinic space group P2₁(31, abs.

struct. parameter⁵⁵= 0.002(8)) and the orthorhombic space

groups Fdd2 (27a, abs. struct. parameter = −0.01(2)) and

P2₁2₁2₁(28b, abs. struct. parameter = 0.012(16)).

In the asymmetric unit, these compounds are present with

one (4, 6, 9, 10, 16a, 22b, 24, 26a, 27a, 28b, 40, 41, 47, 48, and

51−53) two (31), or one-half (13 and 34) of crystallo-

graphically independent molecule(s). The two molecules of 31

diﬀer by the rotation of the (1R)-α-fenchyl moiety around its

P−O bond, as conﬁrmed by the C1_Fn−C2_Fn−O_Fn−P torsions

of −90.8(4) and −151.6(3)° (Figure S21).

This also explains the favored formation of one diastereomer,

due to this free rotation of the sterically demanding methyl

groups at C3 and also the possibility for lithiation if they are

slightly bended in one direction. In phosphonate 13, a mirror

plane is present in the phenyl plane, including the P1, O2, and

O3 atoms (Figure 3). The formula unit of phosphate 34 can be

calculated by the inversion through the Fe2 atom (Figure S22).

The O−P−O bridge also decreases the Cp···Fe···Cp′ angle

(Cp = C₅H₅; Cp′ = C₅H₄or C₅H₃) from 175.59(4)°, which is

the smallest value found in the MeO-substituted moiety in 9, to

170.41(4)−171.8(10)° in 27a, 31, and 34. These values are in

accordance with 171.1° for the only reported example of a

solid-state structure of an O−P−O-bridged 1,3-dioxa-2-

phospha[3]ferrocenophane.³⁹

In further examples of solid-state structures containing 1,1′-

disubstituted ferrocenes in an O−M−O moiety, the ferrocenyl

backbone acts as a chelating ligand for metals,⁵⁶for compounds

of 1,1′-ferrocenediol and related macrocyclic diethers,⁵⁷

exhibiting signiﬁcantly increased Cp···Fe···Cp′ angles toward

the oxygen coordination site with a minimum of 174.5°.⁵⁶

The bite angle of the 1,1′-substituted ferrocenes strongly

depends on the number of bridging atoms (Supporting

Information).

The absolute conﬁguration of phosphonate 10 of the

predominantly formed diastereomer (0.77 de, Scheme 3)

could be assigned to the pair of the meso-diastereomers R_p,S_p,R^P

and S_p,R_p,S^P(Figure 1). The pair of racemic enantiomers

(R_p,R_p/S_p,S_p) was present in solution (0.89:0.11, Experimental

Section) and cocrystallized (ratio 0.9:0.1), resulting in a

disorder of the structure (omitted in Figure 1).

Electrochemistry. The electrochemical behavior of the

ferrocenyl phosphates 3−7, 27a,b, 30, 31, 33, and 34, the

phosphonates 9 and 28b, the phosphinate 10 (Figure 7 and

Supporting Information Figure S3), and the nitrogen-

containing ferrocenyl phosphoramidates 37−41, 46−48, and

51 were investigated by cyclic voltammetry (CV) and square-

wave voltammetry (SWV). The charge transfer behavior of the

Phosphinate 24 predominantly crystallized as the S_p,S^P

isomer, whereas the disordered part occurred in a R_p,R^P

conﬁguration (ratio of 0.722:0.278). With regard to the

centrosymmetric space group P1, a diastereoselective crystal-

̅

lization of 24 took place. The other set of diastereomers

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Table 1. Cyclic Voltammetry Data of Compounds 3−7, 9,

a

10, 27a,b, 28b, 30, 31, 33, 34, 37−41, 46−48, and 51

b

c

b

c

b

c

d

compound

E₁°′ (ΔE_p)

E₂°′ (ΔE_p)

E₃°′ (ΔE_p)

ΔE°′

3

4

30 (64)

235 (66)

250 (65)

435 (68)

205/200

165

85 (60)

5

106 (60)

85 (60)

6

250 (66)

260 (70)

200 (62)

205 (70)

535 (72)

165

7

90 (68)

170

9

−20 (64)

−60 (66)

110 (62)

142 (64)

152 (68)

302 (64)

254 (60)

90 (70)

520 (76)

510 (80)

220/320

265/305

425

10

27a

27b

28b

30

31

33

34

37

38

39

40

41

46

47

48

51

270 (60)

800 (135)

180/530

315

e

225 (70)

−29 (65)

−50 (62)

−63 (62)

62 (64)

540 (125)

−14 (74)

100 (58)

95 (60)

202 (106)

260 (66)

255 (62)

250 (66)

216

160

250

90 (62)

40 (60)

290 (64)

a

b

All potentials are given in mV. E°′ = formal potential of the

c

respective redox process. ΔE_p= diﬀerence between oxidation and

d

reduction potentials. ΔE°′ = potential diﬀerence between the

ferrocenyl-related redox processes. Potentials vs FcH/FcH⁺, scan

rate of 100 mV s⁻¹at a glassy carbon electrode of 1.0 mmol L⁻¹

solutions in anhydrous dichloromethane containing 0.1 mol L⁻¹of

e

[NⁿBu₄][B(C₆F₅)₄] as supporting electrolyte at 25 °C. Broad two-

electron process.

oxidized products of 3 and 10 were studied in an exemplary

manner in more detail by in situ UV−vis/NIR spectroelectro-

chemistry (Supporting Information, Figure S4). Selected CV

and SWV of individual monoferrocenes are presented in the

Supporting Information (Figure S3).

The CV data are summarized in Table 1. All measured

compounds, except 33 and 34, show for each ferrocenyl moiety

one well-separated reversible one-electron redox event. For

compound 3, with its three OFc units, three separated redox

processes with the ﬁrst one at E₁°′ = 30 mV were found (Figure

7), due to the weak coordinating electrolyte [ⁿBu₄N][B-

(C₆F₅)₄], which is known to stabilize highly charged species

and minimize ion pairing eﬀects.⁶⁴⁻⁶⁶However, this diﬀers

when [ⁿBu₄N][ClO₄] as electrolyte was used, as reported by

Herberhold et al. There, only two reversible events were

observed with a two-electron step for the ﬁrst and a one-

electron step for the second oxidation.³⁸

Figure 7. Cyclic voltammograms (solid lines, scan rate 100 mV s⁻¹)

and square-wave voltammograms (dotted lines, step height 25 mV,

pulse width 5 s, amplitude 5 mV) ferrocenyl phosphates 3, 4, 6, 7, 27a,

33, 34, phosphonate 9, and phosphinate 10 in dichloromethane

solutions (1.0 mmol L⁻¹) at 25 °C using a glassy carbon working

electrode. Supporting electrolyte is 0.1 mol L⁻¹of [NⁿBu₄][B-

(C₆F₅)₄]).

When one ferrocenyl group in 3 is replaced by an electron-

poorer phenyl moiety, as is typical in 4, the ﬁrst redox process is

shifted to a higher redox potential (E₁°′ = 85 mV) (Table 1), as

expected. The same trend is observed for 5 in which two

ferrocenyl moieties are replaced by two phenyl units (E₁°′ =

106 mV) (Table 1). A replacement of the phenyl group in 4 by

a naphthyl moiety, as is characteristic for 6 or 7, however, does

not have any notable inﬂuence on the ﬁrst (4 and 6, E₁°′ = 85

mV; 7, E₁°′ = 90 mV) or second redox potential (4 and 6, E₂°′

= 250 mV; 7, E₂°′ = 260 mV).

The anionic phospho-Fries rearrangement of 3 to give 9 led

to a decrease of the ﬁrst redox potential, due to the more

electron-donating methoxy group, which increases the electron

density at the ferrocenyl (3, E₁°′ = 30 mV; 9, E₁°′ = −20 mV).

A second rearrangement to form compound 10 leads to a

similar reduction of the ﬁrst redox event from E₁°′ = −20 mV

(9) to E₁°′ = −60 mV (10), whereas the second and third

redox processes have not been inﬂuenced. The reason,

therefore, is the lower electron-withdrawing eﬀect of the

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The Journal of Organic Chemistry

Article

phosphonate group in methoxy ferrocene 10, leading to a

higher electron density at the ferrocenyl moiety, and as a result

thereof, this compound can more easily be oxidized.

In situ UV−vis/NIR spectroelectrochemical measurements

were additionally carried out for compounds 3 and 10.

However, no intervalence charge transfer absorptions were

found (Supporting Information, Figure S4). This shows that no

direct electronic communication between the Fc and Fc⁺units

occurs, indicating signiﬁcant electrostatic interaction among the

terminal Fc/Fc⁺groups as oxidation progresses.^2,10

Replacing the electron-rich [3]ferrocenophane group in 27a

with a chelating (R)-BINOL substituent in 27b increased the

ﬁrst redox potential from E₁°′ = 110 mV to E₁°′ = 142 mV. A

series of ferrocenophanes inter alia 27b were electrochemically

investigated by Herberhold using [ⁿBu₄N][ClO₄] as electro-

lyte.³⁸There, a lower redox separation of ΔE°′ = 300 mV (E₁°′

= 550 mV, E₂°′ = 850 mV vs SCE) was observed, which is

attributed to the stronger coordinating character of the

electrolyte (vide supra). Zanello et al. studied the redox

behavior of tri- and ditellura-ferrocenophanes and described an

unambiguous assignment of the molecule orbitals in the redox

process.⁶⁷

The apFr of 27b leading to 28b shows a similar redox

behavior (Supporting Information, Figure S3). The electron-

donating eﬀect of the methoxy group to the ferrocenyl moiety

in 28b is superimposed by the electron-withdrawing eﬀect of

the phosphonate moiety.

The methyl groups in the 2,2′-position in 31 shift the redox

potential, in comparison to 30, to lower values (E₁°′ = 254 mV

for 31, E₁°′ = 302 mV for 30) due to their electron-donating

eﬀect. Compound 33, bearing ﬁve ferrocenyls, showed three

redox processes. The four OFc groups are represented by the

ﬁrst two redox events at E₁°′ = 90 mV and E₂°′ = 270 mV. Both

consist of two nonseparated one-electron processes of one

ferrocenyl at each phosphate fragment. The one-electron redox

wave at E₃°′ = 800 mV represents the 1,1′-substituted

ferrocenyl (Table 1). The diﬀerence between the anodic and

cathodic potential of ΔE_p= 135 mV indicates an electro-

chemical irreversibility of the third redox event. The redox

potential at E₃°′ = 800 mV leads to the conclusion that both

phosphate groups, each bearing two oxidized ferrocenyl, exerts

a high electron-withdrawing eﬀect. It is known, for example, for

formyl-substituted ferrocenes that a second substitution of a

monofunctionalized ferrocene with the same functionality leads

to a summation of the electronic eﬀects and, therefore, to a

linear increase or decrease of the redox potential.⁶⁸Molecule

34 containing two [3]ferrocenophane motifs, compared to two

ferrocenyls at the phosphorus atom (33), showed two redox

processes: a one-electron event for the non-bridged and a redox

process with a shoulder including two one-electron processes

for both [3]ferrocenophanes (Figure 7).

Electrochemical measurements of ferrocenyl phosphorami-

dates 46−48 and 51 display two reversible one-electron redox

processes (Table 1). The nature of the N-heterocycle in 46−48

has negligible inﬂuence on the redox potential (Table 1), and as

consequence thereof, the redox separation is ΔE°′ = 160 mV,

identical for all three compounds. A further redox process for

the N-heterocycle was not observed under the applied

measurement conditions. The ﬁrst redox process for 51 is

found at E₁°′ = 40 mV (for comparison, for 48, E₁°′ = 90 mV),

which is attributed to the electron-donating methoxy

substituent (Table 1). The second redox event is E₂°′ = 290

mV for 51, 40 mV higher than in 48, which can be explained by

the more electron-withdrawing inﬂuence of the directly to

phosphorus-bonded Fc⁺moiety.

Besides the importance of the electron density at the

ferrocenyls for limiting a lithiation process, also the nature of

the substituent is relevant. Thus, triferrocenyl phosphate 3 (30

mV, Table 1) underwent an apFr, whereas the borane adduct

40 (62 mV) showed no attack at the phosphorus atom,

although it contained a ferrocenyl unit with a decreased

electron density. Obviously, the strongly electron-donating

cyclic N-alkyl group shields the phosphorus atom and thus

prevents a nucleophilic attack. Compared to N-aryl phosphates

46−48, this is due to the electron-rich N-alkyl substituents,

enabling a better orbital overlap between the N and the P

atoms.

In contrast to the compounds described above, phosphor-

amidates 37−41 did not undergo an apFr, although lithiation

reactions were observed by using the stronger base s-BuLi

instead of LDA (Scheme 12). This indicates that a higher

electron density is present at the ferrocenyls in 37−41, which is

veriﬁed by the lower redox potentials of up to 62 mV for the

borane adduct 40. In contrast, the aromatic derivatives and the

[3]ferrocenophanes 30 and 31 are observed at higher values of

90 mV (Table 1). The low values for phosphonate 9 (−20 mV)

and phosphinate 10 (−60 mV) are misleading, as the ﬁrst redox

event refers to the methoxy-substituted ferrocenyl, which is not

able to undergo an apFr. Within the series of aliphatic

ferrocenyl phosphates, the replacement of a PO (39, −63

mV) by a PS (38, −50 mV) and furthermore a P→BH₃(37,

−29 mV) group decreases the electron density at the

ferrocenyl, while increasing the redox potential. This is contrary

to the results obtained by apFr within the series of

P(E)(OFc)(OEt)₂,⁵with decreasing yields for E = O (94%)

> E = BH₃(37%) > E = S (0%). The latter one could only be

converted by using s-BuLi (50%). Replacement of an N-alkyl

(39) by an FcO moiety (41) shifts the potential for the ﬁrst

redox event from −63 to −14 mV.

CONCLUSIONS

■

A series of O-ferrocenyl-O′-aryl phosphates have been

synthesized and investigated within anionic phospho-Fries

rearrangements (apFr). This 1,3-O→C migration is limited to

one ferrocenyl group within one reaction step, enabling the

phosphonate and phosphinate of triferrocenyl phosphate

P(O)(OFc)₃(Fc = Fe(η⁵-C₅H₅)(η⁵-C₅H₄)) to be easily

accessible. In contrast, the number of phenyl-based rearrange-

ments solely depends on the temperature, requiring a strict

temperature regime within one reaction step. We could show

for the ﬁrst time that in the presence of diﬀerent types of

aromatics, combined within one molecule, the ﬁrst lithiation

and migration process, moreover, take place at the phenyl units,

due to the higher electron density at the ferrocene backbone

and thus their lower basicity. Scavenging of the reactions with

Me₂SO₄also showed a complete methylation of ferrocenyls,

whereas phenyls rather remain with a hydroxy functionality.

The presence of a 1,3-dioxa-[3]ferrocenophane moiety limits

the rearrangements to the non-bridging substituent. In case of a

chiral (R)-BINOL derivative, this proceeds with a >91% de,

resulting in an (R_p) conﬁguration at the ferrocenyl backbone, as

evidenced by single-crystal X-ray diﬀraction analysis. If

rearrangements were excluded, ortho-lithiations took place,

resulting in the presence of an electrophile ortho to the oxygens.

Ferrocenylic P^Vand P^IIIderivatives bearing N- instead of O-

bonded aliphatics do not undergo an apFr, whereas they are

L

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The Journal of Organic Chemistry

Article

1

solvent as the reference signal (chloroform-d₁: H at 7.26 ppm and

lithiated in ortho-position. This could be proven by electro-

chemical investigations, revealing a lower value for the ﬁrst

redox potential and, thus, a higher electron density at the

ferrocenyls and the phosphorus atoms. Replacing N-aliphatic

with N-aromatic 1H-pyrrole, 1H-indole, and 9H-carbazole

moieties allowed 1,3-O→C rearrangements and coincidently

increased the value for the ﬁrst redox event. However, besides

the electron density at the ferrocenyls, clariﬁed by the ﬁrst

redox potential, the shielding of the phosphorus atom toward a

nucleophilic attack is also important. Therefore, triferrocenyl

phosphate 3 (E₁°′ = 30 mV) as a unique example undergoes an

apFr, whereas the borane adduct 40, possessing a higher

potential of E₁°′ = 62 mV, could not be lithiated under identical

reaction conditions. The absence of a lithiation reaction at N-

alkyl-substituted phosphoramidates is due to the higher

electron density of the lone pair of the electrons at the

nitrogen atom, compared to aromatic derivatives. Changing the

base from LDA to s-BuLi resulted in an ortho-lithiation, whereas

an 1,3-O→C rearrangement did not occur, due to the shielding

of the phosphorus atom.

¹³C{¹H} at 77.00 ppm; benzene-d₆: H at 7.16 ppm and ¹³C{¹H} at

1

128.06 ppm; dimethylsulfoxide-d₆: H at 2.50 ppm and ¹³C{¹H} at

1

39.52 ppm), by external standards (³¹P{¹H} relative to 85% H₃PO₄,

0.0 ppm and P(OMe)₃, 139.0 ppm), or by the ²H solvent lock signal.⁷⁷

For compounds consisting of mixtures of diﬀerent diastereomers, the

main diastereomer was assigned to be the major (ma) and the

remaining diastereomer to be the minor (mi) stereoisomer.

The melting or decomposition points were determined by using a

Gallenkamp MFB 595 010 M melting point apparatus. Elemental

analyses were performed with a Thermo FlashAE 1112 instrument.

High-resolution mass spectra were recorded with a Bruker Daltonik

micrOTOF-QII spectrometer.

Electrochemistry. Electrochemical measurements on 3−7, 9, 10,

27a,b, 28a,b, 30, 31, 33, 34, 37−41, 46−48, and 51 (1.0 mmol·L⁻¹)

using 0.1 mol·L⁻¹[NBu₄][B(C₆F₅)₄] as the supporting electrolyte⁷⁸in

anhydrous, oxygen-free dichloromethane were performed in a argon-

purged cell at 25 °C with a Radiometer Voltalab PGZ 100

electrochemical workstation interfaced with a personal computer.^70,79

Spectroelectrochemical measurements (Figure S4) were performed in

an optically transparent thin-layer electrochemical cell placed in a

Varian Cary 5000 UV/vis−NIR absorption spectrometer using

anhydrous dichloromethane solutions containing 2.0 mmol L⁻¹of

the analyte and 0.1 mol L⁻¹of [NⁿBu₄][B(C₆F₅)₄] as supporting

electrolyte at 25 °C.⁸⁰Between the spectroscopic measurements, the

applied potentials have been increased stepwise using step heights of

25, 50, or 100 mV. At the end of the measurements, the analyte was

reduced at −400 mV for 30 min and an additional spectrum was

recorded to prove the reversibility of the oxidations.

Besides apFr, the 1,2-N→C migrations also occurred for the

pyrrole and indole derivatives. The identity and absolute

conﬁguration of some compounds could inter alia be veriﬁed by

using single-crystal X-ray diﬀraction analysis. The measure-

ments conﬁrmed the formation of intra- or intermolecular

hydrogen bridge bonds for compounds possessing OH and NH

functionalities.

For the voltammetric measurements, a three-electrode cell

containing a Pt auxiliary electrode, a glassy carbon working electrode

(surface area 0.031 cm²), and a Ag/Ag⁺(0.01 mmol L⁻¹[AgNO₃])

reference electrode ﬁxed on a Luggin capillary was used. The working

electrode was pretreated by being polished on a Buehler microcloth

ﬁrst with 1 μm and then with a 1/4 μm diamond paste. The reference

electrode was constructed from a silver wire inserted into a 0.01 mmol

L⁻¹solution of [AgNO₃] and 0.1 mol L⁻¹of an [NBu₄][B(C₆F₅)₄]

acetonitrile solution in a Luggin capillary with a CoralPor tip. This

Luggin capillary was inserted in a second Luggin capillary containing a

0.1 mol L⁻¹[NBu₄][B(C₆F₅)₄] dichloromethane solution and a

CoralPor tip. Experiments under the same conditions showed that all

reduction and oxidation potentials were reproducible within 5 mV.

Experimental potentials were referenced against a Ag/Ag⁺reference

electrode, but the presented results are referenced against ferrocene as

an internal standard as required by IUPAC.⁸¹To achieve this, each

experiment was repeated in the presence of 1 mmol L⁻¹of

decamethylferrocene (Fc*). Data were processed on a Microsoft

Excel worksheet to set the formal reduction potentials of the FcH/

FcH⁺couple to 0.0 V.⁸²Under our conditions, the Fc*/Fc*⁺couple

was at −614 mV vs FcH/FcH⁺, ΔE_p= 60 mV, while the FcH/FcH⁺

couple was at 220 mV vs Ag/Ag⁺, ΔE_p= 61 mV.

Single-Crystal X-ray Diﬀraction Analysis. Data of 4, 6, 9, 10,

13, 16a, 22b, 24, 26b, 27a, 28b, 31, 34, 40, 47, 48, 51, 52, and 53

were collected with an Oxford Gemini S diﬀractometer at ≤120 K with

graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). The

molecular structures were solved by direct methods using SHELXS-

13⁸³and reﬁned by full-matrix least-squares procedures on F²using

SHELXL-13.^58,84All non-hydrogen atoms were reﬁned anisotropically,

and a riding model was employed in the treatment of the hydrogen

atom positions, unless otherwise noted. Graphics of the molecular

structures were created using ORTEP.⁸⁵

EXPERIMENTAL SECTION

■

General. All reactions were carried out under an atmosphere of

argon using standard Schlenk techniques. For column chroma-

tography, either silica with a particle size of 40−60 μm (230−400

mesh (ASTM)) or alumina with a particle size of 90 μm was used. The

assignment and labeling of the H and C atoms in the NMR follows the

IUPAC recommendations.⁶⁹

Reagents. Tetrahydrofuran and hexane were puriﬁed by distillation

from sodium/benzophenone ketyl, diethyl ether by distillation from

sodium, and N,N-diisopropyl amine by distillation from calcium

hydride. POCl₃(2a) was distilled prior to usage.

Ferrocene, ClSn(ⁿBu)₃, iodine, 1H-pyrrole, 1H-indole, 9H-carba-

t

zole, [BH₃·THF] (1 M), BuOOH (5.5 M in decane), 1-naphthol, 2

naphthol, 3-hydroxypyridine, 2-(methylamino)ethanol, butyllithium

(2.5 M solution in hexane), s-BuLi (1.3 M in cyclohexane), LiTMP,

dimethyl sulfate, triphenylphosphate, pyrrolidine, sulfur, (R)-[1,1′-

binaphthalene]-2,2′-diol, (1R)-α-fenchol, dichlorophenyl phosphate

(2b), and chlorodiphenyl phosphate (2c) were purchased from

commercial suppliers and were used without further puriﬁcation.

Ferrocenol (1),^5,411,1′-ferrocenediol (29),^5,41dichloro(1R)-α-

fenchyl phosphate (2h),¹¹1-chloro-N,N,N′,N′-tetraethylphosphinedi-

amine (2i),⁷⁰chlorodi(pyrrolidin-1-yl)phosphinate (2j),⁷¹dichloro-

N,N-diethylphosphinamine (2l),⁷²2-chloro-3-methyl-1,3,2-oxazaphos-

pholidine (2k),⁷³and [NBu₄][B(C₆F₅)₄]⁷¹were synthesized according

to literature procedures reported elsewhere.

The chlorophosphates 2d,e,g,n,j have already been described,

however, by using BuLi as the base instead of an amine. The

spectroscopic data are in agreement with those reported in literature:

dichloro-1-naphthylphosphate (2d),⁷⁴dichloro-2-naphthylphosphate

(2e),⁷⁵(11bR)-4-chlorodinaphtho[2,1-d:1′,2′-f ][1,3,2]dioxaphos-

phepine 4-oxide (2g),⁷⁶and dichloro(1H-indol-1-yl) phosphonate

(2n).^52aThe synthesis and behavior toward anionic phospho-Fries

rearrangements of 3, 4, and 5 as well as the spectroscopic data of all

their rearrangement products have been described.²

Synthesis of Ferrocenyl Phosphates and Phosphonates:

General Procedure. In a Schlenk tube, the respective amount of

ferrocenol (1) or 1,1′-ferrocenediol (29) was dissolved in 20 mL of

tetrahydrofuran, and the obtained solution was cooled to −30 °C.

BuLi (1, 1 equiv; 29, 2 equiv) was added dropwise, and the suspension

was stirred for 10 min at this temperature. The mixture was cooled to

−70 °C, and 1 equiv of the respective chlorophosphates 2g,i−k or 0.5

equiv of the respective dichlorophosphates 2d−f,h,l−o was added with

a Pasteur pipet in a single portion. After allowing the reaction mixture

Instruments. NMR spectra were recorded with a Bruker Avance

III 500 spectrometer (500.3 MHz for H, 160.4 MHz for ¹¹B, 125.8

1

MHz for ¹³C, and 202.5 MHz for ³¹P) and are reported with chemical

shifts in δ (ppm) units downﬁeld from tetramethylsilane with the

M

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The Journal of Organic Chemistry

Article

to warm to ambient temperature, we continued stirring for 18 h, and

all volatiles were removed in vacuum. The crude products were ﬁltered

through 5 cm of alumina using a 1:1 dichloromethane/ethyl acetate

(v/v) mixture as the eluent to remove unreacted 1. Puriﬁcation was

realized by column chromatography (silica or alumina; for column

size, see below) using diﬀerent solvent mixtures (see below). After

removal of all volatiles in vacuum, the respective phosphates were

obtained as orange solids or oils.

120.6 (d, J_C,P= 2.9 Hz, CH), 121.2 (d, J_C,P= 2.1 Hz, ^qC), 121.5 (d, J_C,P

= 2.3 Hz, ^qC), 125.89 (CH), 125.92 (CH), 126.9 (CH), 127.0 (CH),

127.2 (CH), 128.45 (CH), 128.54 (CH), 131.1 (CH), 131.6 (CH),

131.7 (d, J_C,P= 0.9 Hz, ^qC), 132.0 (d, J_C,P= 1.1 Hz, ^qC), 132.26 (d, J_C,P

= 0.8 Hz, C), 132.27 (d, J_C,P= 1.0 Hz, C), 146.1 (d, J_C,P= 8.2 Hz,

C2/2′), 147.4 (d, ²J_C,P= 11.4 Hz, C2/2′). ³¹P{¹H} NMR (CDCl₃, δ):

−2.5. HRMS (ESI-TOF) m/z: [M + Na]⁺calcd for C₃₀H₂₁FeO₄P +

Na 555.0419; found 555.0401.

q

2

Diferrocenyl(1-naphthyl) Phosphate (6). Ferrocenol (1, 600 mg,

2.97 mmol), BuLi (1.2 mL, 3.0 mmol), and dichloro(1-naphthyl)

phosphate (2d, 388 mg, 1.5 mmol) were reacted according to the

general procedure described above. Puriﬁcation was realized by

column chromatography (silica, column size 2.5 × 15 cm) using a 9:1

dichloromethane/hexane mixture (v/v) as the eluent. The title

compound 6 was obtained as an orange solid. Crystals, suitable for

single-crystal X-ray diﬀraction analysis, were obtained by crystallization

from a boiling hexane solution containing 6. Yield: 195 mg (0.364

mmol, 25% based on 1). Anal. Calcd for C₃₀H₂₅Fe₂O₄P·1/6C₆H₁₄

(592.18·1/6 86.18 g/mol): C, 61.39; H, 4.54. Found: C, 61.39; H,

1,3-Dioxa-2-((1R)-α-fenchyl)(oxo)phospha-[3]ferrocenophane

(30). Ferrocene-1,1′-diol (29, 600 mg, 2.75 mmol), BuLi (2.20 mL,

5.50 mmol), and dichloro-(1R)-α-fenchyl phosphate (2h, 749 mg,

2.752 mmol) were reacted according to the general procedure

described above. Puriﬁcation was realized by column chromatography

(silica, column size 2.5 × 12 cm) using a 95:5 dichloromethane/ethyl

acetate (v/v) mixture as the eluent. The title compound was obtained

as an orange solid. Yield: 214 mg (0.51 mmol, 19% based on 29). Anal.

Calcd for C₂₀H₂₅FeO₄P (416.23 g/mol): C, 57.71; H, 6.05. Found: C,

58.04; H, 6.35. Mp: 130−133 °C. ¹H NMR (CDCl₃, δ): 1.01 (s, 3 H,

CH₃), 1.12 (s, 3 H, CH₃), 1.13−1.17 (m, 1 H, H5/6), 1.20 (s, 3 H,

CH₃), 1.22−1.24 (m, 1 H, H7), 1.46−1.52 (m, 1 H, H5/6), 1.56 (ddd,

J_H,H= 10.5 Hz, J_H,H= 3.8 Hz, J_H,H= 2.2 Hz, 1 H, H7), 1.74−1.85 (m, 3

H, H5/6, H4), 4.01 (ddd, J_H,P= 3.9 Hz, J_H,H= 2.6 Hz, J_H,H= 1.3 Hz, 2

1

3,4

4.63. Mp: 130−134 °C. H NMR (CDCl₃, δ): 3.91 (pt,

J

= 1.9

H,H

Hz, 4 H, H3,4_C5H4), 4.21 (s, 10 H, C₅H₅), 4.44−4.46 (m, 4 H,

H2,5_C5H4), 7.45 (t, J_H,H= 7.9 Hz, 1 H, H3_C10H7), 7.53−7.56 (m, 3 H,

H2/6/7_C10H7), 7.72 (d, J_H,H= 8.1 Hz, 1 H, H4_C10H7), 7.86−7.88 (m, 1

H, H5_C10H7), 8.11−8.13 (m, 1 H, H8_C10H7). ¹³C{¹H} NMR (CDCl₃,

3

H, C₅H₄), 4.05−4.06 (m, 2 H, C₅H₄), 4.20 (dd, J_H,P= 8.2 Hz, 1 H,

H2), 4.38 (dtd, J_H,P= 4.4 Hz, J_H,H= 2.6 Hz, J_H,H= 1.3 Hz, 2 H, C₅H₄),

4.63−4.64 (m, 2 H, C₅H₄). ¹³C{¹H} NMR (CDCl₃, δ): 19.1 (CH₃),

3

δ): 59.86 (d, J_C,P= 3.9 Hz, C2/5_C5H4), 59.90 (d, J_C,₃_P= 3.7 Hz, C2/

5_C5H4), 62.9 (C3/4_C5H4), 69.6 (C₅H₅), 115.1 (d, J_C,P= 2.9 Hz,

C2_C10H7), 117.9 (d, ²J_C,P= 5.3 Hz, C_C5H4−O), 121.7 (C8_C10H7), 125.39

20.8 (CH₃), 25.83 (C5/6), 25.87 (C5/6), 29.8 (CH₃), 39.7 (d, ³J_C,P

=

2.6 Hz, C3), 40.9 (C7), 47.9 (C4), 49.3 (d, ³J_C,P= 5.5 Hz, C1), 63.30

3

(C₅H₄), 63.32 (C₅H₄), 63.35 (C₅H₄), 63.36 (C₅H₄), 66.0 (C₅H₄),

(C3_C10H7), 125.40 (C4_C10H7), 126.3 (d, J_C,P= 6.9 Hz, C8a_C10H7),

2

66.92 (C₅H₄), 66.93 (C₅H₄), 93.9 (d, J_C,P= 7.7 Hz, C2), 109.4 (d,

126.5 (C6/7_C10H7), 126.8 (C6/7_C10H7), 127.7 (C5_C10H7), 134.8

2

(C4a_C10H7), 146.4 (d, J_C,P= 7.6 Hz, C1_C10H7). ³¹P{¹H} NMR

²J_C,P= 10.3 Hz, C_C5H4−O), 109.5 (d, J_C,P= 10.4 Hz, C_C5H4−O).

(CDCl₃, δ): −15.6. HRMS (ESI-TOF) m/z: [M]⁺calcd for

C₃₀H₂₅Fe₂O₄P 592.0185; found 592.0160.

³¹P{¹H} NMR (CDCl₃, δ): 0.3. HRMS (ESI-TOF) m/z: [M₂+ Na]⁺

calcd for (C₂₀H₂₅FeO₄P)₂+ Na 855.1574; found 855.1581.

Diferrocenyl(2-naphthyl) Phosphate (7). Ferrocenol (1, 836 mg,

4.138 mmol), BuLi (1.7 mL, 4.25 mmol), NEt₃(0.6 mL, 4.3 mmol),

and dichloro(2-naphthyl) phosphate (2e, 515 mg, 1.973 mmol) were

reacted according to the general procedure described above.

Puriﬁcation was realized by column chromatography (silica, column

size 2.5 × 35 cm) using chloroform as the eluent. The title compound

was obtained as an orange oil. Yield: 380 mg (0.64 mmol, 65% based

on 2e). Anal. Calcd for C₃₀H₂₅Fe₂O₈P₂·1/3 C₆H₁₄(741.99·1/3 86.18

g/mol): C, 49.87; H, 3.75. Found: C, 49.65; H, 3.59. Mp: >230 °C

Synthesis of 27a and 33. 1,1′-Ferrocenediol (29, 150 mg, 0.688

mmol) was dissolved in 30 mL of diethyl ether, and the solution was

cooled to −30 °C. BuLi (0.55 mL, 1.375 mmol) was dropwise added,

and stirring was continued for 10 min at this temperature. Afterward,

the mixture was cooled to −70 °C and POCl₃(2a, 0.125 mL, 1.376

mmol) was added in a single portion. Separately, ferrocenol (1, 603

mg, 2.98 mmol) was dissolved in 30 mL of diethyl ether and cooled to

−30 °C, and BuLi (1.2 mL, 3 mmol) was dropwise added. Both

reaction mixtures were tempered at −30 °C, and the mixture

containing 1 was slowly added to the one containing 29 by using a

transfer cannula. The cooling bath was removed, and stirring was

continued for 18 h, followed by the removal of all volatiles in vacuum.

Puriﬁcation was realized by column chromatography (silica, 2 × 15

cm), resulting three fractions. Fraction 1 (dichloromethane, R_f= 0.52)

contained P(O)(OFc)₃(3, 330 mg, 0.415 mmol, 42% based on 1);

fraction 2 contained compound 27a (95:5 dichloromethane/ethyl

acetate (v/v) mixture, R_f= 0.57), and fraction 3 contained 33 (95:5

dichloromethane/ethyl acetate (v/v) mixture, R_f= 0.41).

1

3,4

(decomp.). H NMR (CDCl₃, δ): 3.93 (pt,

J

= 2.0 Hz, 4 H,

H,H

H3,4_C5H4), 4.26 (s, 10 H, C₅H₅), 4.46−4.48 (m, 4 H, H2,5_C5H4), 7.39

3

4

(dd, J_H,H= 8.9 Hz, J_H,H= 2.4 Hz, 1 H, H3), 7.45−7.53 (m, 2 H,

C₁₀H₇), 7.73−7.75 (m, 1 H, H1), 7.82−7.87 (m, 3 H, C₁₀H₇).

¹³C{¹H} NMR (CDCl₃, δ): 59.76 (d, ³J_C,P= 4.1 Hz, C2/5_C5H4), 59.77

(d, ³J_C,P= 4.0 Hz, C2/5_C5H4), 62.9 (s, C₅H₄), 69.7 (s, C₅H₅), 116.5 (d,

³J_C,P= 5.0 Hz, C1), 117.9 (d, ²J_C,P= 5.4 Hz, C_C5H4−O), 119.8 (d, ³J_C,P

= 5.0 Hz, C3), 125.7 (C₁₀H₇), 126.9 (C₁₀H₇), 127.6 (C₁₀H₇), 127.7

2

(C₁₀H₇), 130.0 (C4), 131.1 (C8a), 133.8 (C4a), 148.0 (d, J_C,P= 7.4

Hz, C2). ³¹P{¹H} NMR (CDCl₃, δ): −16.0. HRMS (ESI-TOF) m/z:

1,3-Dioxa-2-(ferrocenyloxy)(oxo)phospha-[3]ferrocenophane

(27a). The spectroscopic data of this compound are in agreement with

those reported in ref 38. Crystals, suitable for single-crystal X-ray

diﬀraction analysis, were obtained by crystallization from a boiling

hexane solution containing 27a. Yield: 63 mg (0.136 mmol, 20% based

[M]⁺calcd for C₃₀H₂₅Fe₂O₄P 592.0185; found 592.0160.

(R)-1,1′-Binaphthyl-2,2′-diylferrocenyl phosphate (27b). Ferroce-

nol (1, 235 mg, 1.16 mmol), BuLi (0.47 mL, 1.18 mmol), and (R)-

1,1′-binaphthyl-2,2′-diyl chlorophosphate (2g, 427 mg, 1.16 mmol)

were reacted according to the general procedure described above.

Puriﬁcation was realized by column chromatography (silica, column

size 2.5 × 8 cm) using a 99:1 dichloromethane/ethyl acetate mixture

(v/v) as the eluent (R_f= 0.26). The title compound was obtained as an

orange solid. Yield: 305 mg (0.57 mmol, 49% based on 1). Anal. Calcd

for C₃₀H₂₁FeO₄P·1/3 C₆H₁₄(532.31·1/3 86.18 g/mol): C, 68.51; H,

1

3,4

on 29). H NMR (CDCl₃, δ): 3.96 (pt,

J

= 1.9 Hz, 2 Hz, C₅H₄,

H,H

3,4

FcO), 4.07 (pt,

J

= 2.0 Hz, 4 Hz, C₅H₄, ansa), 4.33 (s, 5 H,

H,H

3,4

C₅H₅), 4.41−4.42 (m, 2 H, C₅H₄, ansa), 4.50 (pt,

J

= 1.8 Hz, 2

H,H

Hz, C₅H₄, FcO), 4.58−4.59 (m, 2 H, C₅H₄, ansa). ¹³C{¹H} NMR

(CDCl₃, δ): 59.4 (d, J_C,P= 4.4 Hz, C₅H₄, FcO), 62.8 (d, J_C,P= 3.1 Hz,

C₅H₄, ansa), 63.0 (s, C₅H₄, FcO), 63.7 (d, J_C,P= 3.4 Hz, C₅H₄, ansa),

2

1

66.8 (s, C₅H₄, ansa), 69.8 (C₅H₅), 109.9 (d, J_C,P= 12.5 Hz, C−O,

4.61. Found: C, 68.56; H, 4.48. Mp: 247 °C. H NMR (CDCl₃, δ):

ansa), 118.0 (d, J_C,P= 6.1 Hz, C−O, FcO). ³¹P{¹H} NMR (CDCl₃,

2

3.89−3.91 (m, 1 H, H3/4-C₅H₄), 3.93−3.94 (m, 1 H, H3/4-C₅H₄),

4.31 (s, 5 H, C₅H₅), 4.34−4.40 (m, 1 H, H2/5-C₅H₄), 4.54−4.56 (m,

1 H, H2/5-C₅H₄), 7.30−7.41 (m, 4 H, C₁₀H₈), 7.14−7.52 (m, 3 H,

C₁₀H₈), 7.65 (d, J_H,H= 8.8 Hz, 1 H, C₁₀H₈), 7.96−7.98 (m, 2 H,

C₁₀H₈), 8.03 (d, J_H,H= 8.9 Hz, 1 H, C₁₀H₈), 8.07 (d, J_H,H= 8.9 Hz, 1

H, C₁₀H₈). ¹³C{¹H} NMR (CDCl₃, δ): 59.8 (d, J_C,P= 4.6 Hz, C₅H₄),

59.9 (d, J_C₂_,P= 3.5 Hz, C₅H₄), 62.9 (C₅H₄), 63.0 (C₅H₄), 69.8 (C₅H₅),

117.9 (d, J_C,P= 5.0 Hz, C_C5H4−O), 120.2 (d, J_C,P= 3.3 Hz, CH),

δ): −5.6. HRMS (ESI-TOF) m/z: [M + H]⁺calcd for C₂₀H₁₇Fe₂O₄P

+ H 464.9636; found 464.9608.

(1,1′-Ferrocenediyl)tetraferrocenyl Bis(phosphate) (33). Yield: 86

1

mg (0.077 mmol, 11% based on 29). Mp: 167 °C. H NMR (CDCl₃,

3,4

δ): 3.93 (pt,

J

= 2.0 Hz, 8 H, FcO), 4.05 (pt, ^3,4J_H,H= 2.0 Hz, 4 H,

H,H

FcO₂), 4.28 (s, 20 H, C₅H₅), 4.44 (dd, J_H,P= 4.4 Hz, J_H,H= 2.1 Hz, 8

3,4

H, FcO), 4.52 (pt,

J

= 2.0 Hz, 4 H, FcO₂). ¹³C{¹H} NMR

H,H

N

DOI: 10.1021/acs.joc.7b00030

J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

Article

3

(CDCl₃, δ): 59.65 (C₅H₄, FcO), 59.66 (C₅H₄, FcO), 59.69, (C₅H₄,

FcO), 59.70 (C₅H₄, FcO), 61.16 (C₅H₄, FcO₂), 61.20 (C₅H₄, FcO₂),

62.93 (C₅H₄, FcO), 62.94 (C₅H₄, FcO), 65.1 (C₅H₄, FcO₂), 69.7

(C₅H₅), 117.8 (d, ²J_C,P= 5.5 Hz, C−O, FcO), 118.1 (d, ²J_C,P= 5.4 Hz,

C−O, FcO₂). ³¹P{¹H} NMR (CDCl₃, δ): −15.3. HRMS (ESI-TOF)

m/z: [M]⁺calcd for C₅₀H₄₄Fe₅O₈P₂1113.9260; found 1113.9205.

1,1′-Bis(1,3-dioxa-2-(oxo)phospha-[3]ferrocenophan-2-yloxy)-

ferrocene (34). 1,1′-Ferrocenediol (29, 642 mg, 2.94 mmol) was split

in three portions of 214 mg (0.982 mmol), and each of them was

dissolved in 10 mL of diethyl ether. The solutions were cooled to −30

°C, and BuLi (0.79 mL, 1.96 mmol) was dropwise added. The ﬁrst

portion was cooled to −70 °C, POCl₃(2a, 0.18 mL, 1.96 mmol) was

added quickly via syringe, and the reaction mixture was slowly warmed

to ambient temperature. After being stirred for 10 min at this

temperature, the reaction mixture was cooled again to −70 °C and the

second portion of lithiated 1,1′-Fc(OH)₂(29-Li₂) was added via a

transfer cannula. The same procedure was repeated for the third

fraction of 29-Li₂. Afterward, the mixture was allowed to warm to

ambient temperature and stirred for 18 h. All volatiles were removed in

vacuum. Puriﬁcation was realized using column chromatography

(silica, column size 2 × 12 cm) using a 95:5 dichloromethane/ethyl

acetate mixture (v/v) as the eluent. Compound 34 was obtained as an

orange solid. The spectroscopic data are in agreement with those

reported in ref 38. Crystals, suitable for single-crystal X-ray diﬀraction

analysis, were obtained by crystallization from a boiling hexane

solution containing 34. Yield: 94 mg (0.127 mmol, 12% based on 29).

Anal. Calcd for C₃₀H₂₄Fe₂O₈P₂·1/3 C₆H₁₄(741.99·1/3 86.18 g/mol):

C, 49.87; H, 3.75. Found: C, 49.65; H, 3.59. Mp: >230 °C (decomp.).

¹H NMR (CDCl₃, δ): 4.06−4.07 (m, 8 H, ansa), 4.17 (pt, ^3,4J_H,H= 2.0

(t, J_H,H= 7.1 Hz, 12 H, CH₃), 3.00−3.09 (m, 8 H, CH₂), 3.70 (pt,

3,4 3,4

J

= 2.0 Hz, 2 H, C₅H₄), 4.22 (s, 5 H, C₅H₅), 4.50 (ptd,

J

=

H,H

2.1 Hz, J_H,H= 0.6 Hz, 2 H, C₅H₄). ¹³C{¹H} NMR (C₆D₆, δ): 14.2 (d,

⁴J_C,P= 3.2 Hz, CH₃), 40.6 (d, ³J_C,P= 5.0 Hz, CH₂), 61.4 (d, J_C,P= 3.6

2

Hz, C₅H₄), 62.9 (C₅H₄), 69.8 (C₅H₅), 117.6 (d, J_C,P= 1.9 Hz,

C_C5H4−O). ³¹P{¹H} NMR (C₆D₆, δ): 90.9. HRMS (ESI-TOF) m/z:

[M]⁺calcd for C₁₈H₂₉FeN₂OPS 408.1082; found 408.1109.

Ferrocenyl Di(pyrrolidin-1-yl)phosphinate (39). Ferrocenol (1,

370 mg, 1.83 mmol), BuLi (0.73 mL, 1.83 mmol), and chlorodi-

(pyrrolidin-1-yl) phosphinate (2j, 408 mg, 1.83 mmol) were reacted at

−80 °C according to the general procedure described above.

Puriﬁcation was realized by column chromatography (alumina, column

size 4 × 8 cm) using a 1:1 dichloromethane/ethyl acetate mixture (v/

v) as the eluent. The title compound was obtained as an orange solid.

Yield: 512 mg (1.319 mmol, 72% based on 1). Anal. Calcd for

C₁₈H₂₅FeN₂O₂P (388.22 g/mol): C, 55.69; H, 6.49; N, 7.27. Found:

C, 55.67; H, 6.54; N, 7.09. Mp: 76−78 °C. ¹H NMR (C₆D₆, δ): 1.40−

1.43 (m, 8 H, H3,H4−C₄N), 3.11−3.15 (m, 8 H, H2,H5−C₄N), 3.71

3,4

(pt,

J

= 1.9 Hz, 2 H, C₅H₄), 4.27 (s, 5 H, C₅H₅), 4.60 (ptd, ^3,4J_H,H

H,H

= 1.9 Hz, J_H,P= 0.6 Hz, 2 H, C₅H₄). ¹³C{¹H} NMR (C₆D₆, δ): 26.5 (d,

³J_C,P= 8.9 Hz, C3,C4−C₄N), 46.8 (d, J_C,P= 4.6 Hz, C2,C5−C₄N),

2

60.3 (d, J_C,P= 3.8 Hz, C₅H₄), 62.8 (C₅H₄), 69.9 (C₅H₅), 118.5 (d, ²J_C,P

= 4.3 Hz, C_C5H4−O). ³¹P{¹H} NMR (C₆D₆, δ): 22.8. HRMS (ESI-

TOF) m/z: [M + Na]⁺calcd for C₁₈H₂₅FeN₂O₂P + Na 411.0895;

found 411.0895.

2-Ferrocenyloxy-3-methyl-1,3,2-oxaphospholidine·BH₃(40). Fer-

rocenol (1, 508 mg, 2.51 mmol), triethylamine (0.39 mL, 2.81 mmol),

and 2-chloro-3-methyl-1,3,2-oxazaphospholidine (2k, 350 mg, 2.51

mmol) were reacted according to the general procedure described

above. After stirring for 12 h, a 1 M solution of BH₃in tetrahydrofuran

(2.8 mL, 2.8 mmol) was added in a single portion and stirring was

continued for an additional 2 h. Puriﬁcation was realized by column

chromatography (alumina, column size 3.5 × 13 cm) using a 1:3

hexane/dichloromethane mixture (v/v) as the eluent. The title

compound 40 was obtained as an orange oil. Crystals, suitable for

single-crystal X-ray diﬀraction analysis, were obtained by evaporation

of a hexane solution at ambient temperature containing 40. Yield: 270

mg (0.847 mmol, 34% based on 1). Anal. Calcd for C₁₃H₁₉BFeNO₂P

(318.92 g/mol): C, 48.96; H, 6.00; N, 4.39. Found: C, 49.28; H, 6.08;

Hz, 4 H, open), 4.44−4.45 (m, 4 H, ansa), 4.56−4.57 (m, 4 H, ansa),

4.66 (pt, ^3,4J_H,H= 1.9 Hz, 4 H, open). ¹³C{¹H} NMR (CDCl₃, δ): 61.2

(d, J_C,P= 4.5 Hz, open), 62.9 (d, J_C,P= 3.0 Hz, ansa), 63.7 (d, J_C,P= 3.6

Hz, ansa), 65.2 (open), 66.8 (ansa), 66.9 (ansa), 109.9 (d, ²J_C,P= 12.8

2

Hz, C_C5H4−O, ansa), 118.3 (d, J_C,P= 6.0 Hz, C_C5H4−O, open).

³¹P{¹H} NMR (CDCl₃, δ): −5.6. HRMS (ESI-TOF) m/z: [M + Na]⁺

calcd for C₃₀H₂₄Fe₃O₈P₂+ Na 764.8889; found 764.8862.

N,N,N′,N′-Tetraethyl-1-(ferrocenyloxy)phosphinediamine·BH₃

(37). Ferrocenol (1, 1.037 g, 5.13 mmol), triethylamine (0.75 mL, 5.41

mmol), and ClP(NEt₂)₂(2i, 1.09 mL, 5.17 mmol) were reacted

according to the general procedure described above. After stirring for

12 h, a 1 M solution of BH₃in tetrahydrofuran (5.2 mL, 5.2 mmol)

was added in a single portion and stirring was continued for an

additional 2 h. Puriﬁcation was realized by column chromatography

(alumina, column size 3.5 × 13 cm) using a 8:2 hexane/diethyl ether

mixture (v/v) as the eluent. Compound 37 was obtained as an orange

oil. Yield: 1.02 g (2.61 mmol, 51% based on 1). Anal. Calcd for

C₁₈H₃₂BFeN₂OP (390.09 g/mol): C, 55.42; H, 8.27; N, 7.18. Found:

C, 55.55; H, 8.08; N, 6.92. IR data (NaCl, ν/cm⁻¹): 3067, w, 3020 w,

2942 s, 2905 s, 2852 s, 2353 s (BH₃), 1446 s, 1399 w, 1366 s, 1285 m.

1

N, 4.35. Mp: 153 °C. H NMR (CDCl₃, δ): 0.31−0.86 (br m, 3 H,

BH₃), 2.79 (d, ³J_H,P= 10.1 Hz, 3 H, CH₃), 2.97 (ddd, ³J_H,P= 13.1 Hz,

³J_H,H= 7.5 Hz, J_H,H= 4.8 Hz, 1 H, CH₂−N), 3.08 (dtd, J_H,P= 11.9

Hz, J_H,H= 8.0 Hz, J_H,H= 5.9 Hz, 1 H, CH₂−N), 3.89 (pt, ^3,4J_H,H= 2.0

Hz, 2 H, C₅H₄), 4.14−4.25 (m, 8 H, C₅H₅, C₅H₄, CH₂−O), 4.29−4.30

3

(m, 1 H, C₅H₄). ¹³C{¹H} NMR (CDCl₃, δ): 31.2 (d, J_C,P= 9.9 Hz,

2

CH₃), 49.2 (d, ²J_C,P= 2.2 Hz, CH₂−N), 60.6 (d, J_C,P= 1.4 Hz, C₅H₄),

61.2 (d, J_C,P= 1.8 Hz, C₅H₄), 63.2 (d, J_C,P= 19.1 Hz, C₅H₄), 67.9 (d,

²J_C,P= 10.5 Hz, CH₂−O), 69.6 (C₅H₅), 116.5 (d, J_C,P= 11.2 Hz,

2

C_C5H4−O). ¹¹B{¹H} NMR (CDCl₃, δ): −42.6 (d, J_B,P= 92 Hz).

1

3

¹H NMR (C₆D₆, δ): 0.93 (t, J_H,H= 7.1 Hz, 12 H, CH₃), 1.01−1.72

³¹P{¹H} NMR (CDCl₃, δ): 122.0 (br m). HRMS (ESI-TOF) m/z: [M

+ Na]⁺calcd for C₁₃H₁₉BFeNO₂P + Na 342.0491; found 342.0499.

Diferrocenyl-N,N-diethyphosphoramidate (41). Ferrocenol (1,

414 mg, 2.05 mmol), triethylamine (0.29 mL, 2.05 mmol), and

Cl₂PNEt₂(2l, 178 mg, 1.025 mmol) were reacted according to the

(br m, 3 H, BH₃), 2.86−3.03 (m, 8 H, CH₂), 3.67 (pt, ^3,4J_H,H= 2.0 Hz,

2 H, C₅H₄), 4.19 (s, 5 H, C₅H₅), 4.42 (pt, ^3,4J_H,H= 2.0 Hz, 2 H, C₅H₄).

¹³C{¹H} NMR (C₆D₆, δ): 14.3 (d, ³J_C,P= 1.7 Hz, CH₃), 39.2 (d, ²J_C,P

= 6.3 Hz, CH₂), 61.4 (d, J_C,P= 2.7 Hz, C₅H₄), 63.0 (C₅H₄), 69.7

(C₅H₅), 118.1 (d, ²J_C,P= 1.4 Hz, C_C5H4−O). ¹¹B{¹H} NMR (C₆D₆, δ):

t

1

−39.5 (d, J_B,P= 95 Hz). ³¹P{¹H} NMR (C₆D₆, δ): 130.7−132.1 (br

general procedure described above. After stirring for 12 h, BuOOH

m). HRMS (ESI-TOF) m/z: [M]⁺calcd for C₁₈H₃₂BFeN₂OP

390.1693; found 390.1702.

(0.38 mL, 2.09 mmol) was added and stirring was continued for an

additional 2 h. Puriﬁcation was realized by column chromatography

(alumina, column size 4.5 × 12 cm) using dichloromethane as the

eluent. The title compound 41 was obtained as an orange solid.

Crystals, suitable for single-crystal X-ray diﬀraction analysis, were

obtained by evaporation of a hexane solution at ambient temperature

containing 41. Yield: 253 mg (0.618 mmol, 60% based on 1). Anal.

Calcd for C₂₄H₂₈Fe₂NO₃P (521.15 g/mol): C, 55.31; H, 5.42; N, 2.69.

Found: C, 55.04; H, 5.74; N, 2.64. Mp: 103 °C. ¹H NMR (CDCl₃, δ):

1.03 (t, ³J_H,H= 7.1 Hz, 6 H, CH₃), 3.07 (q, ³J_H,H= 7.1 Hz, 2 H, CH₂),

3.09 (q, ³J_H,H= 7.1 Hz, 2 H, CH₂), 3.87−3.90 (m, 4 H, C₅H₄), 4.27 (s,

10 H, C₅H₅), 4.34−4.35 (m, 2 H, C₅H₄), 4.50−4.51 (m, 2 H, C₅H₄).

¹³C{¹H} NMR (CDCl₃, δ): 13.9 (d, ³J_C,P= 2.0 Hz, CH₃), 39.7 (d, ²J_C,P

= 4.5 Hz, CH₂), 59.6 (d, J_C,P= 4.5 Hz, C₅H₄), 60.2 (d, J_C,P= 3.3 Hz,

N,N,N′,N′-Tetraethyl-1-(ferrocenyloxy)phosphinediamine sulﬁde

(38). Ferrocenol (1, 1.102 g, 5.46 mmol), triethylamine (0.77 mL,

5.55 mmol), and ClP(NEt₂)₂(2i, 1.26 g, 5.98 mmol) were reacted

according to the general procedure described above. After stirring for

12 h, sulfur (210 mg, 6.55 mmol) was added in a single portion and

stirring was continued for an additional 2 h. Puriﬁcation was realized

by column chromatography (alumina, column size 2.5 × 32 cm) using

ﬁrst hexane, to remove the excess of sulfur, followed by a 7:3 hexane/

dichloromethane mixture (v/v) as the eluent. Compound 38 was

obtained as an orange oil. Yield: 1.900 g (4.65 mmol, 85% based on 1).

Anal. Calcd for C₁₈H₂₉FeN₂OPS (408.32 g/mol): C, 52.95; H, 7.16;

1

N, 6.86. Found: C, 53.17; H, 7.55; N, 6.30. H NMR (C₆D₆, δ): 0.99

O

DOI: 10.1021/acs.joc.7b00030

J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

Article

2

C₅H₄), 62.6 (C₅H₄), 62.7 (C₅H₄), 69.5 (C₅H₅), 117.4 (d, J_C,P= 4.3

Hz, C_C5H4−O). ³¹P{¹H} NMR (CDCl₃, δ): 2.5. HRMS (ESI-TOF)

m/z: [M]⁺calcd for C₂₄H₂₈Fe₂NO₃P 521.0501; found 521.0486.

Diferrocenyl 1H-Pyrrol-1-ylphosphonate (46). Ferrocenol (1, 836

mg, 4.14 mmol), BuLi (1.7 mL, 4.25 mmol), and dichloro(1H-pyrrol-

1-yl)phosphonate (2m, 380 mg, 2.07 mmol) were reacted according to

the general procedure described above. Puriﬁcation was realized by

column chromatography (silica, column size 2.5 × 12 cm) using a 98:2

dichloromethane/ethyl acetate mixture (v/v) as the eluent. Com-

pound 46 was obtained as an orange solid. Yield: 468 mg (0.91 mmol,

44% based on 1). Anal. Calcd for C₂₄H₂₂Fe₂NO₃P (515.10 g/mol): C,

55.96; H, 4.30; N, 2.72. Found: C. 55.48; H, 4.48; N, 2.67. Mp: 184

Anionic Phospho-Fries Rearrangement: General Procedure.

In a Schlenk tube, tetrahydrofuran (3 mL) and diisopropylamine

(amount see below) were placed, and the solution was cooled to −30

°C. Afterward, BuLi (amount see below) was added dropwise and the

mixture was stirred for 10 min at −30 °C. Depending on the reaction

temperature required for each rearrangement, the respective temper-

ature was adjusted. Afterward, the corresponding ferrocenyl phosphate

(1 equiv) was added in a single portion, and stirring was continued for

2−4 h. Dimethyl sulfate (see below for amount) was added in a single

portion, and the reaction mixture was allowed to warm to ambient

temperature, where stirring was continued overnight. All volatiles were

removed under reduced pressure. Puriﬁcation was realized using

column chromatography on silica or alumina (see below) using

diﬀerent solvent mixtures as eluents (see below).

Anionic Phospho-Fries Rearrangement of 6: Synthesis of 23

and 24. Phosphate 6 (70 mg, 0.131 mmol), diisopropylamine (0.11

mL, 0.783 mmol), BuLi (0.31 mL, 0.78 mmol), and dimethyl sulfate

(0.1 mL, 1.05 mmol) were reacted at 0 °C for 2 h, according to the

general procedure described above. Puriﬁcation was realized by

column chromatography (silica, column size 2.5 × 12 cm) using a 95:5

dichloromethane/ethyl acetate mixture (v/v) as the eluent, resulting in

the elution of two fractions. At ﬁrst, the phosphonate 23 was eluted

followed by the phosphinate 24.

1

°C. H NMR (CDCl₃, δ): 3.87−3.89 (m, 4 H, C₅H₄), 4.21 (s, 10 H,

C₅H₅), 4.27−4.28 (m, 2 H, C₅H₄), 4.30−4.31 (m, 2 H, C₅H₄), 6.40

4

(ddd, J_H,P= 4.7 Hz, J_H,H= 2.2 Hz, J_H,H= 2.2 Hz, 2 H, C3/4), 7.09

(ddd, J_H,H= 2.2 Hz, J_H,H= 2.2 Hz, ³J_H,P= 2.2 Hz, 2 H, C2/5). ¹³C{¹H}

NMR (CDCl₃, δ): 59.4 (d, J_C,P= 3.9 Hz, C₅H₄), 59.6 (d, J_C,P= 4.6 Hz,

3

C₅H₄), 62.96 (C₅H₄), 63.00 (C₅H₄), 69.7 (C₅H₅), 113.3 (d, J_C,P

=

11.5 Hz, C3/4), 117.3 (d, J_C,P= 4.5 Hz, C_C5H4−O), 122.8 (d, ²J_C,P

2

6.5 Hz, C2/5). ³¹P{¹H} NMR (CDCl₃, δ): −11.5. HRMS (ESI-TOF)

m/z: [M]⁺calcd for C₂₄H₂₂Fe₂NO₃P 515.0031; found 515.0014.

Diferrocenyl(1H-indol-1-yl)phosphonate (47). Ferrocenol (1, 836

mg, 4.14 mmol), BuLi (1.7 mL, 4.25 mmol), and dichloro(1H-indol-1-

yl) phosphonate (2n) (484 mg, 2.07 mmol) were reacted according to

the general procedure described above. Puriﬁcation was realized by

column chromatography (silica, column size 2.5 × 12 cm) using a 98:2

dichloromethane/ethyl acetate (v/v) mixture as the eluent. The title

compound was obtained as an orange solid. Crystals, suitable for

single-crystal X-ray diﬀraction analysis, were obtained by crystallization

from a boiling hexane solution containing 47. Yield: 945 mg (1.67

mmol, 81% based on 1). Anal. Calcd for C₂₈H₂₄Fe₂NO₃P (565.16 g/

mol): C, 59.51; H, 4.28; N, 2.48. Found: C, 59.51; H, 4.30; N, 2.60.

Mp: ∼25 °C. ¹H NMR (CDCl₃, δ): 3.82 (ddd, J_H,P= 2.7 Hz, J_H,H= 2.7

Hz, J_H,H= 1.5 Hz, 2 H, C₅H₄), 3.85 (ddd, J_H,P= 2.7 Hz, J_H,H= 2.7 Hz,

O,O′-Diferrocenyl(1-hydroxynaphth-2-yl)phosphonate (23). Or-

ange solid. Yield: 13 mg (0.024 mmol, 19% based on 6). Anal. Calcd

for C₃₀H₂₅Fe₂O₄P (592.18 g/mol): C, 60.85; H, 4.26. Found: C,

1

61.27; H, 4.56. Mp: 163−168 °C. H NMR (CDCl₃, δ): 3.83−3.84

(m, 2 H, C₅H₄), 3.85−3.86 (m, 2 H, C₅H₄), 4.19 (s, 10 H, C₅H₅),

4.30−4.31 (m, 2 H, C₅H₄), 4.38−4.39 (m, 2 H, C₅H₄), 7.32−7.40 (m,

2 H, H3/4), 7.54 (ddd, J_H,H= 8.2 Hz, J_H,H= 6.8 Hz, J_H,H= 1.2 Hz, 1

H, C₆H₄), 7.62 (ddd, J_H,H= 8.2 Hz, J_H,H= 6.9 Hz, J_H,H= 1.3 Hz, 1 H,

C₆H₄), 7.77 (d, J_H,H= 8.1 Hz, 1 H, C₆H₄), 8.40 (d, J_H,H= 8.3 Hz, 1 H,

C₆H₄), 10.99 (s, 1 H, OH). ¹³C{¹H} NMR (CDCl₃, δ): 59.6 (d, J_C,P

=

3.8 Hz, C₅H₄), 59.9 (d, J_C,P= 4.2 Hz, C₅H₄), 62.9 (C₅H₄), 63.0

2

(C₅H₄), 69.6 (C₅H₅), 99.5 (d, ¹J_C,P= 185.2 Hz, C1), 117.1 (d, J_C,P

=

J_H,H= 1.5 Hz, 2 H, C₅H₄), 4.13 (s, 10 H, C₅H₅₄), 4.15−4.16 (m, 2 H,

3

C₅H₄), 4.34−4.35 (m, 2 H, C₅H₄), 6.72 (ddd, J_H,P= 3.6 Hz, J_H,H

=

4.2 Hz, C_C5H4−O), 119.5 (d, J_C,P= 14.1 Hz, C4), 123.7 (C₆H₄), 124.8

4

3

2.7 Hz, J_H,H= 1.5 Hz, 1 H, H3), 7.29 (ddd, J_H,H= 8.1 Hz, J_H,H= 7.2

Hz, J_H,H= 1.0 Hz, 1 H, H5/6), 7.39 (ddd, J_H,H= 8.4 Hz, J_H,H= 7.2 Hz,

(d, J_C,P= 14.4 Hz, C8a), 125.4 (d, J_C,P= 6.4 Hz, C3), 126.2 (C₆H₄),

127.6 (C₆H₄), 129.5 (C₆H₄), 137.2 (d, ⁴J_C,P= 2.1 Hz, C4a), 161.5 (d,

²J_C,P= 8.1 Hz, C1). ³¹P{¹H} NMR (CDCl₃, δ): 17.7. HRMS (ESI-

3

J_H,H= 1.2 Hz, 1 H, H5/6), 7.46 (dd, J_H,H= 3.5 Hz, J_H,P= 2.1 Hz, 1

H, H2), 7.64−7.66 (m, 1 H, H4), 7.87 (d, J_H,H= 8.3 Hz, 1 H, C7).

¹³C{¹H} NMR (CDCl₃, δ): 59.3 (d, J_C,P= 3.8 Hz, C₅H₄), 59.6 (d, J_C,P

TOF) m/z: [M]⁺calcd for C₃₀H₂₅Fe₂O₄P 592.0185; found 592.0202.

O-Ferrocenyl(2-methoxyferrocenyl)(1-hydroxynaphth-2-yl)-

phosphinate (24). Orange solid. The compound was obtained in a

ratio of both diastereomers of 1:0.78. Crystals, suitable for single-

crystal X-ray diﬀraction analysis, were obtained by slow evaporation of

a hexane solution containing 24 at ambient temperature. Yield: 24 mg

(0.040 mmol, 30% based on 6). Anal. Calcd for C₃₁H₂₇Fe₂O₄P

(606.21 g/mol): C, 61.42; H, 4.49. Found: C, 61.58; H, 4.73. Mp:

= 4.5 Hz, C₅H₄), 62.95 (C₅H₄), 62.98 (C₅H₄), 69.6 (C₅H₅), 108.3 (d,

³J_C,P= 9.2 Hz, C3), 113.9 (C7), 117. Two (d, J_C,P= 4.0 Hz, C_C5H4

−

2

O), 121.3 (C4), 122.7 (C5/6), 123.9 (C5/6), 128.5 (d, ²J_C,P= 7.4 Hz,

3

2

C2), 131.1 (d, J_C,P= 10.9 Hz, C3a), 136.9 (d, J_C,P= 5.0 Hz, C7a).

³¹P{¹H} NMR (CDCl₃, δ): −11.6. HRMS (ESI-TOF) m/z: [M +

Na]⁺calcd for C₂₈H₂₄Fe₂NO₃P + Na 588.0086; found 588.0102.

Diferrocenyl 9H-Carbazol-9-yl phosphonate (48). Ferrocenol (1)

(835 mg, 4.13 mmol), BuLi (1.8 mL, 4.5 mmol), and 9H-carbazol-9-yl

dichloro phosphate (2o) (580 mg, 2.04 mmol) were reacted according

to the general procedure described above. Puriﬁcation was realized by

column chromatography (silica, column size 3.5 × 8 cm) using

dichloromethane as the eluent. Compound 48 was obtained as an

orange solid. Crystals, suitable for single-crystal X-ray diﬀraction

analysis, were obtained by crystallization from a boiling hexane

solution containing 48. Yield: 340 mg (0.553 mmol, 27% based on 1).

Anal. Calcd for C₃₂H₂₆Fe₂NO₃P (615.22 g/mol): C, 62.47; H, 4.26; N,

2.28. Found: C, 62.69; H, 4.40; N, 2.29. Mp: 160 °C. ¹H NMR

(CDCl₃, δ): 3.76 (ddd, J_H,H= 2.7 Hz, J_H,P= 2.7 Hz, J_H,H= 1.4 Hz, 2 H,

C₅H₄), 3.81 (ddd, J_H,H= 2.7 Hz, J_H,P= 2.7 Hz, J_H,H= 1.4 Hz, 2 H,

C₅H₄), 4.07 (s, 10 H, C₅H₅), 4.12−4.14 (m, 2 H, C₅H₄), 4.35−4.36

(m, 2 H, C₅H₄), 7.40 (ddd, J_H,H= 7.9 Hz, J_H,H= 7.3 Hz, J_H,H= 0.9 Hz,

2 H, C₁₂H₈N), 7.53 (ddd, J_H,H= 8.5 Hz, J_H,H= 7.2 Hz, J_H,H= 1.3 Hz, 2

H, C₁₂H₈N), 8.04−8.06 (m, 2 H, C₁₂H₈N), 8.17 (d, J_H,H= 8.4 Hz, 2

H, C₁₂H₈N). ¹³C{¹H} NMR (CDCl₃, δ): 59.3 (d, J_C,P= 4.1 Hz, C₅H₄),

59.5 (d, J_C,P= 4.8 Hz, C₅H₄), 62.89 (C₅H₄), 62.94 (C₅H₄), 69.5

1

194−196 °C. H NMR (CDCl₃, δ): 3.66 (s, 3 H, OCH₃, ma), 3.74−

3.76 (m, 1.7 H, ma, mi), 3.76−3.79 (m, 1.7 H, ma, mi), 3.86 (s, 2.1 H,

OCH₃, mi), 4.10 (dd, J_H,H= 2.8 H, J_H,H= 2.8 H, 0.7 H, C₅H₃, mi),

4.16 (dd, J_H,H= 2.6 H, J_H,H= 2.6 H, 1 H, C₅H₃, ma), 4.17−4.18 (m,

5.7 H, C₅H₅ma, C₅H_3/4mi), 4.19−4.21 (m, 9.5 H, C₅H₅ma, C₅H₅mi,

C₅H_3/4ma), 4.23 (ddd, J_H,H= 2.7 Hz, J_H,P= 2.2 Hz, J_H,H= 1.5 Hz, 0.7

H, C₅H₃mi), 4.26 (ddd, J_H,H= 2.8 Hz, J_H,P= 2.8 Hz, J_H,H= 1.5 Hz, 1

H, C₅H₃ma), 4.32 (ddd, J_H,H= 2.6 Hz, J_H,P= 2.6 Hz, J_H,H= 1.5 Hz, 0.7

H, C₅H₃mi), 4.36 (dddd, J = 2.7 Hz, J = 1.4 Hz, J = 1.4 Hz, J = 0.7 Hz,

1 H, ma), 4.42 (s, 3.5 H, C₅H₅, mi), 4.45 (dddd, J = 2.7 Hz, J = 1.4 Hz,

J = 1.4 Hz, J = 0.6 Hz, 0.7 H, mi), 4.51 (ddd, J_H,H= 2.8 Hz, J_H,H= 1.7

Hz, J_H,P= 1.7 Hz, 1 H, ma), 7.26 (dd, J_H,H= 8.5 Hz, J_H,P= 3.0 Hz, 0.7

H, H3/4 mi), 7.30 (dd, J_H,H= 8.6 Hz, J_H,P= 2.9 Hz, 1 H, H3/4 ma),

7.39 (dd, J_H,P= 12.8 Hz, J_H,H= 8.6 Hz, 0.7 H, H3/4 mi), 7.44 (dd, J_H,P

= 13.1 Hz, J_H,H= 8.6 Hz, 1 H, H3/4 ma), 7.48−7.52 (m, 1.7 H, ma,

mi), 7.54−7.58 (m, 1.7 H, ma, mi), 7.71 (d, J_H,H= 8.9 Hz, 0.7 H, mi),

7.73 (d, J_H,H= 8.6 Hz, 1 H, ma), 7.38 (d, J_H,H= 8.4 Hz, 0.7 H, mi),

8.42 (d, J_H,H= 8.4 Hz, 1 H, ma), 11.96 (s, 0.7 H, OH, mi), 11.99 (s, 1

H, OH, ma). ¹³C{¹H} NMR (CDCl₃, δ): 55.7* (d, J_C,P= 10.1 Hz,

C₅H₃), 55.8* (d, J_C,P= 10.2 Hz, C₅H₃), 58.3 (OCH₃), 58.3 (OCH₃),

59.9 (d, J_C,P= 4.3 Hz, C₅H₄), 60.0 (d, J_C,P= 4.1 Hz, C₅H₄), 60.1 (d,

J_C,P= 4.0 Hz, C₅H₄), 60.4 (d, J_C,P= 3.8 Hz, C₅H₄), 60.6 (C_C5H3−P, *),

60.9 (C_C5H3−P, *the second signal of the doublet overlaps), 62.68

2

(C₅H₅), 114.9 (C1, C8), 117.2 (d, J_C,P= 3.9 Hz, C_C5H4−O), 120.1,

122.8, 126.2 (d, J_C,P= 9.2 Hz, C4a, C4b), 127.0, 140.15 (d, J_C,P= 6.6

Hz, C8a, C9a). ³¹P{¹H} NMR (CDCl₃, δ): −11.8. HRMS (ESI-TOF)

m/z: [M]⁺calcd for C₃₂H₂₆Fe₂NO₃P 615.0345; found 615.0332.

P

DOI: 10.1021/acs.joc.7b00030

J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

Article

(C₅H₄), 62.76 (C₅H₄), 62.77 (C₅H₄), 62.9 (C₅H₄), 64.4 (d, J_C,P= 12.2

Hz, C₅H₃), 64.6 (d, J_C,P= 13.9 Hz, C₅H₃), 67.0* (d, J_C,P= 15.9 Hz,

C₅H₃), 67.3 (d, J_C,P= 10.8 Hz, C₅H₃), 69.48 (C₅H₅), 69.49 (C₅H₅),

(C5/6/7/8, mi), 128.71 (C5/6/7/8, ma), 133.8 (d, ²J_C,P= 9.9 Hz, C₁,

ma), 134.8 (d, ²J_C,P= 9.3 Hz, C₁, mi), 137.4 (C4a/C8a), 137.46 (C4a/

2

C8a), 137.48 (C4a/C8a), 157.4 (d, J_C,P= 6.1 Hz, C3, ma). ³¹P{¹H}

2

70.0 (C₅H₅), 70.2 (C₅H₅), 103.7 (C2, HMBC), 117.1 (d, J_C,P= 6.8

NMR (CDCl₃, δ): 42.6 (ma), 42.7 (mi). HRMS (ESI-TOF) m/z:

Hz, C_C5H4−O), 128.3 (d, ²J_C,P= 11.5 Hz, C_C5H3−O), 118.5* (d, J_C,P

=

[M]⁺calcd for C₃₁H₂₇Fe₂O₄P 606.0341; found 606.0316.

13.5 Hz, C₁₀H₆), 118.7* (d, J_C,P= 13.5 Hz, C₁₀H₆), 123.5* (C₁₀H₆),

123.68* (C₁₀H₆), 123.69* (C₁₀H₆), 125.5* (C₁₀H₆), 125.6* (C₁₀H₆),

125.62* (C₁₀H₆), 125.67* (C₁₀H₆), 126.2* (C₁₀H₆), 126.3* (C₁₀H₆),

127.3* (C₁₀H₆), 127.4* (C₁₀H₆), 128.1 (C_C5H3−O, HMBC), 128.5

(C_C5H3−O, HMBC), 136.5 (C4a/C8a, HMBC), 160.8 (C1, HMBC).

(*Obtained from DEPT90 measurements). ³¹P{¹H} NMR (CDCl₃,

δ): 44.6 (ma), 44.7 (mi). HRMS (ESI-TOF) m/z: [M + H]⁺calcd for

C₃₁H₂₇Fe₂O₄P + H 607.0373; found 607.0376.

Anionic Phospho-Fries Rearrangement of 7: Synthesis of 25

and 26a,b. Phosphate 7 (82 mg, 0.17 mmol), diisopropylamine (0.14

mL, 1.01 mmol), BuLi (0.41 mL, 1.03 mmol), and dimethyl sulfate

(0.3 mL, 3.15 mmol) were reacted at −80 °C (24) or 0 °C (25) for 2

h according to the general procedure described above. Puriﬁcation was

realized by column chromatography (silica, column size 2.5 × 12 cm)

using a 95:5 dichloromethane/ethyl acetate mixture (v/v) for 25 and

26b or a 2:3 dichloromethane/ethyl acetate mixture (v/v) for 26b as

the eluents.

O-Ferrocenyl(2-methoxyferrocenyl)(3-methoxy-2-naphthyl)-

phosphinate (26b). Compound 26b was obtained as an orange solid

with a dr of 1:0.97. Crystals, suitable for single-crystal X-ray diﬀraction

analysis, were obtained by slow evaporation of a hexane solution

containing 26b at ambient temperature. Yield: 20 mg (0.032 mmol,

19% based on 7). Anal. Calcd for C₃₂H₂₉Fe₂O₄P·5/6 C₆H₁₄(620.24·

5/6 86.18 g/mol): C, 64.22; H, 5.92. Found: C, 64.00; H, 6.14. Mp:

1

179 °C. H NMR (CDCl₃, δ): 3.57 (s, mi, 3 H, OCH₃(Fc)), 3.72−

3.76 (m, 4 H, C₅H₄), 3.77 (s, ma, 3 H, OCH₃(Fc)), 3.82 (s, ma, 3 H,

OCH₃(C₁₀H₆)), 3.91 (s, mi, 3 H, OCH₃(C₁₀H₆)), 4.02 (dd, mi, J_H,P

5.4 Hz, J_H,H= 2.7 Hz, 1 H, C₅H₃), 4.07 (dd, ma, J_H,P= 5.2 Hz, J_H,H

=

2.6 Hz, 1 H, C₅H₃), 4.02 (td, mi, J = 2.7 Hz, J = 1.5 Hz, 1 H, C₅H₃),

4.17−4.19 (m, 1 H, C₅H₃), 4.20 (s, 5 H, C₅H₅), 4.21 (s, 5 H, C₅H₅),

4.22−4.26 (m, 7 H, C₅H₅, C₅H₄, C₅H₃), 4.34−4.36 (m, 1 H, C₅H₄),

4.44−4.45 (m, 2 H, C₅H₃, C₅H₄), 4.47−4.48 (m, 6 H, C₅H₅, C₅H₄),

4

7.02 (d, J_H,P= 5.7 Hz, 1 H, H4), 7.12 (d, J_H,P= 5.8 Hz, 1 H, H4),

7.33−7.40 (m, 2 H, C₁₀H₇), 7.47 (ddd, ³J_H,H= 8.2 Hz, J_H,H= 6.9 Hz, J

= 1.3 Hz, 1 H, C₁₀H₇), 7.52 (ddd, ³J_H,H= 8.2 Hz, J_H,H= 6.9 Hz, J = 1.3

O,O′-Diferrocenyl(3-hydroxynaphth-2-yl)phosphonate (25). Or-

ange oil. Yield: 32 mg (0.066 mmol, 39% based on 7). Anal. Calcd for

C₃₀H₂₅Fe₂O₄P·0.25 CHCl₃₁(592.18·119.38 g/mol): C, 58.41; H, 4.09.

Found: C, 58.58; H, 4.43. H NMR (CDCl₃, δ): 3.85−3.88 (m, 4 H,

C₅H₄), 4.19 (s, 10 H, C₅H₅), 4.31−4.32 (m, 2 H, C₅H₄), 4.38−4.39

Hz, 1 H, C₁₀H₇), 7.67 (d, ³J_H,H= 8.2 Hz, 1 H, C₁₀H₇), 7.73 (d, ³J_H,H

=

8.2 Hz, 1 H, C₁₀H₇), 7.87 (d, J_H,H= 8.2 Hz, 1 H, C₁₀H₇), 7.90 (d, J_H,H

2

= 8.2 Hz, 1 H, C₁₀H₇), 8.60 (d, J_H,H= 15.7 Hz, 1 H, H1), 8.63 (d,

²J_H,P= 15.5 Hz, 1 H, H1). ¹³C{¹H} NMR (CDCl₃, δ): 55.0 (d, J_C,P

=

(m, 2 H, C₅H₄), 7.33−7.36 (m, 2 H, H4, H5/6/7/8), 7.51 (ddd, J_H,H

=

10.8, C₅H₃), 55.2 (s, OCH₃(C₁₀H₆)), 55.32 (d, J_C,P= 10.8, C₅H₃),

55.34 (s, OCH₃(C₁₀H₆)), 58.2 (s, OCH₃(Fc)), 58.3 (s, OCH₃(Fc)),

60.0 (d, ³J_C,P= 3.6 Hz, C2/5_C5H4), 60.2 (d, ¹J_C,P= 45.1 Hz, C−P), 60.4

(d, ³J_C,P= 3.7 Hz, C2/5_C5H4), 60.71 (d, ¹J_C,P= 164.4 Hz, C−P), 60.74

(d, ³J_C,P= 3.9 Hz, C2/5_C5H4), 60.8 (d, ³J_C,P= 4.3 Hz, C2/5_C5H4), 61.1

(d, ¹J_C,P= 166.2 Hz, C−P), 62.36 (s, C3/4_C5H4), 62.40 (s, C3/4_C5H4),

62.43 (s, C3/4_C5H4), 62.5 (s, C3/4_C5H4), 63.5 (d, J_C,P= 12.6 Hz,

C₅H₃), 63.9 (d, J_C,P= 13.7 Hz, C₅H₃), 67.3 (d, J_C,P= 16.5 Hz, C₅H₃),

67.8 (d, J_C,P= 10.4 Hz, C₅H₃), 69.35 (s, C₅H₅), 69.38 (s, C₅H₅), 70.0

(s, C₅H₅), 70.1 (s, C₅H₅), 105.6 (d, ³J_C,P= 7.3 Hz, C4), 105.8 (d, ³J_C,P

= 7.4 Hz, C4), 117.3 (d, ²J_C,P= 5.7 Hz, C_C5H4−O), 117.8 (d, ²J_C,P= 6.1

Hz, C_C5H4−O), 121.4 (d, ¹J_C,P= 133.2 Hz, C2), 122.0 (d, ¹J_C,P= 136.2

Hz, C2), 124.1 (C₁₀H₇), 124.2 (C₁₀H₇), 126.3 (C₁₀H₇), 126.4

(C₁₀H₇), 128.3 (C₁₀H₇), 128.5 (C₁₀H₇), 129.08 (C₁₀H₇), 129.14

(C₁₀H₇), 128.0 (d, ³J_C,P= 8.2 Hz, C4a), 128.1 (d, ³J_C,P= 8.1 Hz, C4a),

8.2 Hz, J_H,H= 6.8 Hz, J_H,H= 1.0 Hz, C₆H₄), 7.71 (d, J_H,H= 8.3 Hz,

3

C₆H₄), 7.80 (d, J_H,H= 8.2 Hz, C₆H₄), 8.08 (d, J_H,P= 17.0 Hz, H1),

9.70 (d, ⁴J_H,P= 0.9 Hz, OH). ¹³C{¹H} NMR (CDCl₃, δ): 59.7 (d, J_C,P

= 3.9 Hz, C₅H₄), 59.87 (d, J_C,P= 4.1 Hz, C₅H₄), 63.0 (C₅H₄), 63.1

2

(C₅H₄), 69.6 (C₅H₅), 112.1 (d, ³J_C,P= 11.9 Hz, C4), 117.2 (d, J_C,P

=

1

4.6 Hz, C_C5H4−O), 122.4 (d, J_C,P= 181.3 Hz, C2), 124.3 (C₆H₄),

126.7 (C₆H₄), 128.7 (C₆H₄), 129.2 (C₆H₄), 134.8 (d, J_C,P= 5.5 Hz,

2

C1), 138.0 (C4a/C8a), 139.6 (C4a/C8a), 156.6 (d, J_C,P= 7.8 Hz,

C3). ³¹P{¹H} NMR (CDCl₃, δ): 14.6. HRMS (ESI-TOF) m/z: [M]⁺

calcd for C₃₀H₂₅Fe₂O₄P 592.0185; found 592.0156.

O-Ferrocenyl(2-methoxyferrocenyl)(3-hydroxynaphth-2-yl) phos-

phinate (26a). Compound 26a was obtained as an orange oil with a

ratio of two diastereomers of 1:0.51. Yield: 45 mg (0.074 mmol, 44%

based on 7). Anal. Calcd for C₃₁H₂₇Fe₂O₄P (606.21 g/mol): C, 61.42;

H, 4.49. Found: C, 61.21; H, 4.94. Mp: >250 °C (decomp.) ¹H NMR

(CDCl₃, δ): 3.667 (s, 1.5 H, OCH₃, mi), 3.68 (d, J_H,H= 3.2 Hz, 1 H,

C₅H₃, ma), 3.75−3.77 (m, 1.5 H, C₅H_3/4, mi, ma), 3.78−3.81 (m, 1.5

H, C₅H_3/4, mi, ma), 3.88 (s, 3 H, OCH₃, ma), 4.10−4.12 (m, 1 H,

C₅H_3/4, ma), 4.17−4.20 (m, 11 H, C₅H₅ma, C₅H₅mi, C₅H_3/4mi),

4.21−4.23 (m, 1 H, C₅H_3/4, ma), 4.26−4.28 (m, 0.5 H, C₅H_3/4, mi),

4.34−4.35 (m, 1.5 H, C₅H_3/4, ma, mi), 4.43 (s, 5 H, C₅H₅, ma), 4.44−

4.46 (m, 1 H, C₅H_3/4, ma), 4.54−4.55 (m, 0.5 H, C₅H_3/4, mi), 7.26−

7−32 (m, 3 H, H4, H5/6/7/8, ma, mi), 7.42−7.48 (m, 1.5 H, H5/6/

7/8, ma, mi), 7.66 (d, J_H,H= 8.2 Hz, 1 H, H5/6/7/8, ma), 7.69 (d, J_H,H

129.3 (d, ²J_C,P= 7.6 Hz, C_C5H3−O), 129.9 (d, ²J_C,P= 13.1 Hz, C_C5H3

−

2

O), 136.76 (C8a), 136.77 (C8a), 137.7 (d, J_C,P= 7.3 Hz, C1), 138.2

(d, ²J_C,P= 7.2 Hz, C1), 157.3 (d, ²J_C,P= 4.3 Hz, C3−O), 157.5 (d, ²J_C,P

= 4.0 Hz, C3−O). ³¹P{¹H} NMR (CDCl₃, δ): 29.4 (ma), 33.5 (mi).

HRMS (ESI-TOF) m/z: [M]⁺calcd for C₃₂H₂₉Fe₂O₄P 620.0502;

found 620.0508.

1,3-Dioxa-2-((1R)-α-fenchyl)(oxo)phospha-[3](2,2′-dimethyl)-

ferrocenophane ((1R)-31). LiTMP (212 mg, 1.44 mmol) was

dissolved in 10 mL of tetrahydrofuran and cooled to −50 °C.

Compound 30 (150 mg, 0.36 mmol) was added in a single portion,

and stirring was continued for 4 h in a temperature range of −30 to

−10 °C. Dimethyl sulfate (0.3 mL, 3.2 mmol) was added in a single

portion, and the reaction mixture was allowed to warm to ambient

temperature. After 18 h, all volatiles were removed in vacuum.

Puriﬁcation was realized using column chromatography (silica, column

size 2 × 25 cm) and dichloromethane as the eluent. Compound 31

was obtained as an orange solid as a mixture of three diastereomers in

a ratio of 1:0.25:0.3. Single crystals, suitable for single-crystal X-ray

diﬀraction analysis, were obtained by slow evaporation of a hexane

solution containing 31 at ambient temperature. Yield: 84 mg (0.189

mmol, 53% based on (1R)-30). Anal. Calcd for C₂₂H₂₉FeO₄P (444.28

= 8.2 Hz, 0.5 H, H5/6/7/8, mi), 7.71 (d, J_H,H= 8.2 Hz, 1 H, H5/6/7/

3

8, ma), 7.75 (d, J_H,H= 8.3 Hz, 0.5 H, H5/6/7/8, mi), 8.07 (d, J_H,P

=

16.5 Hz, 1 H, H1, ma), 8.16 (d, ³J_H,P= 16.8 Hz, 0.5 H, H1, mi), 10.75

(d, ⁴J_H,P= 0.9 Hz, 1 H, OH, ma), 10.83 (d, ⁴J_H,P= 0.9 Hz, 0.5 H, OH,

mi). ¹³C{¹H} NMR (CDCl₃, δ): 55.89 (d, J_C,P= 10.5 Hz, C₅H₃, mi),

55.92 (d, J_C,P= 10.2 Hz, C₅H₃, ma), 58.3 (OCH₃, mi), 58.4 (OCH₃,

ma), 59.97 (d, ¹J_C,P= 167.3 Hz, C_C5H3−P, ma), 59.98 (d, J_C,P= 4.4 Hz,

C₅H₄, mi), 60.03 (d, J_C,P= 4.3 Hz, C₅H₄, ma), 60.05 (d, J_C,P= 3.9 Hz,

C₅H₄, mi), 60.3 (d, J_C,P= 4.0 Hz, C₅H₄, ma), 62.77 (C₅H₄, mi), 62.80

(C₅H₄, mi), 62.86 (C₅H₄, ma), 62.91 (C₅H₄, ma), 64.5 (d, J_C,P= 12.1

Hz, C₅H₃, mi), 64.8 (d, J_C,P= 13.9 Hz, C₅H₃, ma), 67.1 (d, J_C,P= 16.0

Hz, C₅H₃, ma), 67.4 (d, J_C,P= 10.9 Hz, C₅H₃, ma), 69.62 (C₅H₅, ma),

1

g/mol): C, 59.48; H, 6.58. Found: C, 59.46; H, 6.86. Mp: 84 °C. H

69.54 (C₅H₅, mi), 70.0 (C₅H₅, mi), 70.2 (C₅H₅, ma), 111.42 (d, ³J_C,P

8.6 Hz, C4, mi), 111.48 (d, J_C,P= 9.2 Hz, C4, ma), 115.6 (d, J_C,P

=

NMR (CDCl₃, δ): An assignment of the signals to hydrogen atoms is

hardly possible, due to an overlap of all three diastereomers and their

diﬀerent ratio. For spectra, see the Supporting Information. ¹³C{¹H}

3

1

132.0 Hz, C2, ma), 117.32 (C_C5H4−O), 117.33 (C_C5H4−O), 117.37

4

(C_C5H4−O), 123.61 (C5/6/7/8, ma), 123.65 (C5/6/7/8, mi), 126.49

NMR (CDCl₃, δ): 9.1 (d, J_C,P= 5.9 Hz, CH_3(C5H3)), 11.5 (d, J_C,P

=

2

(C5/6/7/8, ma), 126.55 (C5/6/7/8, mi), 127.2 (d, J_C,P= 14.6 Hz,

3.8 Hz, CH_3(C5H3)), 19.24 (CH₃), 19.26 (CH₃), 21.15 (CH₃), 21.17

(CH₃), 21.3 (CH₃), 25.96 (C5/6), 26.01 (C5/6), 26.32 (C5/6), 26.34

C_C5H3−O, ma), 128.4 (C5/6/7/8, ma), 128.6 (C5/6/7/8, mi), 128.65

Q

DOI: 10.1021/acs.joc.7b00030

J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

Article

(C5/6), 26.6 (C5/6), 29.59 (CH₃), 29.66 (CH₃), 29.71 (CH₃), 39.78

(C₅H₄), 65.66 (C₅H₄), 65.69 (C₅H₄), 67.02 (C₅H₄), 67.04 (C₅H₄),

69.3 (d, J_C,P= 15.0 Hz, C₅H₃), 69.4 (d, J_C,P= 14.0 Hz, C₅H₃), 109.06

(d, ²J_C,P= 11.8 Hz, C_C5H4−O), 109.12 (d, ²J_C,P= 12.1 Hz, C_C5H4−O),

130.5 (d, ²J_C,P= 10.5 Hz, C_C5H3−O). ³¹P{¹H} NMR (CDCl₃, δ): 30.1.

HRMS (ESI-TOF) m/z: [M + Na]⁺calcd for C₃₂H₂₈Fe₃O₈P₂+ Na

792.9202; found 792.9191.

(d, ³J_C,P= 2.6 Hz, C3), 39.80 (d, ³J_C,P= 2.4 Hz, C3), 39.85 (d, ³J_C,P

=

2.1 Hz, C3), 40.92 (C7), 40.97 (C7), 47.67 (C4), 47.74 (C4), 49.11

(d, ³J_C,P= 5.9 Hz, C1), 49.15 (d, ³J_C,P= 5.6 Hz, C1), 49.18 (d, ³J_C,P

5.6 Hz, C1), 60.14 (d, J_C,P= 8.7 Hz), 61.2 (d, J_C,P= 1.8 Hz), 61.3 (d,

J_C,P= 2.4 Hz), 64.08, 64.10, 64.14, 65.9, 66.55, 66.60, 67.4 (d, J_C,P

=

5.4 Hz), 68.1, 68.5 (d, J_C,P= 4.2 Hz), 68.6 (d, J_C,P= 4.1 Hz), 78.8 (d,

1,3-Dioxa-2-(2-methoxyferrocenyl) (oxo)phospha-[3]ferroceno-

phane (28a). Phosphate 27a (30 mg, 0.065 mmol), diisopropylamine

(0.04 mL, 0.27 mmol), BuLi (0.11 mL, 0.27 mmol), and dimethyl

sulfate (0.1 mL, 1.05 mmol) were reacted between −30 and −10 °C

for 2 h according to the general procedure described above.

Puriﬁcation was realized by column chromatography (silica, column

size 2.5 × 12 cm) using a 95:5 dichloromethane/ethyl acetate mixture

(v/v) as the eluent. The title compound 28a was obtained as an

orange solid. Yield: 31 mg (0.0.065 mmol, 99% based on 27a). Anal.

Calcd for C₂₁H₁₉Fe₂O₈P₂(478.04 g/mol): C, 52.76; H, 4.01. Found:

3

³J_C,P= 5.4 Hz, C_C5H3−CH₃), 78.95 (d, J_C,P= 5.9 Hz, C_C5H3−CH₃),

3

2

79.01 (d, J_C,P= 5.6 Hz, C_C5H3−CH₃), 94.5 (d, J_C,P= 8.0 Hz, C2),

2

94.6 (d, J_C,P= 7.9 Hz, C2), 94.9 (d, J_C₂_,P= 8.1 Hz, C2), 109.40 (d,

²J_C,P= 14.8 Hz, C_C5H3−O), 109.49 (d, J_C,P= 13.9 Hz, C_C5H3−O),

2

109.58 (d, J_C,P= 14.9 Hz, C_C5H3−O), 109.64 (d, J_C,P= 14.1 Hz,

C_C5H3−O), 110.8 (d, ²J_C,P= 13.0 Hz, C_C5H3−O), 111.0 (d, ²J_C,P= 13.1

Hz, C_C5H3−O). ³¹P{¹H} NMR (CDCl₃, δ): 0.77 (30%), 0.87 (25%),

0.96 (100%). HRMS (ESI-TOF) m/z: [M]⁺calcd for C₂₂H₂₉FeO₄P

444.1148; found 444.1118.

1

C, 52.02; H, 4.52. (*best match). Mp: >230 °C (decomp.). H NMR

(1R)-α-Fenchyl(1′-methoxyferrocenyl)methyl phosphate (32).

LiTMP (212 mg, 1.44 mmol) was dissolved in 10 mL of

tetrahydrofuran and cooled to −50 °C. Compound (1R)-30 (150

mg, 0.36 mmol) was added in a single portion, and the reaction

mixture was allowed to warm to ambient temperature. After being

stirred for 18 h, dimethyl sulfate (0.3 mL, 3.2 mmol) was added in a

single portion and stirring was continued for an additional 6 h. All

volatiles were removed in vacuum. Puriﬁcation was realized by column

chromatography (silica, column size 2 × 18 cm) using a 95:5

dichloromethane/ethyl acetate mixture (v/v) for the elution of 1,1′-

Fc(OMe)₂(18 mg, 0.073 mmol, 20% based on (1R)-30). Compound

32 was eluted using a 9:1 dichloromethane/ethyl acetate mixture (v/v)

as the eluent (R_f= 0.37). The title compound was obtained as an

orange oil as a mixture of two diastereomers in a 1:1 ratio. Yield: 17

mg (0.037 mmol, 10% based on (1R)-30). ¹H NMR (CDCl₃, δ): 0.89

(s, 3H, CH₃), 0.92 (s, 3 H, CH₃), 1.05−1.07 (m, 8 H, CH₃, H5/6),

1.10 (s, 3 H, CH₃), 1.13 (s, 3 H, CH₃), 1.15−1.16 (m, 1 H, H7),

1.18−1.19 (m, 1 H, H7), 1.41−1.46 (m, 2 H, H5/6), 1.49−1.52 (m, 2

H, H7), 1.69−1.71 (m, 6 H, H5/6, H4), 3.366 (s, 3 H, C−O−CH₃),

(CDCl₃, δ): 3.76 (s, 3 H, OCH₃), 4.00−4.01 (m, 2 H, C₅H₄), 4.07−

4.09 (m, 2 H, C₅H₄), 4.17 (dd, J_H,P= 5.9 Hz, J_H,H= 2.8 Hz, 1 H,

C₅H₃), 4.32−4.35 (m, 3 H, C₅H₄, C₅H₃), 4.40 (s, 5 H, C₅H₅), 4.41−

4.43 (m, 1 H, C₅H₃₁), 4.73−4.75 (m, 2 H, C₅H₄). ¹³C{¹H} NMR

(CDCl₃, δ): 52.9 (d, J_C,P= 228.6 Hz, C−P), 56.0 (d, J_C,P= 12.3 Hz,

C₅H₃), 58.5 (s, CH₃), 63.74 (d, J_C,P= 5.7 Hz, C₅H₄), 63.78 (d, J_C,P

=

5.6 Hz, C₅H₄), 63.9 (d, J_C,P= 6.2 Hz, C₅H₄), 64.9 (d, J_C,P= 15.3 Hz,

C₅H₃), 65.49 (C₅H₄), 65.52 (C₅H₄), 66.93 (C₅H₄), 67.2 (d, J_C,P= 14.1

Hz, C₅H₃), 70.5 (s, C₅H₅), 109.1 (d, ²J_C,P= 11.8 Hz, C_C5H4−O), 109.3

2

(d, J_C,P= 11.8 Hz, C_C5H4−O), 129.4 (d, J_C,P= 10.8 Hz, C_C5H3−O).

³¹P{¹H} NMR (CDCl₃, δ): 31.3. HRMS (ESI-TOF) m/z: [M + H]⁺

calcd for C₃₂H₂₈Fe₃O₈P₂+ H 770.9382; found 770.9391.

(R,R_p)-1,1′-Binaphthyl-2,2′-diyl(2-methoxyferrocenyl)phos-

phonate (28b). Phosphate 27b (100 mg, 0.188 mmol), diisopropyl

amine (0.16 mL, 1.15 mmol), BuLi (0.45 mL, 1.125 mmol), and

dimethyl sulfate (0.3 mL, 3.16 mmol) were reacted in tetrahydrofuran

at −70 °C for 2 h according to the general procedure described above.

Puriﬁcation was realized by column chromatography (silica, column

size 2 × 8 cm) using a 9:1 dichloromethane/ethyl acetate mixture (v/

v) as the eluent. Compound 28b was obtained as an orange solid with

a dr of both diastereomers of 1:0.045 (de = 0.91). Crystals, suitable for

single-crystal X-ray diﬀraction analysis, were obtained by crystallization

from a boiling chloroform solution containing 28b. Yield: 59 mg

(0.108 mmol, 57% based on 27b). Anal. Calcd for C₃₁H₂₃FeO₄P · 1/4

CH₂Cl₂(546.33 · 1/4 84.93 g/mol): C, 66.13; H, 4.17. Found: C,

3

3.370 (s, 3 H, C−O−CH₃), 3.808 (d, J_H,P= 11.3 Hz, 3 H, P−O−

CH₃), 3.815 (d, ³J_H,P= 11.3 Hz, 3 H, P−O−CH₃), 3.91−3.93 (m, 8 H,

C₅H₄), 3.99 (dd, ³J_H,P= 8.4 Hz, J_H,H= 1.9 Hz, 1 H, H2), 4.00 (dd, ³J_H,P

= 8.4 Hz, J_H,H= 1.8 Hz, 1 H, H2), 4.14−4.15 (m, 4 H, C₅H₄), 4.41

(dd, J_H,P= 3.5 Hz, J_H,P= 1.8 Hz, 1 H, C₅H₄), 4.42−4.43 (m, 2 H,

C₅H₄), 4.46 (dd, J_H,P= 3.3 Hz, J_H,P= 1.6 Hz, 1 H, C₅H₄). ¹³C{¹H}

NMR (CDCl₃, δ): 19.2 (CH₃), 20.74 (CH₃), 20.75 (CH₃), 25.62

(C5/6), 25.65 (C5/6), 25.89 (C5/6), 25.90 (C5/6), 29.8 (CH₃),

39.53 (C3), 39.55 (C3), 40.92 (C7), 47.9 (C4), 49.21 (C1), 49.22

(C1), 49.25 (C1), 49.26 (C1), 54.58 (P−O−CH₃), 54.60 (P−O−

CH₃), 54.63 (P−O−CH₃), 54.65 (P−O−CH₃), 56.31 (C₅H₄), 57.5

(C−O−CH₃), 60.29 (C₅H₄), 60.32 (C₅H₄), 60.35 (C₅H₄), 60.36

(C₅H₄), 60.37 (C₅H₄), 63.10 (C₅H₄), 63.12 (C₅H₄), 63.15 (C₅H₄),

63.15 (C₅H₄), 63.40 (C₅H₄), 63.41 (C₅H₄), 91.57 (C2), 91.60 (C2),

91.63 (C2), 91.66 (C2), 117.84 (C_C5H4−O−P), 117.85 (C_C5H4−O−

P), 117.88 (C_C5H4−O−P), 117.89 (C_C5H4−O−P), 128.1 (C_C5H4−O−

C). ³¹P{¹H} NMR (CDCl₃, δ): −3.95, −3.91. HRMS (ESI-TOF) m/

z: [M]⁺calcd for C₂₂H₂₉FeO₅P 462.1259; found 462.1246.

1

66.50; H, 4.37. Mp: >290 °C (decomp.). H NMR (CDCl₃, δ): 2.63

(s, 3 H, OCH₃), 4.10 (ddd, J_H,P= 3.2 Hz, J_H,H= 2.6 Hz, J_H,H= 1.5 Hz,

1 H, C₅H₃), 4.15 (ddd, J_H,P= 2.9 Hz, J_H,H= 2.8 Hz, J_H,H= 2.8 Hz, 1 H,

C₅H₃), 4.37 (s, 5 H, C₅H₅), 4.54 (ddd, J_H,H= 2.8 Hz, J_H,P= 2.2 Hz,

J_H,H= 1.5 Hz, 1 H, C₅H₃), 7.15 (dd, ³J_H,H= 8.8 Hz, ³J_H,P= 0.9 Hz, 1 H,

H3), 7.27−7.31 (m, 2 H, C₆H₄), 7.37−7.39 (m, 1 H, C₆H₄), 7.43−

3

7.49 (m, 3 H, C₆H₄), 7.73 (dd, J_H,H= 8.8 Hz, J_H,P= 8.8 Hz, 1 H,

3

H3′), 7.81 (d, J_H,H= 8.8 Hz, 1 H, H4), 7.87−7.89 (m, 1 H, C₆H₄),

3

7.96−7.97 (m, 1 H, C₆H₄), 8.06 (d, J_H,H= 8.8 Hz, 1 H, H4′).

¹³C{¹H} NMR (CDCl₃, δ): 51.1 (d, ¹J_C,P= 214.3 Hz, C_C5H3−P), 55.9

(d, J_C,P= 12.2 Hz, C₅H₃), 57.0 (s, OCH₃), 65.0 (d, J_C,P= 15.3 Hz,

C₅H₃), 67.7 (d, J_C,P= 15.9 Hz, C₅H₃), 70.5 (s, C₅H₅), 121.2 (d, ²J_C,P

=

meso-2,2′-Dimethoxy-1,1′-bis(1,3-dioxa-2-(oxo)phospha-[3]-

ferrocenophan-2-yl)-ferrocene (36). Phosphate 34 (36 mg, 0.067

mmol), diisopropylamine (0.04 mL, 0.27 mmol), BuLi (0.11 mL,

0.275 mmol), and dimethyl sulfate (0.05 mL, 0.527 mmol) were

reacted at −30 °C for 2 h according to the general procedure

described above. Puriﬁcation was realized by column chromatography

(silica, column size, 2 × 12 cm) using a 1:1 dichloromethane/ethyl

acetate (v/v) mixture as the eluent. The title compound was obtained

as an orange oil. Yield: 32 mg (0.042 mmol, 62% based on 34). Anal.

Calcd for C₃₂H₂₈Fe₃O₈P₂(770.04 g/mol): C, 49.91; H, 3.67. Found:

C, 53.46; H, 6.34. (*best match, too less compound) ¹H NMR

(CDCl₃, δ): 3.82 (s, 6 H, OCH₃), 4.01−4.02 (m, 4 H, C₅H₄), 4.08−

4.10 (m, 4 H, C₅H₄), 4.34−4.35 (m, 4 H, C₅H₄), 4.52 (dd, J_H,P= 6.0

Hz, J_H,H= 2.9 Hz, 2 H, C₅H₃), 4.66−4.68 (m, 4 H, C₅H₃), 4.71−4.72

(m, 2 H, C₅H₄), 4.73−4.74 (m, 2 H, C₅H₄). ¹³C{¹H} NMR (CDCl₃,

2

3

3.1 Hz, C3), 121.6 (d, J_C,P= 2.3 Hz, C3′), 121.8 (d, J_C,P= 2.4 Hz,

C1/C1′), 122.3 (d, ³J_C,P= 2.6 Hz, C1/C1′), 125.2, 125.4, 126.2, 126.5,

2

127.1, 127.2, 128.1, 128.4, 128.6 (d, J_C,P= 9.8 Hz, C_C5H3−O), 130.0

4

(d, J_C,P= 1.4 Hz, C4/C4′), 130.8 (d, J_C,P= 0.9 Hz, C4/C4′), 131.5

4

(d, J_C,P= 1.2 Hz, C4a/C4a′), 131.7 (d, J_C,P= 1.2 Hz, C4a/C4a′),

132.60 (C8a/C8a′), 132.61 (C8a/C8a′), 146.7 (d, ²J_C,P= 9.9 Hz, C2/

C2′), 147.5 (d, J_C,P= 10.0 Hz, C2/C2′). ³¹P{¹H} NMR (CDCl₃, δ):

2

33.7 (4.5%), 34.6 (95.5%). HRMS (ESI-TOF) m/z: [M]⁺calcd for

C₃₁H₂₃FeO₄P 547.0757; found 547.0764.

N,N,N′,N′-Tetraethyl-1-(2-methylferrocenyloxy)phosphinedia-

mine·BH₃(42). Compound 37 (519 mg, 1.33 mmol), s-BuLi (1.23 mL,

1.60 mmol), and MeI (0.16 mL, 2.60 mmol) were reacted according to

the general procedure between −20 and −10 °C for 3.5 h as described

above. Puriﬁcation was realized by column chromatography (alumina,

column size 3.5 × 13 cm) using a 8:2 hexane/diethyl ether mixture (v/

v) as the eluent. Compound 42 was obtained as a mixture in 436 mg

1

δ): 52.9 (d, J_C,P= 227.4 Hz, C−P), 58.4 (d, J_C,P= 12.1 Hz, C₅H₃),

58.6 (s, OCH₃), 63.78 (C₅H₄), 63.82 (C₅H₄), 63.86 (C₅H₄), 63.88

R

DOI: 10.1021/acs.joc.7b00030

J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

Article

consisting of the starting material 37 (91 mg, 0.24 mmol, 18%) and 42.

Both compounds could not be separated from each other by column

chromatography occurring in a ratio of 1:0.28. Yield: 343 mg (0.85

Hz, C3,C4−C₄N), 26.6 (d, ³J_C,P= 9.0 Hz, C3,C4−C₄N), 46.8 (d, ²J_C,P

= 5.1 Hz, C2,C5−C₄N), 60.9 (d, J_C,P= 1.8 Hz, C₅H₃), 61.4 (C₅H₃),

64.8 (C₅H₃), 69.4 (C₅H₄), 69.6 (C₅H₄), 71.2 (C₅H₄), 71.9 (C₅H₄),

mmol, 64% based on 37). ¹H NMR (C₆D₆, δ): 0.90 (t, ³J_H,H= 7.1 Hz,

73.9 (d, J_C,P= 5.0 Hz, C_C5H3−CH₃), 85.0 (C_C5H4−CH₃), 116.8 (d,

3

²J_C,P= 3.8 Hz, C_C5H3−O). ³¹P{¹H} NMR (C₆D₆, δ): 23.0. HRMS

6 H, CH₃), 1.01 (t, J_H,H= 7.1 Hz, 6 H, CH₃), 2.02 (s, 3 H, C_C5H3

−

3,4

(ESI-TOF) m/z: [M]⁺calcd for C₂₀H₂₉FeN₂O₂P 416.1311; found

416.1336.

CH₃), 2.87−3.00 (m, 8 H, CH₂), 3.62 (pt,

J

= 2.6 Hz, 1 H,

H,H

C₅H₄), 3.69−3.70 (m, 1 H, C₅H₄), 4.12 (s, 5 H, C₅H₅), 4.53 (dd, J_H,H

= 2.5 Hz, J_H,H= 1.5 Hz, 1 H, C₅H₄). ¹³C{¹H} NMR (C₆D₆, δ): 12.4

O-Ferrocenyl(2-methoxyferrocenyl)1H-pyrrol-1-ylphosphinate

(49). Phosphonate 46 (100 mg, 0.194 mmol), diisopropylamine (0.16

mL, 1.165 mmol), BuLi (0.46 mL, 1.15 mmol), and dimethyl sulfate

(0.11 mL, 1.16 mmol) were reacted according to the general

procedure for apFr at −70 °C for 4 h as described above. Puriﬁcation

was realized by column chromatography (silica, column size 2.5 × 15

cm) using dichloromethane for the elution of FcOMe (13 mg, 0.060

mmol, 31% based on 46), a 98:2 dichloromethane/ethyl acetate

mixture (v/v) for 46 (42 mg, 0.082 mmol, 42%) and a 95:5

dichloromethane/ethyl acetate mixture (v/v) for the elution of 49 as

the eluents. The title compound was obtained as a mixture of two

diastereomers in a ratio of 1:0.89 as an orange solid, which rapidly

decomposes in solution. Yield: 25 mg (0.047 mmol, 24% based on

46). Anal. Calcd for C₂₅H₂₄Fe₂NO₃P (529.13 g/mol): C, 56.75; H,

4.57; N, 2.65. Found: C, 57.34; H, 5.40; N, 2.10 (*best match). Mp:

182−188 °C. ¹H NMR (CDCl₃, δ): 3.70 (s, 3 H, OCH₃), 3.70 (s, 3 H,

OCH₃), 3.80−3.83 (m, 3 H, C₅H₄), 3.85 (ddd, J_H,H= 2.6 Hz, J_H,P= 2.6

Hz, J_H,H= 1.5 Hz, 1 H, C₅H₄), 4.08 (dd, J_H,P= 5.7 Hz, J_H,H= 2.8 Hz, 1

H, C₅H₃), 4.11−4.15 (m, 4 H, C₅H₄, C₅H₃), 4.19 (s, 5 H, C₅H₅), 4.20

(s, 5 H, C₅H₅), 4.21−4.22 (m, 1 H, C₅H₄), 4.23 (s, 5 H, C₅H₅), 4.27

(ddd, J_H,P= 3.2 Hz, J_H,H= 2.8 Hz, J_H,H= 1.5 Hz, 1 H, C₅H₃), 4.28−

4.30 (m, 1 H, C₅H₃), 4.33−4.34 (m, 1 H, C₅H₄), 4.38 (s, 5 H, C₅H₅),

4.43 (ddd, J_H,H= 2.8 Hz, J_H,P= 2.0 Hz, J_H,H= 1.4, 1 H, C₅H₃), 6.30−

6.32 (m, 2 H, H3,4), 6.34−6.36 (m, 2 H, H3,4), 7.15−7.16 (m, 2 H,

4

(C_C5H3−CH₃), 14.2 (d, J_C,P= 1.7 Hz, CH₃), 14.5 (d, J_C,P= 1.7 Hz,

CH₃), 39.3 (d, ³J_C,P= 6.4 Hz, CH₂), 39.5 (d, ³J_C,P= 6.4 Hz, CH₂), 60.7

(C₅H₃), 60.95 (d, J_C,P= 3.0 Hz, C₅H₃), 64.5 (C₅H₃), 70.3 (C₅H₅),

74.6 (d, ³J_C,P= 2.6 Hz, C_C5H3−CH₃), 117.4 (d, ²J_C,P= 1.8 Hz, C_C5H3

−

O). ³¹P{¹H} NMR (C₆D₆, δ): 130.8−131.7 (br m). ¹¹B{¹H} NMR

1

(C₆D₆, δ): −39.6 (d, J_B,P= 91.3 Hz). HRMS (ESI-TOF) m/z: [M +

Na]⁺calcd for C₁₉H₃₄BFeN₂OP + Na 427.1747; found 427.1724.

N,N,N′,N′-Tetraethyl-1-(2-methylferrocenyloxy)phosphinedia-

mine sulﬁde (43). Compound 38 (250 mg, 0.61 mmol), s-BuLi (0.75

mL, 0.98 mmol), and MeI (0.10 mL, 1.59 mmol) were reacted

according to the general procedure between −20 and −10 °C for 3.5 h

as described above. Puriﬁcation was realized by column chromatog-

raphy (alumina, column size 2.5 × 17 cm) using an 85:15 hexane/

dichloromethane mixture (v/v) as the eluent. Compound 43 was

obtained in a mixture of 135 mg along with the starting material 38.

Both compounds could not be separated from each other by column

chromatography occurring in a ratio of 1:0.07. Yield: 128 mg (0.302

mmol, 50% based on 38). ¹H NMR (C₆D₆, δ): 0.97 (t, ³J_H,H= 7.1 Hz,

3

6 H, CH₃), 1.06 (t, J_H,H= 7.1 Hz, 6 H, CH₃), 2.04 (s, 3 H, C_C5H3

−

3,4

CH₃), 2.99−3.11 (m, 8 H, CH₂), 3.64 (pt,

J

= 2.6 Hz, 1 H,

H,H

C₅H₃), 3.71−3.72 (m, 1 H, C₅H₃), 4.14 (s, 5 H, C₅H₅), 4.61−4.62 (m,

1 H, C₅H₃). ¹³C{¹H} NMR (C₆D₆, δ): 12.5 (C_C5H3−CH₃), 14.1 (d,

⁴J_C,P= 3.3 Hz, CH₃), 14.4 (d, ⁴J_C,P= 3.0 Hz, CH₃), 40.6 (d, ³J_C,P= 5.0

3

H2,5), 7.26−7.28 (m, 2 H, H2,5). ¹³C{¹H} NMR (CDCl₃, δ): 55.7 (d,

Hz, CH₂), 40.9 (d, J_C,P= 5.1 Hz, CH₂), 60.9 (C₅H₃), 61.0 (d, J_C,P

=

3

1

3.0 Hz, C₅H₃), 64.5 (C₅H_{2 3}), 70.3 (C₅H₅), 74.9 (d, J_C,P= 4.0 Hz,

C_C5H3−CH₃), 116.8 (d, J_C,P= 1.3 Hz, C_C5H3−O). ³¹P{¹H} NMR

(C₆D₆, δ): 90.9. HRMS (ESI-TOF) m/z: [M]⁺calcd for

C₁₉H₃₁FeN₂OPS 422.1239; found 422.1262.

J_C,P= 11.6 Hz, C₅H₃), 55.9 (d, J_C,P= 11.7 Hz, C₅H₃), 57.1 (d, J_C,P

=

1

207.7 Hz, C−P), 57.9 (d, J_C,P= 206.3 Hz, C−P), 58.24 (OCH₃),

58.25 (OCH₃), 59.74 (d, J_C,P= 3.8 Hz, C₅H₄), 59.77 (d, J_C,P= 3.7 Hz,

C₅H₄), 59.82 (d, J_C,P= 4.1 Hz, C₅H₄), 60.1 (d, J_C,P= 3.7 Hz, C₅H₄),

62.76 (C₅H₄), 62.83 (C₅H₄), 62.85 (C₅H₄), 64.3 (d, J_C,P= 14.2 Hz,

C₅H₃), 64.6 (d, J_C,P= 15.1 Hz, C₅H₃), 66.8 (d, J_C,P= 15.8 Hz, C₅H₃),

67.8 (d, J_C,P= 13.2 Hz, C₅H₃), 69.58 (C₅H₅), 69.60 (C₅H₅), 70.0

(C₅H₅), 70.3 (C₅H₅), 112.05 (d, ³J_C,P= 9.7 Hz, C3,4), 112.13 (d, ³J_C,P

= 10.0 Hz, C3,4), 116.73 (d, ²J_C,P= 7.3 Hz, C_C5H4−O), 116.76 (d, ²J_C,P

(2-Methylferrocenyl)di(pyrrolidin-1-yl)phosphinate (44) and

(1′,2-Dimethylferrocenyl)di(pyrrolidinin-1-yl)phosphinate (45).

Compound 39 (206 mg, 0.53 mmol) was dissolved in hexane (A)/

diethyl ether (B) and cooled to −30 °C, and s-BuLi (0.54 mL, 0.69

mmol) was dropwise added. The mixture was stirred for 18 h at

ambient temperature (A) or 4 h between −40 and −30 °C (B).

Afterward, MeI (0.10 mL, 1.59 mmol) was added in a single portion,

and the reaction mixture was allowed to warm to ambient temperature,

where stirring was continued for 18 h. Puriﬁcation was realized by

column chromatography (alumina, column size 2.5 × 17 cm) using a

9:1 dichloromethane/ethyl acetate mixture (v/v) as the eluent. The

title compounds 44 and 45 were obtained as mixtures (A, 39/44/45 =

0.24:1:<0.05; B, 39/44/45 = 0.06:1:0.65) and could not be separated

from each other by column chromatography.

= 7.1 Hz, C_C5H4−O), 122.3 (d, ²J_C,P= 6.2 Hz, C2,5), 122.5 (d, ²J_C,P

=

2

6.3 Hz, C2,5), 128.1 (d, J_C,P= 11.1 Hz, C_C5H3−O), 128.7 (d, J_C,P

9.9 Hz, C_C5H3−O). ³¹P{¹H} NMR (CDCl₃, δ): 17.8 (major), 18.3

(minor). HRMS (ESI-TOF) m/z: [M

C₂₅H₂₄Fe₂NO₃P + H 530.0266; found 530.0269.

+

H]⁺calcd for

O,O′-Diferrocenyl(1H-pyrrol-2-yl)phosphonate (52). Phosphonate

46 (100 mg, 0.194 mmol), diisopropylamine (0.16 mL, 1.165 mmol),

BuLi (0.46 mL, 1.15 mmol), and dimethyl sulfate (0.11 mL, 1.16

mmol) were reacted according to the general procedure for apFr at

−40 °C for 4 h as described above. Puriﬁcation was realized by column

chromatography (silica, column size 2.5 × 15 cm) using a 98:2

dichloromethane/ethyl acetate mixture (v/v) as the eluent. Com-

pound 52 was obtained as a yellow, weakly soluble solid. Thus, the

sample was suspended in DMSO-d₆and 10% CDCl₃was added to

optimize the solubility. Yield: 27 mg (0.052 mmol, 27% based on 46).

Anal. Calcd for C₂₄H₂₂Fe₂NO₃P (515.10 g/mol): C, 55.96; H, 4.30; N,

Compound 44. Yield: A, 137 mg (0.34 mmol, 64% based on 39);

B, 102 mg (0.25 mmol, 48% based on 39). ¹H NMR (C₆D₆, δ): 1.37−

1.40 (m, 4 H, H3,H4−C₄N), 1.48−1.51 (m, 4 H, H3,H4−C₄N), 2.06

(s, 3 H, CH₃), 3.05−3.13 (m, 4 H, H2,H5−C₄N), 3.16−3.20 (m, 4 H,

H2,H5−C₄N), 3.66−3.67 (m, 1 H, C₅H₃), 3.71−3.74 (m, 1 H, C₅H₃),

4.19 (s, 5 H, C₅H₅), 4.75−4.77 (m, 1H, C₅H₃). ¹³C{¹H} NMR (C₆D₆,

δ): 12.1 (CH₃), 26.5 (d, ³J_C,P= 8.7 Hz, C3,C4−C₄N), 26.6 (d, ³J_C,P

=

2

1

9.0 Hz, C3,C4−C₄N), 46.8 (d, J_C,P= 4.6 Hz, C2,C5−C₄N), 60.2 (d,

J_C,P= 1.9 Hz, C₅H₃), 60.7 (C₅H₃), 64.3 (C₅H₃), 70.5 (C₅H₅), 74.0 (d,

2.72. Found: C. 55.71; H, 4.25; N, 2.82. Mp: >250 °C. H NMR

(CDCl₃, δ): 3.87 (br, m, 4 H, C₅H₄), 4.20 (br, m, 10 H, C₅H₅), 4.34

(br, m, 4 H, C₅H₄), 6.35 (br, m, 1 H, C₄H₄N), 6.84 (br, m, 1 H,

C₄H₄N), 7.06 (br, m, 1 H, C₄H₄N), 9.08 (br, s, 1 H, NH). ¹³C{¹H}

NMR (CDCl₃, δ): 59.9 (d, J_C,P= 3.7 Hz, C₅H₄), 60.1 (d, J_C,P= 4.0 Hz,

C₅H₄), 62.8 (C₅H₄), 62.9 (C₅H₄), 69.6 (C₅H₅). ³¹P{¹H} NMR

2

³J_C,P= 5.3 Hz, C_C5H3−CH₃), 117.2 (d, J_C,P= 4.0 Hz, C_C5H3−O).

³¹P{¹H} NMR (C₆D₆, δ): 22.9. HRMS (ESI-TOF) m/z: [M]⁺calcd

for C₁₉H₂₇FeN₂O₂P 402.1154; found 402.1158.

Compound 45. Yield: A, 7 mg (0.017 mmol, 3% based on 39); B,

1

69 mg (0.165 mmol, 31% based on 39). H NMR (C₆D₆, δ): 1.37−

(CDCl₃, δ): 4.3. H NMR (DMSO-d₆, δ): 3.87 (br, m, 4 H, C₅H₄),

1.40 (m, 4 H, H3,H4−C₄N), 1.48−1.51 (m, 4 H, H3,H4−C₄N), 2.03

4.14 (br, m, 10 H, C₅H₅), 4.31 (br, m, 4 H, C₅H₄), 6.24 (br, m, 1 H,

C₄H₄N), 6.80 (br, m, 1 H, C₄H₄N), 7.13 (br, m, 1 H, C₄H₄N), 11.93

(br, s, 1 H, NH). ¹³C{¹H} NMR (DMSO-d₆, δ): 59.3* (d, J_C,P= 3.9

(s, 3 H, CH₃), 2.06 (s, 3 H, CH₃), 3.05−3.15 (m, 4 H, H2,H5−C₄N),

3,4

3.17−3.21 (m, 4 H, H2,H5−C₄N), 3.64 (pt,

J

= 2.6 Hz, 1 H,

H,H

C₅H₃), 3.66−3.70 (m, 1 H, C₅H_3/4), 4.00−4.02 (m, 1 H, C₅H₃), 4.08−

4.11 (m, 3 H, C₅H₄), 4.71 (dd, J = 2.2 Hz, J_H,H= 1.8 Hz, 1 H, C₅H₃).

¹³C{¹H} NMR (C₆D₆, δ): 11.8 (CH₃), 13.9 (CH₃), 26.5 (d, ³J_C,P= 8.7

Hz, C₅H₄), 59.4* (d, J_C,P= 4.5 Hz, C₅H₄), 62.3 (C₅H₄), 62.4 (C₅H₄),

1

69.1 (C₅H₅), 109.2* (d, J_C,P= 16.1 Hz, C₄H₃N), 114.7 (d, J_C,P

=

235.8 Hz, C1_C4H3N−P), 116.6 (d, ²J_C,P= 4.8 Hz, C_C5H4−O), 120.2* (d,

S

DOI: 10.1021/acs.joc.7b00030

J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

Article

J_C,P= 20.2 Hz, C₄H₃N), 125.3* (d, J_C,P= 13.5 Hz, C₄H₃N). ³¹P{¹H}

NMR (DMSO-d₆, δ): 4.5. (*Obtained from DEPT90 measurements).

HRMS (ESI-TOF) m/z: [M + Na]⁺calcd for C₂₄H₂₂Fe₂NO₃P + Na

537.9929; found 537.9913.

J

_H,H= 7.3 Hz, J_H,H= 1.0 Hz, 2 H, C₁₂H₈, ma), 7.34 (ddd, J_H,H= 7.9 Hz,

J_H,H= 7.3 Hz, J_H,H= 1.0 Hz, 0.6 H, C₁₂H₈, mi), 7.40 (ddd, J_H,H= 8.5

Hz, J_H,H= 7.2 Hz, J_H,H= 1.3 Hz, 2 H, C₁₂H₈, ma), 7.45 (ddd, J_H,H= 8.5

Hz, J_H,H= 7.2 Hz, J_H,H= 1.4 Hz, 0.6 H, C₁₂H₈, mi), 7.96−7.98 (m, 2

H, C₁₂H₈, ma), 8.02−8.04 (m, 0.6 H, C₁₂H₈, mi), 8.16−8.17 (m, 2 H,

C₁₂H₈, ma), 8.28−8.30 (m, 0.6 H, C₁₂H₈, mi). ¹³C{¹H} NMR (CDCl₃,

δ): 55.8 (d, J_C,P= 11.2 Hz, C₅H₃, mi), 56.0 (d, J_C,P= 12.0 Hz, C₅H₃,

ma), 58.3 (s, OCH₃, ma), 58.4 (s, OCH₃, mi), 58.5 (d, J_C,P= 206.1

Hz, C−P, ma), 59.8 (d, J_C,P= 4.1 Hz, C₅H₄, ma), 60.0 (d, J_C,P= 4.0

Hz, C₅H₄, ma), 60.3 (d, J_C,P= 3.7 Hz, C₅H₄, mi), 62.7 (C₅H₄, mi),

62.8 (C₅H₄, mi), 62.82 (C₅H₄, ma), 62.84 (C₅H₄, ma), 64.1 (d, J_C,P

15.1 Hz, C₅H₃, mi), 64.2 (d, J_C,P= 13.8 Hz, C₅H₃, ma), 66.5 (d, J_C,P

15.6 Hz, C₅H₃, mi), 67.0 (d, J_C,P= 11.6 Hz, C₅H₃, ma), 69.47 (C₅H₅,

ma), 69.52 (C₅H₅, mi), 70.27 (C₅H₅, mi), 70.29 (C₅H₅, ma), 115.3

(CH, ma), 115.4 (CH, mi), 116.6 (d, J_C,P= 7.5 Hz, C_C5H4−O, ma),

119.6 (CH, ma), 119.7 (CH, mi), 121.8 (CH, ma), 122.1 (CH, mi),

O-Ferrocenyl(1H-indol-1-yl)(2-methoxyferrocenyl)phosphinate

(50). Compound 47 (100 mg, 0.177 mmol), diisopropylamine (0.15

mL, 1.06 mmol), BuLi (0.43 mL, 1.08 mmol), and dimethyl sulfate

(0.10 mL, 1.06 mmol) were reacted at −40 °C for 3 h according to the

general procedure described above. Puriﬁcation was realized by

column chromatography (silica, column size 2.5 × 22 cm) using a 95:5

dichloromethane/ethyl acetate mixture (v/v) as the eluent. Com-

pound 50 was obtained along with compound 53 in a ratio of 1:0.78

(53/50) as a mixture of two diastereomers. Crystals, suitable for

single-crystal X-ray diﬀraction analysis, were obtained by evaporation

of a CHCl₃solution containing the mixture of 53 or 50 at ambient

temperature. Yield: 25 mg (0.043 mmol, 24% based on 47). ¹H NMR

(CDCl₃, δ): 3.56 (s, 3 H, OCH₃), 3.77−3.79 (m, 2 H, C₅H₄), 3.80−

3.81 (m, 5 H, OCH₃, C₅H₄), 3.95−3.96 (m, 1 H, C₅H₃), 4.00−4.02

(m, 1 H, C₅H₃), 4.12−4.14 (m, 6 H, C₅H₅, C₅H₃), 4.17−4.19 (m, 7 H,

C₅H₅, C₅H₄), 4.22−4.24 (m, 1 H, C₅H₃), 4.28−4.29 (m, 1 H, C₅H₃),

4.30−4.32 (m, 6 H, C₅H₅, C₅H₄), 4.35 (s, 5 H, C₅H₅), 4.40−4.42 (m,

1 H, C₅H₄), 4.48−4.49 (m, 1 H, C₅H₃), 6.64 (ddd, ³J_H,H= 3.5 Hz, ⁴J_H,P

= 2.6 Hz, J_H,H= 0.8 Hz, 1 H, H3), 6.66 (ddd, ³J_H,H= 3.4 Hz, ⁴J_H,P= 2.6

Hz, J_H,H= 0.8 Hz, 1 H, H3), 7.16−7.17 (m, 1 H, H4), 7.18−7.20 (m, 1

H, H4), 7.20−7.23 (m, 2 H, H5/6), 7.25−7.28 (m, 2 H, H5/6), 7.53

(dd, ³J_H,H= 3.5 Hz, ⁴J_H,P= 2.8 Hz, 1 H, H2), 7.55 (dd, ³J_H,H= 3.5 Hz,

⁴J_H,P= 2.8 Hz, 1 H, H2), 7.92 (dd, ³J_H,H= 8.1 Hz, J_H,H= 1.2 Hz, 1 H,

1

=

2

126.15 (d, J_C,P= 7.2 Hz, C_C5H3−O, ma), 126.22 (CH, ma), 126.4

3

2

(CH, mi), 129.4 (d, J_C,P= 12.6 Hz, 4a/ab, ma), 140.7 (d, J_C,P= 5.6

Hz, 8a/9a, ma), 141.0 (d, J_C,P= 5.5 Hz, 8a/9a, ma). ³¹P{¹H} NMR

2

(CDCl₃, δ): 17.0 (ma), 19.3 (mi). HRMS (ESI-TOF) m/z: [M]⁺calcd

for C₃₃H₂₈Fe₂NO₃P 629.0501; found 629.0510.

O,O′-Diferrocenyl (1H-indol-2-yl)phosphonate (53) (A). Com-

pound 47 (100 mg, 0.177 mmol), diisopropylamine (0.15 mL, 1.06

mmol), BuLi (0.43 mL, 1.08 mmol), and dimethyl sulfate (0.10 mL,

1.06 mmol) were reacted at −40 °C for 3 h according to the general

procedure described above. Puriﬁcation was realized by column

chromatography (silica, column size 2.5 × 22 cm) using a 95:5

dichloromethane/ethyl acetate mixture (v/v) as the eluent. Com-

pound 53 was obtained in a mixture with compound 50 of ratio 1:0.78

H7), 8.02 (dd, ³J_H,H= 8.1 Hz, J_H,H= 8.1 Hz, J_H,H= 1.1 Hz, 1 H, H7).

¹³C{¹H} NMR (CDCl₃, δ): 55.8 (d, J_C,P= 11.4 Hz, C₅H₃), 56.0 (d, J_C,P

1

= 11.8 Hz, C₅H₃), 57.5 (d, J_C,P= 207.5 Hz, C−P), 57.7 (d, J_C,P

=

(53/B). Yield: 31 mg (0.055 mmol, 31% based on 47). H NMR

206.4 Hz, C−P), 58.28 (OCH₃), 58.31 (OCH₃), 59.8−60.2 (m,

C₅H₄), 62.79 (C₅H₄), 62.81 (C₅H₄), 62.83 (C₅H₄), 64.4 (d, J_C,P= 13.6

Hz, C₅H₃), 64.5 (d, J_C,P= 14.9 Hz, C₅H₃), 66.7 (d, J_C,P= 16.0 Hz,

C₅H₃), 67.3 (d, J_C,P= 12.3 Hz, C₅H₃), 69.5 (C₅H₅), 69.54 (C₅H₅),

70.1 (C₅H₅), 70.3 (C₅H₅), 107.0 (d, ³J_C,P= 7.4 Hz, C3), 107.4 (d, ³J_C,P

(CDCl₃, δ): 3.86−3.87 (m, 4 H, C₅H₄), 4.21 (s, 10 H, C₅H₅), 4.36−

4.38 (m, 2 H, C₅H₄), 4.38−4.40 (m, 2 H, C₅H₄), 7.16−7.18 (m, 1 H,

H3), 7.33 (ddt, ³J_H,H= 8.1 Hz, J_H,H= 7.0 Hz, J_H,H= 1.0 Hz, 1 H, H5/

H6), 7.46 (dd, ³J_H,H= 8.4 Hz, J_H,H= 1.1 Hz, 1 H, H7), 7.57−7.60 (m,

1 H, H5/H6), 7.70 (dd, ³J_H,H= 8.1 Hz, J_H,H= 1.1 Hz, 1 H, H4), 9.01

(s, 1 H, NH). ¹³C{¹H} NMR (CDCl₃, δ): 59.9−60.1 (m, C₅H₄), 62.9

2

= 7.5 Hz, C3), 114.3 (C7), 114.5 (C7), 116.7 (d, J_C,P= 7.0 Hz,

2

4

C_C5H4−O), 116.9 (d, J_C,P= 7.5 Hz, C_C5H4−O), 120.9, 121.8, 121.9,

(d, J_C,P= 4.5 Hz, C₅H₄), 69.6 (C₅H₅), 112.1 (d, J_C,P= 1.9 Hz, C7),

122.2, 123.0, 123.2, 128.1 (d, ²J_C,P= 6.6 Hz, C2), 128.6 (d, ²J_C,P= 6.4

Hz, C2), 128.8 (d, ²J_C,P= 9.7 Hz, C_C5H3−O), 128.9 (d, ²J_C,P= 11.9 Hz,

2

113.7 (d, J_C,P= 17.5 Hz, C3), 117.2 (d, J_C,P= 4.9 Hz, C_C5H4−O),

1

120.8 (C5/6), 122.1 (C4), 122.0 (d, J_C,P= 227.4 Hz, C_C2−P), 125.1

3

C_C5H3−O), 130.9 (d, J_C,P= 8.3 Hz, C3a), 131.1 (d, J_C,P= 8.6 Hz,

(C5/6), 127.5 (d, J_C,P= 16.5 Hz, C3a), 138.2 (d, J_C,P= 13.0 Hz,

C7a). ³¹P{¹H} NMR (CDCl₃, δ): 4.0. HRMS (ESI-TOF) m/z: [M +

H]⁺calcd for C₂₈H₂₄Fe₂NO₃P + H 566.0266; found 566.0295.

Crystal Data for 53: C₂₈H₂₄Fe₂NO₃P × CHCl₃, M = 684.52 g

mol⁻¹, crystal dimensions 0.40 × 0.20 × 0.02 mm, monoclinic, P21/n,

λ = 0.71073 Å, a = 14.5249(6) Å, b = 10.2459(5) Å, c = 19.6024(8) Å,

β = 107.309(4)°, V = 2785.1(2) Å³, Z = 4, ρ_calcd= 1.632 Mg m⁻³, μ =

1.420 mm⁻¹, T = 115.00(10) K, θ range 2.991−24.998°, 17 335

reﬂections collected, 4887 independent reﬂections (R_int= 0.0506), R₁

= 0.0468, wR₂= 0.1069 (I > 2σ(I)).

2

C3a), 137.3 (d, J_C,P= 5.0 Hz, C7a), 137.7 (d, J_C,P= 4.6 Hz, C7a).

³¹P{¹H} NMR (CDCl₃, δ): 16.8, 18.2. HRMS (ESI-TOF) m/z: [M +

H]⁺calcd for C₂₉H₂₆Fe₂NO₃P + H 580.0423; found 580.0430.

O-Ferrocenyl 9H-Carbazol-9-yl(2-methoxyferrocenyl)phos-

phinate (51). Compound 48 (100 mg, 0.163 mmol), diisopropyl-

amine (0.14 mL, 0.98 mmol), BuLi (0.39 mL, 0.98 mmol), and

dimethyl sulfate (0.09 mL, 0.98 mmol) were reacted at −60 °C for 3 h

according to the general procedure described above. Puriﬁcation was

realized by column chromatography (silica, column size 2.5 × 16 cm)

using a 95:5 dichloromethane/ethyl acetate mixture (v/v) as the

eluent. The title compound was obtained as an orange solid and as a

mixture of both diastereomers in a ratio of 1:0.28 (de = 0.56). Crystals,

suitable for single-crystal X-ray diﬀraction analysis, were obtained by

evaporation of a dichloromethane solution at ambient temperature

containing 51. Yield: 58 mg (0.092 mmol, 56% based on 48). Anal.

Calcd for C₃₃H₂₈Fe₂NO₃P (629.24 g/mol): C, 62.99; H, 4.49; N, 2.23.

Found: C. 62.98; H, 4.56; N, 2.25. Mp: 206 °C. ¹H NMR (CDCl₃, δ):

Ferrocenyl-1H-indol-2-yl-(2-methoxyferrocenyl)phosphinate

(54). Compound 47 (100 mg, 0.177 mmol), diisopropylamine (0.15

mL, 1.06 mmol), BuLi (0.43 mL, 1.08 mmol), and dimethyl sulfate

(0.10 mL, 1.06 mmol) were reacted at 0 °C for 4 h according to the

general procedure described above. Puriﬁcation was realized by

column chromatography (silica, column size 2.5 × 12 cm) using a

85:15 dichloromethane/ethyl acetate mixture (v/v) as the eluent.

Compound 54 was obtained as a mixture of both diastereomers in a

ratio of 1:0.098 (de = 0.82). Yield: 69 mg (0.119 mmol, 67% based on

47). Anal. Calcd for C₂₉H₂₆Fe₂NO₃P (579.19 g/mol): C, 60.14; H,

3.35 (s, 3 H, OCH₃, ma), 3.59 (ddd, J_H,H= 2.7 Hz, J_H,P= 2.7 Hz, J_H,H

1.5 Hz, 0.3 H, C₅H₃, mi), 3.73 (ddd, J_H,H= 2.6 Hz, J_H,P= 2.6 Hz, J_H,H

1.4 Hz, 0.3 H, C₅H₄, mi), 3.76 (ddd, J_H,H= 2.7 Hz, J_H,P= 2.7 Hz, J_H,H

=

1

4.52; N, 2.42. Found: C. 59.61; H, 4.30; N, 2.60. Mp: ∼25 °C. H

NMR (CDCl₃, δ): 3.73−3.75 (m, 2 H, C₅H₄), 3.82 (s, 3 H, OCH₃),

3.89 (s, 0.3 H, OCH₃, mi), 3.98 (s, 5 H, C₅H₅), 4.14−4.16 (m, 6 H,

C₅H₅, C₅H₃), 4.18−4.20 (m, 1 H, C₅H₄), 4.23 (s, 0.5 H, C₅H₅, mi),

4.24−4.26 (m, 1 H, C₅H₄), 4.32 (ddd, J_H,H= 2.6 Hz, J_H,P= 2.6 Hz, J_H,H

1.5 Hz, 1 H, C₅H₄, ma), 3.77−3−78 (m, 0.3 H, C₅H₄, mi), 3.79 (ddd,

J_H,H= 2.6 Hz, J_H,P= 2.6 Hz, J_H,H= 1.5 Hz, 1 H, C₅H₄, ma), 3.83 (s, 0.9

H, OCH₃, mi), 3.89 (dpt, J_H,P= 2.8 Hz, ^3,4J_H,H= 2.8 Hz, 0.3 H, C₅H₃,

mi), 4.10−4.11 (m, 6 H, C₅H₅, C₅H₃, ma), 4.13 (s, 1.5 H, C₅H₅, mi),

4.15 (ddd, J_H,P= 3.5 Hz, J_H,H= 2.7 Hz, J_H,H= 1.5 Hz, 1 H, C₅H₃, ma),

4.19−4.20 (m, 0.3 H, C₅H₄, mi), 4.21−4.22 (m, 1 H, C₅H₄, ma), 4.27

(s, 1.5 H, C₅H₅, mi), 4.28 (ddd, J_H,H= 2.8 Hz, J_H,P= 2.8 Hz, J_H,H= 1.4

Hz, 0.3 H, C₅H₃, mi), 4.41−4.42 (m, 1 H, C₅H₄, ma), 4.44 (s, 5 H,

C₅H₅, ma), 4.51−4.53 (m, 0.3 H, C₅H₄, mi), 4.54 (ddd, J_H,H= 2.8 Hz,

J_H,P= 2.8 Hz, J_H,H= 1.4 Hz, 1 H, C₅H₃, ma), 7.29 (ddd, J_H,H= 7.9 Hz,

= 1.5 Hz, 1 H, C₅H₃), 4.43 (s, 0.5 H, C₅H₅, minor), 4.57 (ddd, J_H,H

=

2.6 Hz, J_H,P= 2.6 Hz, J_H,H= 1.5 Hz, 1 H, C₅H₃), 7.17 (ddd, ³J_H,H= 8.0

Hz, J_H,H= 7.0 Hz, J_H,H= 0.9 Hz, 1 H, H5/6), 7.32 (ddt, ³J_H,H= 8.1 Hz,

3

J_H,H= 7.1 Hz, J_H,H= 0.8 Hz, 1 H, H5/6), 7.36 (ddd, J_H,P= 4.3 Hz,

J_H,H= 1.9 Hz, J_H,H= 0.8 Hz, 1 H, H3), 7.50 (dd, ³J_H,H= 8.3 Hz, J_H,H

0.7 Hz, 1 H, H7), 7.75 (dd, J_H,H= 8.0 Hz, J_H,H= 0.5 Hz, 1 H, H4),

=

3

T

DOI: 10.1021/acs.joc.7b00030

J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

Article

9.59 (s, 1 H, NH). ¹³C{¹H} NMR (CDCl₃, δ): 56.4 (d, J_C,P= 9.7 Hz,

mL, 43.83 mmol) were reacted according to the general procedure

1

C₅H₃), 58.5 (OCH₃), 59.9 (d, J_C,P= 167.6 Hz, C_C5H3−P), 60.03

described above. The title compound 2o was obtained as a colorless

1

(C₅H₄), 60.06 (C₅H₄), 60.08 (C₅H₄), 60.12 (C₅H₄), 62.56 (C₅H₄),

62.57 (C₅H₄), 64.4 (d, J_C,P= 12.1 Hz, C₅H₃), 67.8 (d, J_C,P= 11.1 Hz,

C₅H₃), 69.5 (C₅H₅), 70.1 (C₅H₅), 111.7 (d, ⁴J_C,P= 1.5 Hz, C7), 112.4

oil. Yield: 2.35 g (8.27 mmol, 58% based on carbazole). H NMR

3

(CDCl₃, δ): 7.45 (td, J_H,H= 8.0 Hz, J_H,P= 0.8 Hz, 2 H), 7.53 (dd,

³J_H,H= 8.5 Hz, J_H,H= 7.4 Hz, J_H,P= 1.3 Hz, 2 H), 8.03−8.05 (m, 2 H),

2

3

8.16 (d, J_H,H= 8.4 Hz, 2 H). ³¹P{¹H} NMR (CDCl₃, δ): 0.5.

(d, J_C,P= 16.1 Hz, C3), 117.3 (d, J_C,P= 6.6 Hz, C_C5H4−O), 120.5

2

(C5/6), 122.3 (C4), 124.6 (C5/6), 127.0 (d, J_C,P= 10.2 Hz, C_C5H3

−

Crystallographic data of 4, 6, 9, 10, 13, 16a, 22b, 24, 26b, 27a, 28b,

31, 34, 40, 47, 48, and 51−53 are also available from the Cambridge

Crystallographic Database as ﬁle numbers: CCDC 1474110 (4),

1508129 (6), 1474107 (9), 1474108 (10), 1474109 (13), 1474111

(16a), 1474112 (22b), 1508130 (24), 1508131 (26b), 1508132

(27a), 1508133 (28a·CHCl₃), 1508134 (31), 1508135 (34), 1508136

(40), 1525260 (41), 1508137 (47), 1508138 (48), 1508139 (51·0.9

CH₂Cl₂), 1508140 (52), 1508141 (53·CHCl₃).

3

1

O), 127.3 (d, J_C,P= 10.2 Hz, C3a), 128.9 (d, J_C,P= 172.2 Hz, C_C2−

P), 137.9 (d, J_C,P= 11.0 Hz, C7a). ³¹P{¹H} NMR (CDCl₃, δ): 25.3

3

(minor), 25.9 (major). HRMS (ESI-TOF) m/z: [M]⁺calcd for

C₂₉H₂₆Fe₂NO₃P 579.0344; found 579.0370.

Synthesis of Chloro Phosphates: General Procedure. The

respective alcohols were dissolved in 10 mL of tetrahydrofuran

followed by the addition of an equal volume of diethyl ether. The

mixture was cooled to −30 °C, and BuLi (2 equiv) was added

dropwise, resulting in the formation of a colorless precipitate. After the

mixture was stirred for an additional 10 min at −30 °C, POCl₃(1

equiv) was slowly added and the solution was warmed to ambient

temperature and stirred overnight. All volatiles were removed under

reduced pressure. The resulting residue was suspended in diethyl ether

and ﬁltered through a plug of Celite (minimum 5 cm) with diethyl

ether to remove the lithium salt. After removal of all volatiles, the

respective chlorophosphates 2a−o were obtained as colorless oils or

solids and were used without further puriﬁcation, as long as solely one

signal in the ³¹P{¹H} NMR was present.

ASSOCIATED CONTENT

* Supporting Information

The Supporting Information is available free of charge on the

ACS Publications website at DOI: 10.1021/acs.joc.7b00030.

■

S

X-ray data for 4, 6, 9, 10, 13, 16a, 22b, 24, 26b, 27a, 28b,

31, 34, 40, 47, 48, and 51−53 (CIF)

Additional details, Tables S1−S7, and Figures S1−S33

(PDF)

Dichloro(pyridine-3-yl)phosphate (2f). 3-Hydroxypyridine (2.50 g,

26.3 mmol), BuLi (10.5 mL, 26.3 mmol), and POCl₃(2a, 7,2 mL,

78.86 mmol) were reacted in tetrahydrofuran according to the general

procedure, described above. The title compound was obtained as a

colorless solid. Yield: 3.12 g (14.7 mmol, 56% based on 3-

AUTHOR INFORMATION

Corresponding Author

*E-mail: heinrich.lang@chemie.tu-chemnitz.de.

ORCID

Heinrich Lang: 0000-0001-9744-7906

Notes

The authors declare no competing ﬁnancial interest.

■

1

hydroxypyridine). H NMR (CDCl₃, δ): 7.43−7.50 (m, 1 H), 7.72−

7.78 (m, 1 H), 8.61−8.72 (m, 2 H). ¹³C{¹H} NMR (CDCl₃, δ): 127.8,

3

135.4 (d, J_C,P= 5.0 Hz), 136.6 (d, J_C,P= 7.1 Hz), 141.9, 147.9 (d,,

²J_C,P= 10.2 Hz). ³¹P{¹H} NMR (CDCl₃, δ): 4.5.

(11bR)-4-Chlorodinaphtho[2,1-d:1′,2′-f ][1,3,2]dioxaphosphepine

4-oxide (2g). 1,1′-(R)-Binaphthol (2.00 g, 7.0 mmol), BuLi (2.8 mL,

6.25 mmol), and POCl₃(1.9 mL, 20.7 mmol) were reacted in diethyl

ether according to the general procedure, described above. The title

compound was obtained as a colorless solid. The spectroscopic data

are in agreement with those reported in literature.⁸²Yield: 1.68 g (4.6

mmol, 65% based on 1,1-(R)-binaphthol). ¹H NMR (CDCl₃, δ):

7.04−7.07 (m, 2 H), 7.13−7.30 (m, 4 H), 7.39−7.52 (m, 2 H), 7.77−

7.78 (m, 1 H), 7.84−7.89 (m, 2 H), 7.94−7.98 (m, 1 H). ³¹P{¹H}

NMR (CDCl₃, δ): 10.9.

ACKNOWLEDGMENTS

M.K. thanks the Fonds der Chemischen Industrie for a Ph.D.

Chemiefonds fellowship.

■

DEDICATION

■

Dedicated to Prof. Gottfried Huttner on the occasion of his

80th birthday.

Dichloro(1H-pyrrol-1-yl)phosphonate (2m). In a Schlenk tube,

1H-pyrrole (1 mL, 14.46 mmol) and 30 mL of diethyl ether were

cooled to −30 °C. To the solution BuLi (5.8 mL, 14.5 mmol) was

dropwise added. In a second Schlenk tube, a solution of 50 mL diethyl

ether and POCl₃(2a, 5 mL, 54.8 mmol) was cooled to −80 °C. The

mixture containing lithiated pyrrole was cooled to −80 °C and was

very slowly added to the POCl₃solution by using a transfer cannula.

The workup procedure is similar to the general procedure, described

above. The title compound was obtained as a colorless oil. Yield: 968

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3

4

(CDCl₃, δ): 6.80 (dd, J_H,H= 3.5 Hz, J_H,P= 3.5 Hz, 1 H, H3), 7.35

3

4

3

(td, J_H,H= 7.3 Hz, J_H,H= 0.8 Hz, 1 H, H5/6), 7.40 (td, J_H,H= 7.3

4

3

Hz, J_H,H= 0.8 Hz, 1 H, H5/6), 7.49 (dd, J_H,H= 3.5 Hz, J_H,P= 3.5

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C4/8). ³¹P{¹H} NMR (CDCl₃, δ): 2.7.

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(2.393 g, 14.31 mmol), BuLi (5.8 mL, 14.5 mmol), and POCl₃(4

U

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Reactivity of Ferrocenyl Phosphates Bearing (Hetero-)Aromatics and [3]Ferrocenophanes toward Anionic Phospho-Fries Rearrangements

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