(Planar-Chiral) Ferrocenylmethanols: From Anionic Homo Phospho-Fries Rearrangements to α-Ferrocenyl Carbenium Ions

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Title: (Planar-Chiral) Ferrocenylmethanols: From Anionic Homo

Phospho-Fries Rearrangements to α-Ferrocenyl Carbenium Ions

Authors: Marcus Korb, Julia Mahrholdt, and Heinrich Lang

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To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.201700645

Link to VoR: http://dx.doi.org/10.1002/ejic.201700645

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European Journal of Inorganic Chemistry

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(Planar-Chiral) Ferrocenylmethanols: From Anionic Homo

Phospho-Fries Rearrangements to α-Ferrocenyl Carbenium Ions

Marcus Korb,^[a]Julia Mahrholdt,^[a]Heinrich Lang*^[a]

Dedicated to Prof. Dr. Dieter Fenske on the occasion of his 75^thbirthday

Abstract: The reaction of FcCH₂OH with chlorophosphates gave

ferrocenyl phosphates FcCH₂OP(O)(OR)₂(Fc = Fe(η⁵-C₅H₅)(η⁴-

C₅H₄)), which readily separate into phosphate anions and ferrocenyl

carbo-cations. The latter species undergoes consecutive reactions, e.

g. electrophilic aromatic substitutions. When nitriles, instead of

alcohols, are treated with FcLi or ^tBuLi and chlorophosphates, chiral-

pool based ferrocenyl imino phosphoramidates Fc-CR=N-P(O)(OR*)₂

are formed, which are promising candidates for anionic homo

phospho-Fries rearrangements. Moreover, the sterically demanding

chiral chlorophosphate with R* enabled oxidative couplings of the

imines to form a diferrocenyl azine. Similarly, the reaction of Fc–Li

with 9-anthrylnitrile produced a 10-ferrocenyl-substituted product,

contrary to a reaction at the C≡N functionality. A planar-chiral ortho-

P(S)Ph₂-functionalized ferrocenylmethanol also gave carbo-cations

under acidic conditions. These species can be sulfurized in a unique

way giving thio ethers, whereby the in situ formed 1,2-P(S)Ph₂,CH₂⁺

ferrocene cation acts as the sulfur and electron source. However,

lowering the substrate concentration prevents sulfur migration,

resulting in electrophilic substitution reactions with aromatic solvents.

Planar-chiral ferrocenylmethyl thio or anisyl derivatives were applied

as ligands in Pd-catalyzed Suzuki-Miyaura C,C cross-coupling for the

atropselective synthesis of hindered biaryls with up to 26 % ee at low

catalyst loadings (1 mol-% Pd).

ferrocenyl phosphines bearing ortho-donor atoms or groups, e. g.

oxygen^2,3, aryl⁴or vinyl,^5,6have been shown to increase the

catalytic activity. The vinyl fragment thereby acts as a hemi-labile

group, which enables the planar-chirality of the ferrocenyl

backbone to be transferred on a substrate, resulting in the

formation of biaryls in an enantiomeric excess of up to 36 %.⁵It

could be shown that the presence of an oxygen atom attached to

the ferrocenyl backbone enhances the catalytic activity, as

characteristic for a 2-alkyloxy substituted phosphine.^2,3However,

a chiral 1,2-P,O-substitution pattern is difficult to achieve, due to

a

lack of oxygen electrophiles, when starting with chiral

phosphines.^1,3In contrast, a stereopure ortho-lithiation and

functionalization with phosphorus electrophiles requires chiral,

oxygen-functionalized ortho-directing groups. Since the ether

motif is a rather weak ortho-directing group, predominantly 1,1’-

functionalized products were obtained.^2,7,8To investigate, if the

planar-chiral ferrocenyl backbone can transfer its chirality to a C,C

coupling product, the presence of a further chiral group (P- or C-

chiral) should be avoided. Thus, we recently applied the anionic

phospho-Fries rearrangement on ferrocenes.³This intramolecular

1,3-OC migration regioselectively gave access to a broad range

of 1,2-P,O-substituted ferrocenes.³Using chiral pool alcohols

allowed a diastereomeric proceeding with a de of the products

exceeding 96 %.⁹The conversion of the formed phosphonate to

the final phosphine also proceeded enantioselectively (99 % ee).

Nevertheless, the use of this 1-PPh₂-2-OMe ferrocene as a ligand

for C,C cross-coupling catalysis did not result in a detectable ee

in the formed biaryls, due to the geometry of the ferrocenyl C₅H₃

ring and the low steric demand of the hemilabile methoxy group.

Replacement of the methyl by an aryl group could therefore

enhance the chirality transfer within the C,C cross-coupling

protocol, due to steric reasons and attractive dispersion

interactions.^{4, 10 , 11}Attempts to adopt this strategy on 1,2-P,O

ferrocenes were successful by applying nucleophilic aromatic

substitution reactions by using electron deficient arenes.^12,13P,C

bond-cleavage prevented the successful formation of the

respective aryloxy ferrocenylphosphines.

Introduction

Ferrocenylphosphines

and

1,2-disubtituted

planar-chiral

ferrocenes are, for example, essential in the field of catalysis.¹

Especially the synthesis of hindered biaryls by the Pd-catalyzed

C,C cross-coupling reaction is still a challenging task, where

[a]

Marcus Korb, Julia Marholdt, Prof. Dr. Heinrich Lang

Technische Universität Chemnitz, Faculty of Natural Sciences,

Institute of Chemistry, Inorganic Chemistry, D-09107 Chemnitz,

Germany

E-mail: heinrich-lang@chemie.tu-chemnitz.de

In addition, 1-PPh₂-2-CH₂OR ferrocenes, where an additional

methylene group is present between the ferrocenyl backbone and

the oxygen donor atom, were prepared.^11,14The usage of this type

of sandwich compounds as ligands within Suzuki-Miyaura C,C

cross-coupling reactions gave the respective biaryls with an ee of

up to 37 %, most likely due to the planar as well as the C-central

Supporting information for this article is given via a link at the end of

the document. Text, Tables SI1–9, Figures SI1–19, and CIF files

giving additional experimental and crystallographic data as well as

spectroscopic details for all new compounds. This material is

available free of charge via the Internet at http://pubs.acs.org .

Crystallographic data are also available from the Cambridge

Crystallographic Database as file numbers: CCDC 1525943 (1g),

1525944 (8), 1525945 (11b), 1525946 (14), 1525947 (18b),

1525948 (18c ∙ EtOH), 1525949 (19), 1525950 (20), 1525951 (22),

1525952 (32), 1525953 (33), 1525954 (34a), 1525955 (37),

1525956 (40a ∙ CH₂Cl₂).

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chirality. The angle between the P- and O-donor atoms also

seems to play a decisive role (Figure 1).

Scheme 1. Retrosynthesis for the preparation of 1,2-substituted ferrocenes by using the

anionic homo phospho-Fries rearrangement.

Results and Discussion

Anionic homo phospho-Fries rearrangement

As shown in Scheme 1, the simplest educts for anionic homo

phospho-Fries rearrangements (ahpFr) are ferrocenyl methanols

(Scheme 2). The usage of BuLi ensured complete deprotonation

of alcohols 1a–c.⁹Chiral-pool-derived chlorophosphate 2a,

bearing two (1R)-α-fenchyl (= Fn) groups showed the best results

for a diastereoselective proceeding of the lithiation and 1,3-OC

migration, as compared to other alcohols, e.g. menthol, borneol

and isopinocampheol, respectively.⁹Thus, 2a was used as the

electrophile for phosphate formations reported herein. Upon

treatment of 1a–c–Li with 2a the formation of phosphates 3a–c

was, however, not observed (Scheme 2). Instead, for 1a-Li, the

main product was identified as the respective ether 6a (46 %

yield), besides 12 % of the starting material 1a, 3 % of methyl

ferrocene (7) and 6 % of the fenchyl ether 8 (Scheme 2). The

formation of 6a indicates that 3a has been formed in situ, which

consecutively was attacked by further 1a–Li to give 6a. This

Figure 1. Comparison between 5- (type A⁹and B¹⁵molecules) and 6-

membered (type C¹⁴and D¹⁶molecules) 1,2-substituted phosphine Pd

complexes and the resulting ee of formed biaryls within Suzuki-Miyaura C,C

cross-coupling reactions. a) The vinyl group is η²-coordinated to Pd, which in

turn is rotated by 52 ° out of coplanarity.¹⁶

Whereas a 1,2-P,O substitution pattern at ferrocene gave a 5-

membered Pd complex (type A³and B¹⁵molecules, Figure 1), the

introduction of a methylene linking unit increases the size to a 6-

membered cycle (C and D^5,6,16, Figure 1).¹⁷Increasing the steric

demand of R from ethyl to (1R)-menthyl in the type C species,

also enhanced the ee from 0 to 37 % (Figure 1).¹⁴The study also

showed that the increased ee is accompanied with a loss of

activity.¹⁴The ee of 36 % for aromatic substituents can be

nucleophilic attack is favored by the elimination of 5a as a leaving

22

group besides the formation of 4⁺.

The generation of

ferrocenylmethyl cations 4a–c⁺is supported by an intramolecular

Fe∙∙∙C⁺interaction.^23,24Thus, 4⁺might be a key intermediate.

The identity of 8 has inter alia been verified by applying single

crystal X-ray diffraction analysis (Figure 2), revealing retention of

the absolute configuration of the fenchyl group as (1R)/endo. The

presence of one set of signals in the ¹H and ¹³C{¹H} NMR spectra

of 8 confirmed the formation of solely one isomer (Experimental

Section). Thus, an addition of a fenchylate at 3a/4a⁺seems to be

convincing, since the reaction of 1a-Li at an OFn functionality

would have resulted in the formation of the exo-derivative.

explained by, e.g. attractive π-interactions.

Besides numerous protocols for the stereoselective introduction

of ortho-substituents,¹a procedure using cheap and easily

available chiral-pool derivatives is pending. Thus, it seems

convincible to apply the anionic homo phospho-Fries

rearrangement on ferrocenes. Based on our recent results on

diastereoselective anionic phospho-Fries rearrangements, the

use of a chiral pool derived phosphate seems promising (type E

18

molecule, Scheme 1). Oximes

(F) and imino-

phosphoramidates ^{19 , 20 , 21}(G) could be used as linkers to the

migrating phosphorus group. Furthermore, these structural motifs

could be functionalized in a straightforward manner after a

successful anionic phospho-Fries rearrangement, allowing the

introduction of further substituents for optimizing the ligand

system.

For methyl-substituted ferrocenyl methanols 1b,c, formal

dehydration occurred and ferrocenes 9a,b were formed (Scheme

2). Thus, the elimination reaction of 3b,c and the subsequent

removal of H⁺was faster than a nucleophilic attack, probably due

to the increased steric demand of the methyl groups. The in situ

formed phosphates 3b–c either underwent an intramolecular

dehydrophosphorylation via

a 6-membered transition state

involving the P=O bond, or an intramolecular C–O bond cleavage.

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Scheme 2. Reaction of ferrocenyl methanols 1a–c with chlorophosphate 2a. (i) THF, –50 °C, ⁿBuLi, 2a, ambient temperature, 18 h. Yields are based on 1a–c. a)

1a as the starting material. b) 1b as the starting material, c) 1c as the starting material. d) Hexane/THF mixture (1:1 ratio, v/v), 60 °C, 18 h. e) Hexane, 60 °C, 1 h.)

To prevent β-H eliminations as observed for 1b and 1c, the alkyl

chains were replaced by phenyl groups as characteristic for 1d,e

(Scheme 3). Lithiation of 1d with BuLi and subsequent treatment

of 1d-Li with 2a gave the respective ether 6b (de = 0.52), whereas

for 1e the starting material could solely be recovered. Compound

6b was obtained in a yield of 87 %.²⁵Since it is not clear if 1e-Li

did react with 2a or was protonated during the work-up procedure,

the steric demand was reduced from fenchyl units in 2a to ethyl

groups in 2b (Scheme 3). The addition of 2b to 1e-Li immediately

resulted in an exothermic reaction. Column chromatic work-up

gave 6,6-diphenylfulvene (10) in 25

%

yield and the

ferrocenylmethyl-substituted cyclopentadienes 11a,b (22 %,

Scheme 3). Similar to the mechanism depicted in Scheme 2, the

in situ formed ferrocenyl phosphate eliminates diethyl phosphate,

leading to the cationic species 4d⁺. This cation underwent an

electrophilic aromatic substitution reaction with a hitherto non-

substituted cyclopentadienyl group, resulting in the release of a

Fe∙∙∙Cp’⁺fragment, which most likely decomposes to 10 and a

Fe²⁺ion. Compound 11 was obtained as a 3:8 cyclopentadiene

isomeric mixture of 11a/11b (Scheme 3), whereas 11b

crystallized from this mixture (Figure 2). After 4 weeks in solution

at ambient temperature, this ratio had changed to 7:4, due to a

1,5-sigmatropic rearrangement, confirming 3-substituted 11a as

the thermodynamically stable product, which is typical for this kind

of molecules.²⁶A rapid 1,5-sigmatropic shift in 11a of the 1H-atom

from the 3- to the 4-position, also gives 11a. However, this

equilibrium results in a broadening of the signals of the C₅H₅and

both C₅H₄signals in the ¹³C{¹H} NMR spectra (ESI).

Scheme 3. Reaction of ferrocenylphenyl methanols 1d,e with chlorophosphates

2a,b. (i) THF, ⁿBuLi, –50 °C, 2a/2b, ambient temperature, 18 h. Yields are based

on 1d,e. a) THF/hexane mixture (1:1, v/v), 60 °C, 18 h.)

The CH₂moiety in 1a was replaced by a CH(^tBu) fragment in 1f

(Scheme 4) to prevent either the ether formation, by an increased

steric demand, or the dehydration reaction, due to the absence of

β-hydrogen atoms. Ferrocenyl methanols 1f,g were accessible by

the reduction of pivaloylferrocene 12f, or the reaction of

acylferrocenes 12a,b with BuLi. Since 12f did not react with

NaBH₄at 60 °C, formyl- (12a, R = H) and acetylferrocene (12b, R

= CH₃) were reacted with ^tBuLi and 2a was subsequently added.

In case of R = H, alcohol 1f was obtained within the appropriate

work-up, which is supported by the absence of the Wagner-

Meerwein rearrangement product 9d. In contrast, for α-ferrocenyl

methanol 1g (R = CH₃), possessing a β-hydrogen atom, the

elimination reaction involving a 6-membered cycle (Scheme 2) or

the formation of 4f⁺occurred, due to the stability of alkyl 4⁺-type

systems and the formation of 9c.²⁷

t

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t

Scheme 4. Reaction of Bu-substituted ferrocenyl methanols 1f,g with chloro-

phosphate 2a. (i) Et₂O, ^tBuLi. ii) Et₂O, ^tBuli, 2a.)

The alkene formation in 9c was prevented by introducing bicyclic

systems such as 2-adamantyl and fenchyl (Scheme 5).

Compound 14 was available by reacting mono-lithiated ferrocene

13–Li²⁸with 2-adamantanone, resulting in the recovery of alcohol

14 in good yields (73 %). An interesting feature in the crystal

structures of 14 (Figure 3) is the presence of a Fe∙∙∙H–O

interaction, due to the orientation of the hydroxy group towards

the Fe atom, also found for 1g (Figure 3). By reacting 13–Li with

the chiral-pool derived ketone (1R)-fenchone, alcohols 15a,b

Figure 2. ORTEP (30 % probability level) of the molecular structures of 8 (left)

and 11b (right) with the atom numbering schemes. All hydrogen atoms and a

second crystallographically independent molecule of the asymmetric unit of 11b

have been omitted for clarity. Selected bond distances (Å), angles (°) and

torsion angles (°) for 8: C11–O1 1.440(8), O1–C12 1.410(8); C1–C11–O1

106.7(6), C11–O1–C12 115.1(5), C5–C1–C11–O1 72.0(8); for 11b: C12–C13

1.446(5), C13–C14 1.446(6), C14–C15 1.439(6), C15–C16 1.445(5), C16–C12

1.362(5), C2–C1–C11–C23 9.7(4); C5–C1–C11–C12 61.0 (4).

29 , 30

were formed as diasteromers (Scheme 5).

A reported

synthetic methodology for 15 is the reaction of (1R)-fenchone with

ferrocene in presence of CeCl₃, giving an epimeric ratio of

1:0.25.²⁹With the herein reported synthetic protocol the epimeric

ratio could be improved to 1:0.13 (Scheme 5). Within the

synthesis of 15, also the ferrocenyl-substituted non-bicyclic side

product 15d was formed (Figure SI2), which can be explained by

a cationic isomerization reaction after release of a diethyl

phosphate anion. Compound 15d could be converted into the

dinitrophenyl hydrazone derivative, verifying the presence of the

keto functionality, which was further evidenced by the appearance

of a resonance signal at 210.4 ppm in the ¹³C{¹H} NMR spectrum

(ESI).

For the deprotonation of 14, BuLi and sodium hydride were used

as bases to investigate the effect of the counter cation towards

the nucleophilic attack at the chlorophosphate 2a. Treatment of

14-Li/Na with 2a in DMF or N-methyl-2-pyrrolidone at 90 °C,

however, exclusively gave the starting material back. The same

result was obtained, when 15 was consecutively treated with BuLi

followed by the addition of 2a (hexane, 80 °C, 18 h). Replacing 2a

by the sterically less demanding diethyl derivative 2b, did not

result in the formation of the corresponding phosphate, rather 15c

could be isolated as a single isomer (Scheme 5). The molecular

structure of 15c is based on NMR spectroscopic (Figure SI3) and

mass-spectrometric studies (m/z = 336.1163 for C₂₀H₂₄FeO). The

formation of 15c indicates a cationic isomerization reaction after

release of diethyl phosphate, as characteristic for 11a,b (Scheme

3).

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O1∙∙∙Fe1 3.575(2), O1–H1∙∙∙Fe1 117.94, C2–C1–C11–C13, 85.0(4); C2–C1–

C11–O1 31.7(4).

Another structural motif, suitable for a phosphate formation, are

31

oximes.

To prove, if this synthetic methodology is also

applicable for ferrocene-based oximes, 16a,b were prepared

(Scheme 6). Hence, acylferrocenes 12a–d were reacted with

32

hydroxylammonium chloride in the presence of NEt₃.

Nevertheless, only formylferrocene (12a) could be converted to

oxime 16a (82 % yield), while 12b–d inhibited the formation of

16c,d, which most likely is attributed to the increased electron

density of 12b–d. In case of 12b, a 1:1 mixture of the starting

material with the oxime 16b was isolated after appropriate column

chromatographic work-up. Compound 16c has not yet been

reported in literature, most probably, due to its rapid hydrolysis to

33

give 12d. We assume that 16d

and partially 16b were

hydrolyzed during the column chromatographic workup.

t

Deprotonation of 16a was achieved using BuLi as a sterically

demanding, non-nucleophilic base to avoid a nucleophilic attack

at the carbonyl carbon atom. Subsequent treatment of 16a–Li with

2a predominantly resulted in the formation of ferrocenylnitrile 17

in 72 % yield, along with 12a (8 %) and 1f (3 %). While phenyl

oximes can successfully be converted into their respective

phosphates,³¹ferrocenyl-based derivatives seem to undergo

similar dehydration reactions as compared to the ferrocenyl

methanols 1b,c,e in the presence of 2a (vide supra).

Recently electron-poor pyrrolyl-, indolyl- and carbazolyl-

containing phosphoramidates were converted into stable

ferrocenyl phosphoramidates. ³⁴Thus, the CR₂–O motif was

Scheme 5. Synthesis of ferrocenyl alcohols 14 and 15a,b and their subsequent

reaction with chlorophosphates 2a/2b in the presence of a base. (i) ^tBuLi, THF,

KO^tBu, –80 °C, 2-adamantanone (14)/ (1R)-fenchone (15). Yields are based on

13. ii) BuLi, Et₂O, –30 °C, ClP(O)(OEt)₂(2b). Yields are based on 15.)

replaced by a CR=N-bonded ferrocenyl unit.

This imino

phosphate motif (type G molecule, Scheme 1) has rarely been

described, especially in ferrocene chemistry, where a sole C=N–

P(O)Ph₂unit has been reported, however, without its synthetic

The results derived by the reaction of ferrocenyl methanols 1a–g,

14 and 15a,b with either the difenchyl (2a) or the diethyl

chlorophosphate (2b) indicate that they are rather unsuited

starting

materials

for

anionic

homo

phospho-Fries

rearrangements, due to their rapid decomposition and elimination

reaction of the in situ formed phosphates.

procedure.^35,36

Scheme 6. Conversion of 12a–d to ferrocenyl oximes 16a,b and their reaction

behavior towards chlorophosphate 2a. Yields of 16a,b are based on 12a,b.

The imino phosphato motif could, e.g. be obtained by

condensation reactions of carbonyl derivatives with NH₂-bearing

phosphoramidates.^20,37,38A protocol using oximes, tosylazide or

chlorophosphates also allows the preparation of imino

Figure 3. ORTEP (50 % probability level) of the molecular structures of 14 (left)

and 1g (right) with their atom numbering schemes. C-bonded hydrogen atoms

39

phosphates.

In addition, the reaction of organolithium

compounds with nitriles could be applied in the synthesis of imino

phosphates,⁴⁰however, the alkyl-substituted imino phosphates

and

a second crystallographically independent molecule, present in the

asymmetric unit of 14, have been omitted for clarity. Selected bond distances

(Å), angles (°) and torsion angles (°) for 14: C11–O1 1.451(5), C11–O1 1.440(3),

O∙∙∙Fe 3.370(3)/3.372(2), O–H∙∙∙Fe 128.6/130.8, C–C1–C11–O1 48.0(4); for 1g:

rapidly

isomerize

into

the

respective

enamine

phosphoramidates.³⁸The latter approach was applied on

t

ferrocenylnitrile 17, which was reacted with MeLi and BuLi to

afford imine anions. In addition, commercially available nitriles

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owere treated with mono-lithio ferrocene 13-Li (Scheme 7). In

both cases, the in situ formed imine anions were subsequently

reacted with 2a giving imino phosphates 18–d in up to 60 % yield

(R = Me, Scheme 7). The E-/Z-ratios for sterically non-demanding

methyl (18a), phenyl (18b) and triphenylphenyl (18c) groups are

similar and ranges between 14.3:1 and 9.1:1 (Experimental

Section). The sterically demanding ^tBu derivative 18d inverted the

E-/Z- ratio to 1:3.85 (Scheme 7). The assignment of the E-

configuration at the C=N double bond for 18b,c is derived from

single crystal X-ray diffraction analysis (Figures 4 and SI7) and is

in accordance with 18a. Within the reaction of ^tBuC≡N with 13–Li

t

Figure 4. ORTEP (30 % probability level) of the molecular structure of 18b with

the atom numbering scheme. Hydrogen atoms have been omitted for clarity.

Selected bond distances (Å): C11=N1 1.286(4), N1–P1 1.645(3), P1–O1

1.569(2), P1–O2 1.583(3), P1–O3 1.457(2).

or 17 with BuLi the formation of oxidative coupled azine 19 is

observed, possessing a Z-/Z-configuration as evidenced by single

crystal X-ray diffraction analysis (Figure 5). Azines are in general

available by reacting carbonyl compounds with hydrazine, ^41,42or

oxidation of hydrazines with oxygen.^41,42They are also accessible

under oxidative conditions by reacting nitriles with RLi and

subsequent treatment with CuCl/O₂,⁴²or in the presence of

perbenzoates.⁴³In contrast, 19 is the first example, which has not

been formed by a condensation reaction with hydrazines.⁴⁴

The use of isopropyl nitrile, as a CH acidic compound, did not

produce the respective phosphate, rather giving ferrocene

(Scheme 7). The 1-adamantyl derivative 18f was not accessible,

due to its steric demand. The reaction of 9-anthryl nitrile with 13–

Li and 2a afforded, instead of the expected phosphate 18g,

compound 22 as a dark red solid. Similar to 19, the formation of

22 can be explained by an oxidative coupling of 13–Li with 9-

anthryl nitrile. However, running the reaction of 9-anthryl nitrile

with 13–Li without chlorophosphate 2a failed to give 22, which is

indicated by the absence of a color change from orange to dark

red. We assume that a nucleophilic attack of 13–Li occurred at

the 10-position of the anthryl backbone, whereby the negative

charge is stabilized by the nitrile substituent and the two attached

aromatic rings. The removal of a hydride could be supported by

chlorophosphate 2a, since chlorophosphates can easily be

reduced with metals (Na, K), potassium naphthalenide ⁴⁵or

NaBH₄.⁴⁶The 9,10-substitution pattern of 22 was inter alia verified

by single crystal X-ray diffraction analysis (Figure 5). The

presence of a C≡N substituent was also evidenced by its ¹³C{¹H}

NMR signal at 118 ppm and the respective stretching ferquency

in the IR spectra at 2208 cm^–1.⁴⁷

The applicability of alkylidene phosphoramidates 18a–d as

starting

materials

for

anionic

homo

phospho-Fries

rearrangements was proven by their treatment with lithium

tetramethylpiperidide (Litmp) or lithium diisopropylamide in either

hexane or THF (Experimental Section). In our recently published

synthetic protocols for the completion of anionic phospho-Fries

rearrangements, ethyl phosphates are preferably lithiated in THF

at low temperature,^3,12whereas steric demanding bicyclic, e.g.

fenchyl groups, require higher temperatures and a non-polar

solvent.^9,13However, the applied reaction conditions described

within our studies herein did not indicate a lithiation of the

ferrocenyl backbone to form 23a–c, whereas molecules derived

from a nucleophilic attack of the base, e.g. 78 % of 12d for 18b,

were detected (Scheme 7).

The reactivity of the C=N bond has exemplarily been investigated

by reacting 18b with acetylacetone in the presence of K₂CO₃. In

contrast to phenyl-based derivatives, where nucleophilic attacks

at the carbonyl atoms proceed^35a,48,49, solely the starting material

was recovered in case of 18b. Reduction of the C=N bond of 18b

by using NaBH₄gave amine 20 (20 % yield) as a 1:0.86:0.23

mixture of three isomers as evidenced by ¹H, ¹³C{¹H} and ³¹P{¹H}

NMR measurements (Experimental Section). Single crystal X-ray

diffraction analysis of 20 (Figure SI11) revealed the crystallization

of a racemic mixture of two epimers with respect to their

configuration at the former carbonyl carbon atom. The reduction

from 18b to 19 could also be confirmed by IR spectroscopic

measurements, where the v_C=Nvibration of the imino

phosphoramidate 18b at 1572 and 1611 cm^–1disappeared, while

a new band at 3185 cm^–1(v_NH) could be observed.

The absence of a phosphoryl moiety in azine 19 was verified by

IR spectroscopy, since the C=N stretching frequency in 18b was

shifted from 1572 and 1611 cm^–1to 1559 cm^–1in 19. The C≡N unit

in 22 absorbed at 2208 cm^–1. A remarkable feature of dark purple

22 is the bathochromic shift and the high absorption coefficient of

1850 L mol^–1cm^–1of the dd transition at 536 nm as compared

to, e.g. 19 (λ_max= 431 nm, ε = 883 L mol^–1cm^–1, Table SI7).

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Scheme 7. Synthesis of imino phosphates 18a–d, azine 19 and anthrylferrocene 22. (i) THF, –80 °C, RLi (R = Me, ^tBu), –30 °C, 2a. Yields are based on 17. ii) THF,

KO^tBu, ^tBuLi, –80 °C, R–C≡N (R = Ph, C₆H₂(Ph)₃, ^tBu, 9-anthryl, iPr, 1-adamantyl), –30 °C, 2a. Yields are based on 2a. iii) THF, NaBH₄, H₂O. Yield based on 18b.

iv) Acetylacetone, K₂CO₃, CH₂Cl₂, MgSO₄, 50 °C 18 h. v) Litmp or LDA, hexane or THF, –40 °C/ 0 °C. a) 78 % of ketone 12d were obtained; Litmp, hexane, tmeda,

25 °C, 48 h without Me₂SO₄).

diferrocenylbutadiene (225 mV).⁵¹If the voltage within the CV

measurement for 18d is increased to > 1300 mV, the redox event

becomes irreversible (Figure SI5), indicating the decomposition of

this oxidized species.

In situ UV-Vis/NIR spectroelectrochemical measurements were

additionally carried out for 19 to prove, if the redox separation of

201 mV is due to an electronic communication between both

ferrocenyls, as observed for 1,4-diferrocenyl butadiene,⁵¹or

caused by electrostatic interactions. However, an inter-valence

charge transfer (IVCT) absorption in the region between 1250 and

Figure 5. ORTEP (50 % probability level) of one of the crystallographically

2750 nm⁵²has not been observed (Figure SI6), revealing that the

independent molecules of the asymmetric unit of 19 (top) and 22 (bottom).

redox separation is due to electrostatic interactions and no

Hydrogen atoms have been omitted for clarity. Selected bond distances (Å),

electronic communication between the Fc and Fc⁺fragments

angles (°) and torsion angles (°) for 19: C=N 1.277(10)–1.293(10), N–N

occurred in the mono-oxidized mixed-valent species. The

1.389(9)/1.385(9), C1–C11–N1, C–N–N 120.2(7)–120.5(7), C–N–N–C

absence of an electronic communication between the both

ferrocenyls in 19 might be supported by the non-planar C=N–N=C

126.9(8)/ 127.6(8); for 22: C25–N1, 1.142(4), C18–C25 1.441(5).

moiety in the solid state structure (Figure 5), due to a torsion angle

The presence of two ferrocenyl units within one molecule,

of ~53 °.

separated by a π-conjugated bridge allows for the investigation of

an electronic communication between the redox centers in the

single-oxidized mixed-valent species. Thus, the electrochemical

Planar-chiral Ferrocenyl Methanols

behavior of the diferrocenyl compound 19 was investigated by

Attempts to apply the anionic homo phospho-Fries rearrangement

cyclic voltammetry (CV) and square-wave voltammetry (SWV)

at ferrocenyl methanols, oximes and imines showed that the

(Figure SI4), and compared with 18d possessing a similar

additional methylene or CR₂fragment, between the ferrocenyl

substitution pattern at the C=N carbon atom (Table SI8).

and hydroxyl group, causes side reactions and prevents a

Compound 19 showed two reversible one electron redox events

successful formation of phosphates. The initial 1,2-P,CH₂OH

at 24 and 225 mV, one was observed for 18d (–135 mV). If the

substitution pattern, well-suitable for further functionalization, was

N=C group in 19 is replaced by the phosphoryl group in 18d, the

synthesized by a known literature eight-step synthetic procedure

first redox event is shifted from 24 (for 19) to –135 mV, ascribing

(Scheme 8).^5,53Thus, formylferrocene⁵⁴was first converted into

the azine motif to be more electron-withdrawing, as compared to

the chiral acetal (4S)-24, followed by diastereoselective lithiation

the phosphoryl group. The redox events in 2,3-diazabutadiene 19

are separated by 201 mV, which is higher than for the literature

ClPPh₂(Scheme 8). After subsequent cleavage of the acetal

known 1,4-diaza derivative (< 100 mV)⁵⁰, but lower than for 1,4-

t

in ortho-position with BuLi and the consecutive reaction with

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group the enantiopure phosphane (S_p)-25 could be obtained.⁵³

Aldehyde (S_p)-25 was reduced to alcohol (S_p)-26 by using NaBH₄,

followed by the addition of sulfur to the reaction mixture to protect

the lone-pair of electrons at the phosphorus atom. The reaction of

(S_p)-27 with ethanol, benzyl alcohol or menthol was recently

reported, whereby the yields of the corresponding ethers reduced

from 56 to 27 % in the same order.¹⁴Attempts to react (S_p)-27

with the sterically more demanding (1R)-α-fenchyl (Fn, Scheme

8) and (1S)-borneyl alcohols (Bo) in presence of p-TsOH afforded

a mixture of non-separable ferrocenyl species rather than (S_p)-

28/29 (Scheme 8).

27 under acidic conditions and a migration of a P-bonded sulfur

to the exo carbon atom, where the positive charge is present

(Scheme 9). This might have occurred via an inter- or

intramolecular mechanism by passing through a 5-membered

transition state (Scheme 9). In contrast to hydroxy, the formed

thiol functionality is not removed acid-catalyzed and reacts with

(S_p)-30⁺forming thioether (S_p,S_p)-32. It should be noted that for

the conversion of ferrocenyl methanol (1a) to the respective thiol

derivative, Lawesson’s reagent is generally required as a sulfur

source.⁵⁵The reaction strongly depends on the concentration of

(S_p)-27 in the reaction mixture and lowers the yield of (S_p,S_p)-32

to 26 %, while changing from 48 mmol L^–1to 96 mmol L^–1(Table

SI1). Interestingly, the higher concentration preferably resulted in

the formation of (S_p,S_p)-31, indicating that the reaction of (S_p)-27

with (S_p)-30⁺is faster as compared to the removal of an OH group

and the migration of the sulfur atom. However, (S_p,S_p)-31 could

not be separated from its mixture with (S_p,S_p)-32, neither by

crystallization nor column chromatography. Suggesting that a

further decrease of the concentration of (S_p,S_p)-32 would improve

the yield, a 28 mM solution was used for the conversion. However,

an electrophilic aromatic substitution of the solvent occurred

(Scheme 10), giving (S_p)-33 in 71 % yield. The reaction of the

carbo-cation (S_p)-30⁺with toluene was suppressed by changing

the solvent to 1,4-dioxane, which increased the yield of (S_p,S_p)-32

to 90 % (Scheme 9, Table SI1).

Scheme 8. Synthesis of (S_p)-27 and its acid catalyzed reaction with chiral-pool

t

alcohols. (i) 1^st, BuLi, Et₂O, –78 °C, ClPPh₂, –30 °C, 99 % de; 2^nd, p-TsOH,

CH₂Cl₂/H₂O, reflux, 74 % based on (4S)-24. ii) NaBH₄, MeOH, 2 h, 25 °C, 92 %

based on (S_p)-25. iii) S₈, 2 h, CH₂Cl₂, 25 °C, 95 % based on (S_p)-26. iv) p-TsOH,

ROH, R = Fn/Bo.)

Ferrocene (S_p)-27 was also reacted with p-TsOH without adding

a further electrophile to force the self-condensation to (S_p)-31

(Scheme 9). However, instead of the oxoether (S_p,S_p)-31, the

thioether (S_p,S_p)-32 was formed in 72 % yield. The replacement

of the oxygen by a sulfur atom was evidenced by a shift of the

adjacent CH₂fragments in the ¹³C{¹H} NMR spectrum from 59.9

ppm (27) to 31.3 ppm (32) (Table SI5). The molecular structure of

32 in the solid state was additionally confirmed by single crystal

X-ray diffraction analysis (Figure 6). The NMR data especially of

the CH₂moiety in (S_p)-27 are in the range for CH₂–O fragments

(Table SI5).¹⁴Elemental analysis further evidenced the formation

of (S_p)-27. Addition of sulfur within the conversion of (S_p)-27 to

(S_p,S_p)-32 remains the yield at 77 %, revealing that inorganic

sulfur is not involved within the formation of 32. Thus, (S_p)-30⁺is

considered as the sulfur source. For the calculation of the herein

reported yields of (S_p,S_p)-32, three molecules of (S_p)-27 must be

considered. Desulfurized 30⁺most likely decomposed releasing

two electrons, which are required for the formation of 32. We

assume that the other reaction components (dioxane or toluene,

p-TsOH and H₂O) are unsuitable as electron donors under these

reaction conditions. The removal of sulfur from (S_p)-27 can be

excluded, since the formed (S_p)-26 can easily be re-oxidized.

According to the above mentioned stability of ferrocenyl methyl

carbenium ions, we assume the removal of the OH group in (S_p)-

Scheme 9. Acid-induced formation of (S_p,S_p)-32. Yields are based on (S_p)-27,

whereas for (S_p,S_p)-32 the requirement of one molecule of (S_p)-27, as the sulfur

source has been taken into consideration. (i): p-TsOH ∙ H₂O (3 equiv), toluene,

80 °C, 18 h. a) 48 mmol L^–1. b) 96 mmol L^–1. c) In 1,4-dioxane.)

Attempts to obtain (S_p,S_p)-31 by a similar reaction, as observed

for 6a (Scheme 2) or 6b (Scheme 3), gave, however, 50 % of the

starting material back and an unidentifiable mixture of compounds.

The lowering of the concentration of (S_p)-27 in the reaction

mixture should not affect the sulfur migration, if an intramolecular

mechanism is considered and thus, the yield of (S_p,S_p)-32 should

not be decreased. Instead, the reaction of 30⁺with toluene was

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observed, instead of

intermolecular process.

a

sulfur migration, indicating an

IR spectroscopy verified the presence of the nitro groups in 37,

which were observed with their NO stretching frequency at 1520

and 1345 cm^–1. As expected,⁶⁴the P=S stretching vibration was

observed, e.g. for 35 and 37 at 643 and 645 cm^–1, respectively. In

phenol 35, the OH band was observed at 3403 cm^–1.

The observed reaction of (S_p)-30⁺with the solvent toluene was

further investigated, since this electrophilic aromatic substitution

reactions are rarely described so far.^24,56Recently, ferrocenyl

methanol (1a) was coupled with electron-rich aromatics, e.g. 2-

naphthol, pyrrole giving 1-naphthylmethyl and 2-pyrrolylmethyl

ferrocenes by using (NH₄)₂[Ce(NO₃)₆].²⁴The use of highly

activated salicylate anions predominantly occurred ortho to the

OH group.⁵⁶The Fc–CH₂-Ar pattern is also accessible by the

alkylation^22,57or acylation of ferrocene,^58,59followed by removal of

the oxygen substituent.

The scope of the electrophilic aromatic substitution reaction has

been extended to planar-chiral derivatives by reacting (S_p)-27 with

further aromatics (Scheme 10). In toluene, compound (S_p)-33 was

formed as a 2:1:6 mixture of the o-:m-:p-isomer. The three

regioisomers could not been separated from each other under a

column chromatographic purification process. Thus, their ratio

within the mixture was calculated from the integrals of the ¹H NMR

spectra. Based on electronic and steric properties of the different

isomers, the para-isomer has predominantly been formed, which

is supported by NMR investigations (ESI) and the solid state

structure of (S_p)-33a (Figure SI15). However, using anisole as the

solvent afforded a 1:1 mixture of the ortho- and para-isomers,

while the meta-isomer was not formed. The increased amount of

ortho-substituted (S_p)-34a, compared to the para-product (S_p)-

34b, is due to an electrostatic attraction of the carbo-cation and

the OMe substituents, superimposing the steric effect. The o-OMe

substitution pattern in (S_p)-34a could inter alia been verified by

single crystal X-ray diffraction analysis (Figure SI17). Using

phenol within the electrophilic aromatic substitution reaction

exclusively gave ortho-substituted (S_p)-35. A nucleophilic attack

of the oxygen functionality at the carbo-cation to an aryl ether has

not been observed under the acidic conditions, as it could be

shown for a nucleophilic process.⁵⁶Recently, we could show that

the nucleophilicity of hydroxy-aryl species, e.g. phenolates and

naphtholates is rather low,^34,60concluding that the electrophilic

aromatic substitution is faster and irreversible. Attempts to force

the nucleophilic attack of the oxygen atom by blocking the

electronically preferred ortho- and para-positions as in mesityl

phenol, resulted in the formation of meta-substituted (S_p)-36

(Scheme 10). The meta-methoxy/hydroxy substitution pattern has

rarely been described and usually has to be forced by reacting the

61

Scheme 10. Electrophilic aromatic substitution of (S_p)-27 with electron-rich

arenes giving (S_p)-33–36 and its nucleophilic aromatic substitution with an aryl

fluoride to produce (S_p)-37. Yields are based on (S_p)-27. (i) p-TsOH, toluene

(33a–c), anisole (34a,b), phenol (35), 80 °C. a) As a 2:1:6 mixture. b) CH₂Cl₂,

50 °C, 72 h. c) K₂CO₃, 2,4-dinitrofluorobenzene, DMF. Yield calculated using

two equiv of (S_p)-27.)

appropriate

lihtio-arene

with

formyl

ferrocene

,

cyanomethylferrocene ⁶²or by applying an S_EAr reaction of

ferrocene with the respective aryl carbonyls.⁶³Ferrocenoles have

also been shown to undergo reactions with aryl fluorides, resulting

in stable ferrocenyl aryl ethers even at ambient temperature by

using Sangers reagent (2,4-dinitrofluorobenzene).¹²Thus, (S_p)-27

was activated with K₂CO₃and reacted with Sangers reagent

(Scheme 10). Instead of the oxo ether, the thio derivative (S_p)-37

was formed, which was inter alia proven by single crystal X-ray

diffraction analysis (Figure 6). Most likely, a S_NAr-type reaction

had occurred followed by elimination of 2,4-dinitrophenolate,

subsequent migration of sulfur from the substrate to the exo-

carbo-cation and attack of the formed thiol/thiolate in a further

S_NAr reaction.

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Scheme 11. Desulfurization of (S_p,S_p)-32, (S_p)-34a and (S_p)-36 using P(NMe₂)₃.

a) Single crystals were obtained by crystallization of (S_p)-40 from

a

dichloromethane solution.

The thio ether group in (S_p,S_p)-32 and (S_p)-37 has up to now solely

been achieved by a nucleophilic attack of thiols or thiophenols⁶⁵

at ferrocenyl methanols. The reduction of the P^Vspecies (S_p,S_p)-

32, (S_p)-34a, and 37 to the appropriate P^IIIphosphines was

performed according to literature reported protocols by refluxing

the phosphine sulfides with P(NMe₂)₃in toluene (Scheme 11).¹⁴

However, in case of (S_p,S_p)-32 no product could be isolated under

the conditions applied (Supporting Information). Optimization of

the reaction conditions (Table SI2) showed that with the higher

boiling solvent chlorobenzene the reaction successfully

proceeded at 130 °C. This allowed the isolation of (S_p)-39 after

appropriate work-up in a yield of 51 %.

Attempts to desulfurize (S_p)-36 did not give the P^IIIspecies

(Scheme 11). Instead, the hydroxy group reacts with P(NMe₂)₃

and partial hydrolysis of the phosporamidate to phosphite (S_p)-40

took place after a flash column chromatographic purification

process. The identity of (S_p)-40 was inter alia verified in the form

of its ammonium phosphite (S_p)-40a by single crystal X-ray

diffraction analysis. Hydrolysis occurred during the crystallization

process (Figure SI19). The occurrence of (S_p)-40 and (S_p)-40a as

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

32 (top) and (S_p)-37 (bottom) with their atom numbering scheme. Hydrogen

atoms and a second molecule in the asymmetric unit of (S_p)-37 have been

omitted for clarity. Selected bond distances (Å) and angles (°) for (S_p,S_p)-32:

P=S 1.952(5), C11–S 1.814(13), C11–S–C11A 103.0(9); for (S_p)-37: P=S

1.954(5)/1.960(5), C11–S2 1.858(17)/(1.833(16), S2–C12 1.757(17)/1.724(19),

N–O 1.210(18)–1.235(19), C11–S2–C12 103.7(8)/104.1(9). Symmetry

operation for generating equivalent atoms (A): –y, –x, –z+1/2.

1

the P(O)H tautomer is evidenced by a J_H,Pcoupling constant of

646 Hz for the PH fragment in the ¹H and ³¹P NMR spectra (Table

SI4).

Suzuki-Miyaura Cross-Coupling Reactions

Compounds (S_p,S_p)-38 and (S_p)-39 were investigated as

stereopure, planar-chiral supporting ligands within Suzuki-

Miyaura C,C cross-coupling reactions for the synthesis of

hindered biaryls, using the reaction conditions as reported in

references 3 and 8. The use of bidendate (S_p,S_p)-38 required an

optimization of the Pd:L ratio and concentration (Table SI3), which

has exemplarily been performed for the synthesis of 41a by using

Pd(dba)₂(dba = dibenzylideneacetone) as the Pd source. Starting

with 1 mol-% of Pd and (S_p,S_p)-38 as a ligand, biaryl 41a was

formed almost quantitatively in an ee of 17 %, which is higher than

for the ethyl and benzyl derivatives.¹⁴While decreasing the

Palladium loading to 0.5 and 0.1 mol-%, respectively, reduced the

ee to 12 % and 7 %, associated with a lowering of the yield to

57 % (Entries 1–3, Table SI3). However, a Pd:L ratio of 1:0.5 did

not give 41a. Contrary, changing to a 1:1.5 Pd/L ratio slightly

increased the ee to 20 %. A further increase of the phosphine

loading prevented the formation of an active catalyst (Entry 6,

Table SI3). The substrate scope was extended using the

conditions in Entry 1 (Table SI3) for (S_p,S_p)-38 and the results

thereof are compared with (S_p)-39 as a P,O-substituted ferrocene

(Figure 7).

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Figure 7. Suzuki-Miyaura C,C cross-coupling reactions for the synthesis of ortho-substituted biaryls 41a–o using(S_p,S_p)-38 and (S_p)-39. Reagents and conditions:

aryl halide (1.0 mmol), boronic acid (1.5 mmol), K₃PO₄∙ H₂O (3.0 mmol), toluene (3 mL), 0.5 mol-% [Pd₂(dba)₃], 1.0 mol-%, (S_p,S_p)-38/ 2.0 mol-% (S_p)-39, 70 °C,

24 h. Reaction times were not minimized. Yields are based on isolated material as an average of two runs, except otherwise noted. a) 100 °C. b) Using dppf as the

ligand. c) The product has been obtained from the respective amine. It was converted into the amide by using PhC(O)Cl and NEt₃at 65 °C for 6 h, due to its rapid

decomposition. d) Yields are obtained from the ¹H NMR data of the crude product. e) 1,4-Dioxane, 100 °C, 48 h.

Comparing the yield and ee of the 2-methoxy naphthyl derivatives

41a–e (Figure 7) reveals a dependency on the substitution pattern

of the boronic acid. While a similar ee was observed for an OMe

(41a) and Me (41b) group, an increase of the steric demand gave

a racemic mixture for the phenyl derivative 41d. In contrast, an

ortho-phenyl substituted aryl halide gave 41f with 21 % ee. The

Suzuki-Miyaura reactions were also carried out by using (S_p)-39

as the ligand, giving similar or slightly higher yields of the

respective biaryls, while a somewhat decrease of the ee was

observed for 41a–f (Figure 7). Therefore, we assume a better

stabilization during the catalytic cycle by the anisyl group.

However, the flexibility of the OMe group and the distance to the

planar chiral backbone is not beneficial. The use of the non-chiral

bis(diphenylphosphino)ferrocene (dppf) as ligand gave 41e with a

similar yield as observed for (S_p,S_p)-38 and (S_p)-39, as a racemic

mixture. Replacement of the OMe by a Me group in biaryls 41g,h

gave opposite results for yield and ee, when compared to 41b,h.

Larger condensed aromatics such as 9-bromoanthracene gave

41i in a yield of 78 %. Substituents, which are able to form

hydrogen-bridge bonds could interact with either the ligand or the

active Pd catalyst. Thus, OH, NMe₂and NH₂functionalities were

investigated for the synthesis of 41j–l (Figure 7). However, the

presence of the hydroxy group gave 41j in only 3 % yield, besides

1,1’-binaphthyl and naphthalene. An interaction of the substrate

molecules with the ligands is assumed, since type 41j biaryls are

known to be formed under similar reaction conditions.⁶⁶Similarly,

41k was formed in 14 % yield, besides the starting halide and 1,1’-

binaphthyl.

In contrast to OH, the presence of a NH₂group did not have a

disadvantageous influence. Due to a reported rapid oxidation of

the formed biaryls⁶⁷, the reaction mixture has directly been treated

with benzoyl chloride, giving 41l in 75 % yield and an ee of 8 %.

However, (S_p,S_p)-38 is unsuitable as a ligand in the Suzuki-

Miyaura reaction, if double ortho-substituted boronic acids are

used, as shown for 41m–o (Figure 7). GC-MS analysis revealed

the presence of the starting halide and the respective hydro

deboronation products. Thus, the transmetalation process seems

to be the decisive step within the catalytic cycle.

Conclusion

The anionic homo phospho-Fries rearrangement was applied on

ferrocenyl methanols for the synthesis of the respective planar-

chiral 1,2-P,CH₂O-functionalized derivatives using phosphates as

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key starting material. Within this reaction the addition of chloro-

phosphates resulted in situ in the formation of phosphates, which

rapidly separate into phosphate and ferrocenyl carbenium ions.

These cations underwent electrophilic reactions resulting in the

formation of symmetric diferrocenylmethyl ethers. Replacement

Instruments: FTIR spectra were recorded between NaCl crystals

or as KBr pellets in transition mode. NMR spectra were recorded

with a Bruker Avance III 500 spectrometer (500.3 MHz for ¹H,

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

chemical shifts in δ (ppm) units downfield from tetramethylsilane

+

1

of the CH₂unit by a CPh₂fragment within the respective

ferrocenyl methanols gave diphenyl fulvene. The formation of this

species results from an electrophilic aromatic substitution reaction

of the CPh₂⁺moiety with the hitherto non-substituted cyclopenta-

dienyl ligand. A similar dehydration was observed for ferrocenyl

oximes in the presence of phosphates giving a nitrile. Instead of

with the solvent as the reference signal (CDCl₃: H at δ = 7.26

ppm and ¹³C{¹H} at δ = 77.00 ppm), by external standards (³¹P{¹H}

relative to 85 % H₃PO₄0.0 ppm and P(OMe)₃139.0 ppm) or by

the ²H solvent lock signal. ⁷⁴For 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 identity of all compounds was

established by ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectroscopy. In

addition, 2D experiments, such as COSY, HSQC and HMBC were

carried out. Ferrocenyl related pseudo-triplets are abbreviated by

pt. The melting points were determined with 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. HPLC measurements were

performed with a Knauer system consisting of a HPLC Pump K-

500 and an UV Detector K-2000 operating at 245 nm equipped

with Chiralcel OD-H or OJ-H columns (4.6 ∙ 250 mml column size).

GC-MS analysis were performed with a GCMS-QP2010 SE

system consisting of a coupled gas chromatograph mass

spectrometer from Shimadzu using electron impact ionization.

t

alcohols, the treatment of nitriles with FcLi or BuLi and sub-

sequent addition of a chlorophosphate produced diverse chiral-

pool-based ferrocenyl imino-phosphoramidates. Besides, the

sterically demanding chlorophosphate enabled oxidative coupling

of the imines to afford diferrocenyl azine. The reaction of 9-

anthrylnitrile with FcLi gave a 10-ferrocenyl substituted product,

in contrast to a nucleophilic attack at the C≡N functionality. Thus,

ferrocenylmethyl phosphates are not suitable for anionic homo

phospho-Fries rearrangements.

Applying ortho-P(S)Ph₂-substituted ferrocenylmethanol in an

acid-catalyzed condensation reaction produced instead of the

+

oxo- the respective thio-ether, whereby the 1,2-P(S)Ph₂,CH₂

ferrocene acted as the sulfur and the electron source. Lowering

the substrate concentration, resulted in electrophilic substitution

reactions in the presence of electron-rich aromatics.

Two stereopure ferrocenylmethyl phosphanes were used as sup-

porting ligands in Pd-catalyzed Suzuki-Miyaura C,C cross-coupl-

ing reactions for the atropselective synthesis of hindered biaryls

with up to 21 % ee. This verified that the P∙∙∙O distance between

the two donor atoms of the supporting ligand plays a decisive role

for an efficient chirality transfer from the ferrocenyl backbone to

the formed biaryl.

Electrochemistry: Electrochemical measurements of 18d and

19 (1.0 mmol L^–1) using [NⁿBu₄][B(C₆F₅)₄] (0.1 mol L^–1) as the

supporting electrolyte in anhydrous dichloromethane were

performed in a dried, argon-purged cell at 25 °C with a

Radiometer Voltalab PGZ 100 electrochemical workstation

interfaced with a personal computer.^75,76

The spectroelectrochemical measurement of 19 (Figure SI4) was

performed in an OTTLE cell (optically transparent thin-layer

electrochemistry) placed in a Varian Cary 5000 UV/Vis–NIR

absorption spectrometer using anhydrous dichloromethane

solutions containing 2.0 mmol L^–1of 20 and 0.1 mol L^–1of

[NⁿBu₄][B(C₆F₅)₄] as supporting electrolyte at 25 °C. ^77,78

Between the spectroscopic measurements the applied potentials

have been increased step-wisely 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. For the measurements,

a three-electrode cell containing a Pt auxiliary electrode, a glassy

carbon working electrode (surface area 0.031 cm²) and an Ag/Ag⁺

(0.01 mmol L^–1[AgNO₃]) reference electrode fixed on a Luggin

capillary was used. The working electrode was pretreated by

polishing with a Buehler microcloth first with a 1 micron and then

with a 1/4 micron diamond paste. The reference electrode was

constructed from a silver wire inserted into a solution of [AgNO₃]

(0.01 mmol L^–1) and an [NⁿBu₄][B(C₆F₅)₄] (0.1 mol L^–1) acetonitrile

solution in a Luggin capillary with a Vycor tip. This Luggin capillary

Experimental

General: All reactions were carried out under an atmosphere of

argon by using standard Schlenk techniques. For column

chromatography, 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 spectra follows the IUPAC recommendations.⁶⁸

Reagents: Diethyl ether, tetrahydrofuran, toluene and hexane

were purified by distillation from sodium/benzophenone ketyl;

dichloromethane, N,N-diisopropyl amine, dmf, benzonitrile and

TMEDA were purified by distillation from calcium hydride. Di(1R)-

α-fenchyl (= Fn) ferrocenyl phosphate (7),⁹triphenylbenzal-

dehyde ⁶⁹, triphenylbenzonitrile ⁷⁰and [NⁿBu₄][B(C₆F₅)₄], ⁷¹fer-

rocenyl methanol (1a),⁵⁴diphenylphosphino formylferrocene,¹⁴

benzoylferrocene (12d) ⁷², ferrocenyldiphenylmethanol (1e)⁷³and

(S_p)-(2-thiodiphenylphosphino)hydroxymethylferrocene

((S_p)-

27)¹⁴were synthesized according to published procedures. ⁿBuLi

(2.5 M in hexane), ^tBuLi (1.9 M in hexane), MeLi (1.6 M in Et₂O),

PhLi (1.9 M in ⁿBu₂O) and all other compounds mentioned herein

were purchased from commercial suppliers and were used

without further purification.

was inserted in

a second Luggin capillary containing a

[NⁿBu₄][B(C₆F₅)₄] (0.1 mol L^–1) dichloromethane solution and a

Vycor tip. Experiments under the same conditions showed that all

reduction and oxidation potentials were reproducible within ±5 mV.

10.1002/ejic.201700645

European Journal of Inorganic Chemistry

FULL PAPER

Experimental potentials were referenced against an Ag/Ag⁺

reference electrode, but the presented results are referenced

against ferrocene as an internal standard as required by IUPAC.⁷⁹

To achieve this, each experiment was repeated in the presence

of decamethylferrocene (Fc*; 1 mmol L^–1). Data were processed

with a Microsoft Excel worksheet to set the formal reduction

potentials of the FcH/FcH⁺couple⁷⁹to 0.0 V. Under our conditions,

the Fc*/Fc*⁺couple was at –614 mV vs. FcH/FcH⁺, ΔEp = 60 mV,

whereas the FcH/FcH⁺couple itself was at 220 mV vs. Ag/Ag⁺,

ΔEp = 61 mV. ⁸⁰

67.9 (C₅H₄), 68.4 (C₅H₅), 68.6 (C₅H₄), 68.7 (C₅H₄), 69.8 (CH₂),

85.4 (C_C5H4–C), 92.1 (C2). HRMS (ESI-TOF, m/z): calcd for

C₂₁H₂₈FeO 352.1484, found 352.1479 [M]⁺.

Cyclopentadien-1-yldiphenylferrocenylmethane (11a,b)

Ferrocenyldiphenylmethanol (1e, 1.00 g, 2.716 mmol) was

dissolved in diethyl ether (50 mL) and cooled to –50 °C followed

by dropwise addition of BuLi (1.1 mL, 2.75 mmol). After stirring for

10 min at this temperature and warming it afterwards to 0 °C,

diethyl chlorophosphate (2b, 0.40 mL, 2.77 mmol) was added in

a single portion, resulting in an exothermic reaction. The mixture

was allowed to warm to ambient temperature and stirring was

continued for 18 h. All volatiles were removed in vacuum.

Purification was realized by column chromatography (silica, 2 x

14 cm column size) using a 9:1 hexane/dichloromethane mixture

(v/v) as the eluent. As the first fraction, compound 10 (155 mg,

0.637 mmol, 25 % based on 1e) was eluted followed by 11. They

were obtained as orange oil (10) and solid (11) after removal of

all volatiles in vacuum. Compound 11 was obtained as a mixture

of the tautomeric forms 11a and 11b.

Single-Crystal X-ray Diffraction Analysis: Data for 1g, 8, 11b,

14, 18b,d, 19, 20, 22, (S_p,S_p)-32, (S_p)-33c, (S_p)-34a, (S_p)-37 and

(S_p)-40a were collected at ≤ 120 K with graphite-monochromated

Mo K_α(λ = 0.71073 Å) or Cu K_αradiation (λ = 1.54184 Å). The

molecular structures were solved by direct methods using

SHELXS-13⁸¹and refined by full-matrix least squares procedures

83

on F2 using SHELXL-13. ^{82 ,}

All non-hydrogen atoms were

refined anisotropically. H atoms were introduced at calculated

positions and treated as riding on their parent atoms and a riding

model was employed in the treatment of the hydrogen atom

positions, except otherwise noted. Graphics for the molecular

structures were created by using ORTEP. ⁸⁴

Yield: 251 mg (0.603 mmol, 22 % based on 1e). Anal. calcd for

C₂₈H₂₄Fe (416.34 g/mol): C, 80.78; H, 5.81. Found: C, 80.32; H,

5.86. Mp: 143 °C. HRMS (ESI-TOF, m/z): calcd for C₂₈H₂₄Fe

416.1227, found 416.1187 [M]⁺.

(1R)-α-Fenchyloxymethylferrocene (8)

Ferrocenyl methanol (1a) (2.017g, 9.335 mmol) was dissolved in

THF (20 mL) and cooled to –50 °C followed by the dropwise

addition of BuLi (4 mL, 10 mmol). Stirring was continued for 10

min and ClP(O)(OFn)₂(2a) (3.65 g, 9.39 mmol) was added with a

Pasteur pipette. The mixture was allowed to warm to ambient

Cyclopenta-1,4-dien-1-yldiphenylferrocenylmethane (11a)

¹H NMR (CDCl₃, δ): 3.05–3.06 (m, 2 H, CH₂), 3.98 (m, 7 H, C₅H_5,

C₅H₄), 1.20 (m, 2 H, C₅H₄), 5.72–5.74 (m, 1 H, CH), 6.43–6.50–

6.51 (m, 1 H, CH), 6.85–6.86 (m, 1 H, CH), 7.14–7.19 (m, 4 H,

C₆H₅), 7.20–7.25 (m, 6 H, C₆H₅). ¹³C{¹H} NMR (CDCl₃, δ): 40.1

(CH₂), 55.1 (^qC), 67.6–67.7 (C₅H₄), 69.7–69.9 (C₅H₅), 70.9–71.1

(C₅H₄), 97.4–97.5 (^qC₅H₄, HMBC), 126.1 (C4_C6H5), 127.1 (C₆H₅),

129.7 (C₆H₅), 130.1 (CH), 131.7 (CH), 136.4 (CH), 147.6 (C1_C6H5),

152.9 (^qC₅H₅–^qC).

temperature and stirring was continued for 18

h at this

temperature. All volatiles were removed in vacuum. Purification

was realized by column chromatography (silica, 4.5 x 22 cm

column size) using hexane for the elution of methylferrocene 7⁸⁵

(50 mg, 0.25 mmol, 3 % based on 1a) and 8, followed by a 1:1

hexane/dichloromethane mixture (v/v) giving bis(ferrocenyl-

methyl)ether 6a⁸⁶(886 mg, 2.14 mmol, 46 % based on 1a) and 1a

(242 mg, 1.12 mmol, 12 % based on 1a). After evaporation of all

volatiles in vacuum all compounds were obtained as orange solids.

Crystals suitable for single-crystal X-ray diffraction analysis were

obtained from boiling hexane solutions containing 8.

Cyclopenta-1,3-dien-1-yldiphenylferrocenylmethane (11b)

¹H NMR (CDCl₃, δ): 3.33 (m, 2 H, CH₂), 3.82 (pt, ³⁺⁴J_H,H= 1.7 Hz,

2 H, C₅H₄), 4.07 (s, 5 H, C₅H₅), 4.19–4.21 (m, 2 H, C₅H₄), 6.21

(dd, J_H,H= 2.1 Hz, J_H,H= 1.2 Hz, 1 H, CH), 6.43–6.51 (m, 2 H, CH),

7.04–7.06 (s, 4 H, C₆H₅), 7.20–7.25 (m, 6 H, C₆H₅). ¹³C{¹H} NMR

(CDCl₃, δ): 43.9 (CH₂), 56.4 (^qC), 67.3 (C₅H₄), 69.2 (C₅H₅), 71.2

(C₅H₄), 97.3 (^qC₅H₄), 126.2 (C4_C6H5), 127.1 (C₆H₅), 129.6 (C₆H₅),

130.9 (CH), 131.3 (CH), 132.3 (CH), 147.7 (C1_C6H5), 155.0

(^qC_C5H5–^qC).

Yield: 188 mg (0.534 mmol, 6 % based on 1a). Anal. calcd for

C₂₁H₂₈FeO∙1/8 CH₂Cl₂(352.29 ∙ 1/8 94.93 g/mol): C, 69.92; H,

1

7.85. Found: C, 69.59; H, 7.93. Mp: 157 °C. H NMR (CDCl₃, δ):

3

0.92 (s, 3 H, C(CH₃)₂), 0.96 (tdd, J_H,H= 11.9 Hz, J_H,H= 2.8 Hz,

J_H,H= 1.6 Hz, 1 H, H5/6), 1.01 (s, 3 H, C(CH₃)₂), 1.05–1.08 (m, 4

H, C1(CH₃), H7), 1.38 (tdd, ³J_H,H= 12.4 Hz, J_H,H= 5.8 Hz, J_H,H

=

4.1 Hz, 1 H, H5/6), 1.44 (ddd, ³J_H,H= 10.0 Hz, J_H,H= 4.0 Hz, J_H,H

= 2.2 Hz, 1 H, H7), 1.62–1.63 (m, 1 H, H4), 1.69 (ddt, ³J_H,H= 12.0

Hz, J_H,H= 9.1 Hz, J_H,H= 2.8 Hz, 1 H, C5/6), 2.98 (d, J_H,H= 1.8 Hz,

1 H, H2), 4.12 (pt, ³⁺⁴J_H,H= 1.9 Hz, 1 H, C₅H₄), 4.14 (s, 5 H, C₅H₅),

4.20 (d, ²J_H,H= 11.4 Hz, 1 H, CH₂), 4.22 (pt, ³⁺⁴J_H,H= 1.8 Hz, 1 H,

C₅H₄), 4.31 (d, ²J_H,H= 11.4 Hz, 1 H, CH₂). ¹³C{¹H} NMR (CDCl₃,

δ): 20.0 (C(CH₃)₂), 20.8 (C(CH₃)₂), 26.0 (C5/6), 26.2 (C5/6), 31.6

(C1(CH₃)), 39.4 (C3), 41.4 (C7), 48.8 (C4), 49.2 (C1), 67.8 (C₅H₄),

2-Ferrocenyl-2-adamantanol (14)

Ferrocene (13, 2.00 g, 10.75 mmol) and KO^tBu (163 mg, 1.45

mmol) were dissolved in 50 mL of THF and cooled to –80 °C.

t

Afterward, BuLi (5.7 mL, 10.83 mmol) was dropwise added, the

mixture was stirred for 30 min at this temperature followed by the

addition of 2-adamantanone (1.776 g, 11.82 mmol). The mixture

was allowed to warm to ambient temperature and stirred for

10.1002/ejic.201700645

European Journal of Inorganic Chemistry

FULL PAPER

additional 18 h. All volatiles were removed in vacuum. Purification

was realized by column chromatography (silica, 4 x 14 cm column

size) using hexane for the removal of ferrocene followed by

dichloromethane for the elution of 14. After removal of all volatiles

in vacuum, compound 14 was obtained as an orange solid.

volatiles were removed in vacuum. Purification was realized by

column chromatography (silica, 2 x 12 cm column size) using

dichloromethane as the eluent for removing unreacted nitrile 17

(40 mg, 17

%

based on 17) followed by

a

9:1

dichloromethane/ethyl acetate mixture (v/v) for eluting 18a. After

removal of all volatiles, compound 18a was obtained as a red oil

in a 1:0.07 ratio of the (E)- to the (Z)-diastereomer.

Yield: 2.635 g (7.84 mmol, 73 % based on 13). Anal. calcd for

C₂₀H₂₄FeO ∙ 1/6 C₆H₁₄(366.25 ∙ 1/6 86.18 g/mol): C, 71.94; H,

1

7.57. Found: C, 71.98; H, 7.33. Mp: 114 °C. H NMR (CDCl₃, δ):

Yield: 378 mg (0.65 mmol, 60 % based on 17). Anal. calcd for

C₃₂H₄₆FeNO₃P ∙ 0.5 H₂O (579.53 ∙ 0.5 18.01 g/mol): C, 65.30; H,

8.05; N, 2.38. Found: C, 65.35; H, 7.91; N, 2.10. ¹H NMR (CDCl₃,

δ): 0.97 (s, 3 H, CH₃), 1.02 (s, 3 H, CH₃), 1.03 (m, 2 H, H5/6,

HSQC), 1.09 (s, 3 H, CH₃), 1.10 (s, 3 H, CH₃), 1.16 (m, 2 H, H7,

HSQC), 1.17 (s, 3 H, CH₃), 1.20 (s, 3 H, CH₃), 1-40–1.47 (m, 2 H,

H5/6), 1.51–1.53 (m, 2 H, H7), 1.70–1.75 (m, 4 H, H5/6/7), 1.76–

1.82 (m, 2 H, H5/6), 2.62 (d, ⁴J_H,P= 2.3 Hz, 3 H, CH₃–C=N), 4.01

1.58–1.60 (m, 1 H, H5/H7), 1.60–1.62 (m, 1 H, H5/H7), 1.63–1.72

(m, 7 H), 1.81–1.83 (m, 1 H, H5/7), 1.91–1.93 (m, 2 H, H1/3),

2.47–2.50 (m, 1 H, CH₂), 2.50–2.53 (m, 1 H, CH₂), 2.82 (s, 1 H,

3+4

OH), 4.20 (pt,

J

= 1.7 Hz, 2 H, C₅H₄), 4.24 (s, 5 H, C₅H₅),

H,H

3+4

4.38 (pt,

J

= 1.6 Hz, 2 H, C₅H₄). ¹³C {¹H} NMR (CDCl₃, δ):

H,H

27.2 (C5/7), 27.2 (C5/7), 33.7 (C4/6/9/10), 35.3 (C4/6/9/10), 38.0

(C8), 38.8 (C1/3), 67.2 (C₅H₄), 67.7 (C₅H₄), 68.2 (C₅H₅), 72.0 (C2),

102.3 (^qC₅H₄). UV/Vis (in nm (ε in L mol^–1cm^–1), CH₂Cl₂): 329 (66),

447 (121). HRMS (ESI-TOF, m/z): calcd for C₂₀H₂₄FeO

336.11711, found 336.1170 [M]⁺.

3

(dd, J_H,P= 9.3 Hz, J_H,H= 1.8 Hz, 1 H, H2), 4.04 (dd, J_H,P= 9.6

Hz, J_H,H= 1.7 Hz, 1 H, H2), 4.18 (s, 5 H, C₅H₅, major), 4.20 (s, 5

H, C₅H₅, minor), 4.49–4.50 (m, 2 H, C₅H₄), 4.78 (dpt, J_H,H= 2.5

Hz, J_H,H= 1.4 Hz, 1 H, C₅H₄), 4.81 (dpt, J_H,H= 2.6 Hz, J_H,H= 1.4

Hz, 1 H, C₅H₄). ¹³C{¹H} NMR (CDCl₃, δ): 19.1 (CH₃), 19.8 (CH₃),

21.1 (CH₃), 21.2 (CH₃), 24.0 (d, ³J_C,P= 10.8 Hz, CH₃–C=N), 25.9

(C5/6), 25.99 (C5/6), 26.02 (C5/6), 26.1 (C5/6), 29.9 (CH₃), 30.1

(CH₃), 39.46 (d, ³J_C,P= 2.1 Hz, C3), 39.48 (d, ³J_C,P= 1.9 Hz, C3),

2-Ferrocenyl-2-methyl-4-(prop-1-en-2-yl)cyclohexanone (15c)

Compound 15a (300 mg, 0.887 mmol) was dissolved in 20 mL of

n

diethyl ether and cooled to –80 °C. Buli (0.35 mL, 0.875 mmol)

3

41.0 (C7), 48.00 (C4), 48.06 (C4), 49.3 (d, J_C,P= 4.7 Hz, C1),

was dropwise added and the mixture was slowly warmed to –

30 °C followed by the dropwise addition of ClP(O)(OEt)₂(2b, 0.13

mL 0.90 mmol). After stirrting for 18 h at ambient temperature all

volatiles were removed in vacuum. Purification was realized by

49.4 (d, ³J_C,P= 4.9 Hz, C1), 69.7 (d, J_C,P= 1.0 Hz, C₅H₄), 69.8 (d,

J_C,P= 1.2 Hz, C₅H₄), 69.9 (C₅H₅), 72.16 (C₅H₄), 72.18 (C₅H₄), 82.9

(d, ³J_C,P= 34.4 Hz, +C₅H₄), 89.18 (d, ²J_C,P= 7.3 Hz, C2), 89.22 (d,

2

²J_C,P= 7.7 Hz, C2), 186.2 (d, J_C,P= 1.7 Hz, C=N). ³¹P{¹H} NMR

column chromatography (silica, 2.5

x

12 cm) using

(CDCl₃, δ): 4.05 (minor), 4.18 (major). IR data (KBr, ν/cm^–1): 3094

m, 2955 s, 2926 m, 2867 m, 1673 s, 1611 s (v C=N), 1452 s, 1377

m, 1244 m, 1062 w, 1036 s, 1007 s, 929 m, 919 m, 819 m. UV/Vis

(in nm (ε in L mol^–1cm^–1), CH₂Cl₂): 275 (7909), 464 (684). HRMS

(ESI-TOF, m/z): calcd for C₃₂H₄₆FeNO₃P+H 580.2638, found

580.2590 [M+H]⁺.

dichloromethane as the eluent. The title compound was obtained

as an orange solid.

Yield: 24 mg (0.071 mmol, 8 % based on 15a). ¹H NMR (CDCl₃,

δ): 1.45 (s, 3 H, CH₃), 1.47–1.52 (m, 1 H, CH₂), 1.54–1.60 (m, 1

H, CH₂), 1.75* (s, 3 H, CH₃), 1.82 (ddd, J_H,H= 12.9 Hz, J_H,H= 6.8

Hz, J_H,H= 1.0 Hz, 1 H, CH₂), 1.87–1.93 (m, 1 H, CH₂), 2.23 (dd,

J_H,H= 12.8 Hz, J_H,H= 11.5 Hz, 1 H, CH₂), 2.626 (ddd, ²J_H,H= 11.8

(E)-Bis((1R)-α-fenchyl)(ferrocenyl(phenyl)methylene)phosphor-

amidate (18b)

3

Hz, J_H,H= 8.3 Hz, J_H,H= 2.9 Hz, 1 H, CH₂), 2.64–2.68 (m, 1 H,

CH), 4.18 (s, 5 H, C₅H₅), 4.47 (pt, ³⁺⁴J_H,H= 2.0 Hz, 4.70–4.72 (m,

1 H, =CH₂), 4.75–4.76 (m, 1 H, =CH₂), 4.78–4.79 (m, 1 H, C₅H₄),

4.80–4.81 (m, 1 H, C₅H₄). ¹³C{¹H} NMR (CDCl₃, δ): 21.2 (CH₃),

28.3 (CH₃), 31.0 (CH₂), 36.8 (CH₂), 42.6 (CH₂), 46.0 (CH), 54.9

(^qC), 69.8 (C₅H₅), 70.76 (C₅H₄), 70.83 (C₅H₄), 71.2 (C₅H₄), 71.3

(C₅H₄), 76.8 (^qC), 108.7 (CH₂), 147.8 (^qC), 209.8 (C=O). HRMS

(ESI-TOF, m/z): calcd for C₂₀H₂₄FeO 336.1171, found 336.1163

[M]⁺. * See, Supporting Information.

Ferrocene (13, 1,30 g; 7,00 mmol) and KO^tBu (96 mg, 0.79 mmol)

were dissolved in 50 mL of THF and cooled to –80 °C followed by

the dropwise addition of ^tBuLi (3.35 mL, 6.35 mmol). The orange

suspension was stirred for 30 min and benzonitrile (0.66 mL, 6.40

mmol) was dropwise added. The mixture was allowed to warm to

ambient temperature and stirring was continued until the solution

turned dark-red. Afterward, chlorophosphate 2a (1.95 g, 5.01

mmol) was added with a Pasteur pipette and stirring was

continued for 18 h. All volatiles were removed in vacuum.

Purification was realized by column chromatography (silica, 4 x

12 cm column size) using a 1:1 hexane/dichloromethane mixture

(v/v) to elute the excess of 13 (421 mg, 2.27 mmol), followed by a

9:1 dichloromethane/ethyl acetate mixture (v/v) as the eluent for

12d (17 %) and a 4:1 dichloromethane/ethyl acetate mixture (v/v)

for 18b. After removal of all volatiles in vacuum, compound 18b

was obtained as a red solid in a 1:0.11 ratio of the (E)- to the (Z)-

diastereomer.

(E)-Bis((1R)-α-fenchyl)(1-ferrocenylethylidene)phosphoramidate

(18a)

Ferrocenylnitrile (17, 230 mg, 1.09 mmol) was dissolved in 20 mL

of THF and this mixture was cooled to –80 °C. A 1.6 M solution of

MeLi in diethyl ether (0.68 mL, 1.09 mmol) was dropwise added.

The mixture was allowed to warm to –30 °C, stirred for 30 min at

this temperature and afterward 2a (423 mg, 1.09 mmol) was

added with a Pasteur pipette. After warming the reaction mixture

to ambient temperature, stirring was continued for 18 h. All

10.1002/ejic.201700645

European Journal of Inorganic Chemistry

FULL PAPER

Yield: 1.864 g (2.906 mmol, 58 % based on 2a). Anal. calcd for

C₃₇H₄₈FeNO₃P ∙ 0.5 H₂O (641.61 ∙ 0.5 18.01 g/mol): C, 68.31; H,

7.59; N, 2.15. Found: C, 68.07; H, 7.58; N, 2.12. Mp: 156 °C. H

3 H, CH₃), 1.33–1.41 (m, 3 H, C₁₀H₁₇), 1.48–1.54 (m, 4 H, C₁₀H₁₇),

1.64–1.68 (m, 2 H, C₁₀H₁₇), 3.58 (s, 5 H, C₅H₅), 4.06–4.07 (m, 1

H, C₅H₄), 4.08–4.10 (m, 1 H, C₅H₄), 4.10–4.12 (m, 1 H, C₅H₄),

4.15–4.16 (m, 1 H, C₅H₄), 4.25–4.28 (m, 2 H, H2), 7.24–7.28 (m,

1 H), 7.31–7.38 (m, 6 H), 7.43–7.46 (m, 2 H), 7.48–7.49 (m, 1 H),

7.53–7.54 (m, 1 H), 7.63–7.65 (m, 4 H), 7.71–7.73 (m, 2 H).

¹³C{¹H} NMR (CDCl₃, δ): 19.8 (CH₃), 19.9 (CH₃), 21.3 (CH₃), 21.9

(CH₃), 25.8 (CH₂), 25.96 (CH₂), 26.00 (CH₂), 29.9 (CH₃), 30.0

1

NMR (CDCl₃, δ): 0.77–0.80 (m, 4 H, CH₃, C₁₀H₁₇), 0.85 (s, 3 H,

CH₃), 0.88–0.99 (m, 1 H, C₁₀H₁₇), 1.06–1.13 (m, 14 H, CH₃,

C₁₀H₁₇), 1.16–1.21 (m, 1 H, C₁₀H₁₇), 1.29–1.39 (m, 2 H, C₁₀H₁₇),

1.46–1.57 (m, 5 H, C₁₀H₁₇), 1.63–1.66 (m, 2 H, C₁₀H₁₇), 4.00 (dd,

3

³J_H,P= 9.2 Hz, J_H,H= 1.7 Hz, 1 H, H2), 4.10 (dd, J_H,P= 9.5 Hz,

3

J_H,H= 1.7 Hz, 1 H, H2), 4.22 (s, 4.5 H, C₅H₅, major), 4.23 (s, 0.5

H, C₅H₅, minor), 4.49–4.51 (m, 2 H, C₅H₄), 4.59–4.61 (m, 1 H,

C₅H₄), 4.66–4.68 (m, 1 H, C₅H₄), 7.37–7.40 (m, 3 H, C₆H₅), 7.61–

7.63 (m, 1.78 H, C₆H₅, major), 7.66–7.68 (m, 0.22 H, C₆H₅, minor).

¹³C{¹H} NMR (CDCl₃, δ): 19.5 (CH₃), 19.6 (CH₃), 20.8 (CH₃), 21.1

(CH₃), 25.6 (C5/6), 25.8 (C5/6), 25.9 (C5/6), 26.0 (C5/6), 29.9

(CH₃), 30.1 (CH₃), 39.2 (d, ³J_C,P= 2.0 Hz, C3), 39.6 (d, ³J_C,P= 2.4

Hz, C3), 40.99 (C7), 41.03 (C7), 47.95 (C4), 47.98 (C4), 49.1 (d,

³J_C,P= 4.6 Hz, C1), 49.2 (d, ³J_C,P= 4.9 Hz, C1), 70.1 (C₅H₅), 71.4

(C₅H₄), 71.6 (C₅H₄), 72.3 (C₅H₄), 72.4 (C₅H₄), 82.6 (d, ³J_C,P= 2.0

(CH₃), 39.4 (d, J_C,P= 1.4 Hz, C3), 40.0 (d, J_C,P= 0.7 Hz, C3),

41.1 (C7), 41.4 (C7), 47.8 (C4), 48.0 (C4), 49.3 (d, ³J_C,P= 5.4 Hz,

3

C1), 49.4 (d, J_C,P= 5.1 Hz, C1), 69.4 (C₅H₅), 70.1 (C₅H₄), 70.3

(C₅H₄), 70.9 (C₅H₄), 71.6 (C₅H₄), 84.9 (d, ³J_C,P= 29.5 Hz, ⁱC₅H₄),

2

89.8 (d, J_C,P= 7.6 Hz, C2), 90.2 (d, J_C,P= 8.3 Hz, C2), 127.1

(CH), 127.3 (CH), 127.4 (CH), 127.6 (CH), 127.8 (CH), 128.0 (CH),

128.6 (CH), 128.6 (CH), 128.8 (CH), 130.4 (CH), 130.4 (CH),

138.2 (^qC), 138.3 (^qC), 139.7 (^qC), 139.8 (^qC), 140.2 (^qC), 140.78

2

(^qC), 140.83 (^qC), 140.9 (^qC), 181.3 (d, J_C,P= 2.7 Hz, C=N).

³¹P{¹H} NMR (CDCl₃, δ): 0.9 (minor), 1.7 (major). UV/Vis (in nm (ε

in L mol^–1cm^–1), CH₂Cl₂): 372 (1281), 502 (1106). HRMS (ESI-

TOF, m/z): calcd for C₅₅H₆₀FeNO₃P+H 870.3734, found 870.3749

[M+H]⁺.

3

2

Hz, C3), 82.6 (d, J_C,P= 31.5 Hz, ^qC₅H₄), 89.1 (d, J_C,P= 8.3 Hz,

C2), 89.2 (d, ²J_C,P= 8.1 Hz, C1), 127.7 (C₆H₅), 127.6 (C₆H₅), 129.1

3

2

(C4_C6H5), 139.9 (d, J_C,P= 11.6 Hz, C1_C6H5), 183.8 (d, J_C,P= 2.5

Hz, C=N). ³¹P{¹H} NMR (CDCl₃, δ): 2.1 (1, major), 2.3 (0.11,

minor). IR data (NaCl/CHCl₃, ν/cm^–1): 2958 s, 2870 m, 1611 s,

1591 w, 1572 w, 1452 m, 1377 w, 1293 m, 1056 s, 923 s. IR data

(KBr, ν/cm^–1): 3093 w, 3047 w, 3029 w, 2945 s, 2920 s, 2868 s,

1608 s (ν_N=C), 1596 w, 1577 m, 1447 m, 1438 w, 1376 m, 1358 w,

1336 w, 1293 m, 1274 w, 1243 s, 1055 s, 1008 s, 918 s. UV/Vis

(in nm (ε in L mol^–1cm^–1), CH₂Cl₂): 362 (1652), 484 (1117). HRMS

(ESI-TOF, m/z): calcd for C₃₇H₄₈FeNO₃P+H 642.2795, found

642.2782 [M+H]⁺.

Synthesis of 18d and 19

Two synthetic methodologies to prepare the title compounds

exist:

A) Reaction of 17 with ^tBuLi and 2a

Compound 17 (500 mg, 2.37 mmol) was dissolved in 30 mL of

THF. At –80 °C ^tBuLi (1.25 mL, 2.38 mmol) was dropwise added.

The mixture was allowed to warm to ambient temperature and

stirred until the color changed to dark red. Afterward, 2a (921 mg,

2.37 mmol) was added with a Pasteur pipette and stirring was

continued for 18 h. All volatiles were removed in vacuum.

Purification was realized by column chromatography using the

same conditions as given under B). First 19 (311 mg, 0.58 mmol,

49 % based on 17) was eluted, followed by 18d as a 1:2 mixture

with 5a (835 mg, 25 % of 18d based on 17).

(E)-Bis((1R)-α-fenchyl)(1-ferrocenyl(2,4,6-triphenylphenyl)

methylene)phosphoramidate (18c)

According to the synthesis of 14, ferrocene (13, 1.30 g, 6.99

mmol), KO^tBu (96 mg, 0.79 mmol) and ^tBuLi (3.4 mL, 6.46 mmol)

were reacted for the synthesis of 13–Li. After stirring for 30 min at

–80 °C, 2,4,6-triphenylbenzonitrile (1.41 g, 4.25 mmol) was added

in a single portion and the mixture was allowed to warm to

ambient temperature. Stirring was continued until the color

changed from orange to deep red followed by the addition of 2a

(1.66 mg, 4.27 mmol) by using a Pasteur pipette. After stirring for

18 h at ambient temperature, all volatiles were removed in

vacuum. Purification was realized by column chromatography

B) Reaction of 13–Li with tertbutylnitrile

According to the synthesis of 14, ferrocene (13, 1.30 g, 6.99

t

mmol), KO^tBu (96 mg, 0.79 mmol), BuLi (3.4 mL, 6.46 mmol),

(silica,

4

x

16 cm column size) using

a

1:1

tertbutylnitrile (0.70 g, 8.42 mmol) and 2a (2.44 g, 6.27 mmol)

were reacted. All volatiles were removed in vacuum. Purification

was realized by column chromatography (silica, 2 x 15 cm column

size) using hexane to elute the excess of 13 followed by a 1:4

hexane/dichloromethane mixture (v/v) as the eluent for 19. The

solvent was changed to dichloromethane and finally a 9:1

dichloromethane/ethyl acetate mixture (v/v) was used for 12f (430

hexane/dichloromethane mixture (v/v) to elute the excess of 13

followed by a 9:1 dichloromethane/ethyl acetate mixture (v/v) as

the eluent for 18c. After removal of volatiles in vacuum gave

compound 18c as a red solid and a mixture of the E- and Z-

isomers of 1:0.08. Crystals suitable for single crystal X-ray

diffraction analysis were obtained by crystallization from ethanol.

t

mg, 1.59 mmol, 25 % based on BuLi) and 18d (538 mg, 25 %

based on ^tBuLi). All volatiles were removed in vacuum.

Yield: 715 mg (0.822 mmol, 19

%

based on 2,4,6-

triphenylbenzonitrile). Anal. calcd for C₅₅H₆₀FeNO₃P (869.89

g/mol): C, 75.94; H, 6.95; N, 1.61. Found: C, 75.62; H, 7.22; N,

1.53. Mp: 140–145 °C. H NMR (CDCl₃, δ): 0.66 (s, 3 H, CH₃),

tertButylferrocenyl imino phosphate (18d)

1

0.77–0.91 (m, 2 H, C₁₀H₁₇), 1.00–1.18 (m, 15 H, C₁₀H₁₇), 1.24 (s,

10.1002/ejic.201700645

European Journal of Inorganic Chemistry

FULL PAPER

Compound 18d was obtained as a red oil with a ratio of the E-/Z-

isomers of 0.259:1 (de = 0.59). The two sets of signals in the ¹H,

¹³C{¹H} and ³¹P{¹H} NMR were assigned as major (ma) and minor

(mi). The title compound occurred in a 1:2 mixture of the

phosphate 18d with the bis-(1R)-α-fenchyl phosphate (5a). The

signals of 5a have been avoided for clarity, but are present in the

NMR spectra in the ESI.

mixture was stirred at 50 °C for 18 h, whereby the color changed

from red to yellow. The reaction mixture was poured into ice-water

(200 mL) and extracted with diethyl ether (3 x 50 mL). The organic

layers were combined, dried over MgSO₄followed by removal of

all volatiles in vacuum. Purification was realized by column

chromatography (alumina, 2 x 10 cm column size) using

dichloromethane as the eluent (R_f= 0.60). After removal of all

volatiles compound 20 was obtained as a yellow solid and as a

ratio of three isomers of 1:0.86:0.23.

Yield: 538 mg (1.62 mmol, 25 % based on ^tBuLi). Anal. calcd for

C₃₅H₅₂FeNO₃P ∙ 2 C₂₀H₃₅O₄P ∙ CH₂Cl₂(621.61 ∙ 2 370.46 ∙ 1 84.93

g/mol): C, 63.06; H, 8.63; N, 0.97. Found: C, 62.88; H, 8.26; N,

1.02. ¹H NMR (CDCl₃, δ): 0.89 (s, 3 H, CH₃), 0.92 (s, 3 H, CH₃),

1.04 (s, 3 H, CH₃), 1.06 (s, 3 H, CH₃), 1.11 (s, 3 H, CH₃), 1.14 (s,

Yield: 90 mg (0.14 mmol, 72 % based on 18b). Anal. calcd for

C₃₇H₅₀FeNO₃P (643.62 g/mol): C, 69.05; H, 7.83; N, 2.18. Found:

C, 68.73; H, 8.00; N, 2.04. Mp: 134–136 °C. ¹H NMR (CDCl₃, δ):

0.84–1.70 (m, 32 H), 3.12 (dd, ²J_H,P= 9.2 Hz, ³J_H,H= 9.2 Hz, NH),

3.18 (dd, ²J_H,P= 9.7 Hz, ³J_H,H= 8.1 Hz, NH), 3.27 (dd, ²J_H,P= 9.4

Hz, ³J_H,H= 9.4 Hz, NH), 3.63 (dd, ³J_H,P= 9.2 Hz, J_H,H= 1.7 Hz, H2),

3

3 H, CH₃), 3.99 (dd, J_H,P= 8.9 Hz, J_H,H= 1.7 Hz, 1 H, H2), 4.03

(dd, ³J_H,P= 9.0 Hz, J_H,H= 1.7 Hz, 1 H minor, H2), 4.09 (dd, ³J_H,P

=

9.1 Hz, J_H,H= 1.6 Hz, 1 H, H2), 4.22 (s, 5 H, C₅H₅), 4.46–4.48 (m,

2 H, C₅H₄), 5.23 (dpt, J_H,H= 2.8 Hz, J_H,H= 1.4 Hz, 1 H, C₅H₄), 5.25

(dpt, J_H,H= 2.5 Hz, J_H,H= 1.5 Hz, 1 H, C₅H₄). ¹³C{¹H} NMR (CDCl₃,

δ): 19.6 (CH₃), 19.89 (CH₃, mi), 19.92 (CH₃, mi), 25.92 (CH₂),

25.94 (CH₂), 26.0 (CH₂), 26.1 (CH₂), 29.8 (CH₃), 30.0 (CH₃), 30.9

(C(CH₃)₃), 31.5 (C(CH₃)₃, mi), 39.55 (C3), 39.57 (C3), 41.0 (C7),

41.1 (C7), 44.65 (d, ³J_C,P= 21.0 Hz, C(CH₃)₃, mi), 44.69 (d, ³J_C,P

= 21.1 Hz, C(CH₃)₃), 47.9 (C4), 48.1 (C4), 49.33 (C1), 49.35 (C1),

49.39 (C1), 70.20 (C₅H₅, mi), 70.22 (C₅H₅), 70.85 (C₅H₄, mi),

70.87 (C₅H₄), 70.94 (C₅H₄), 72.4 (C₅H₄), 72.6 (C₅H₄, mi), 72.9

3

3.66 (dd, J_H,P= 9.6 Hz, J_H,H= 1.7 Hz, H2), 3.87 (dd, J_H,P= 9.5

Hz, J_H,H= 1.6 Hz, H2), 3.89–3.96 (m, 2 H, H2, C₅H₄), 4.10–4.12

(m, 3 H, C₅H₄), 4.15/4.16 (s, 5 H, C₅H₅), 5.21 (dd, ³J_H,H= 8.8 Hz,

³J_H,P= 8.3 Hz, CH), 5.25 (dd, ³J_H,H= 9.8 Hz, ³J_H,P= 8.2 Hz, CH),

7.22–7.27 (m, 1 H, C₆H₅), 7.30–7.40 (m, 4 H, C₆H₅). ¹³C{¹H} NMR

(CDCl₃, δ): 19.5 (CH₃), 19.60 (CH₃), 19.63 (CH₃), 20.7 (CH₃),

20.91 (CH₃), 20.92 (CH₃), 21.1 (CH₃), 21.2 (CH₃), 21.3 (CH₃), 25.6

(CH₂), 25.7 (CH₂), 25.8 (CH₂), 25.9 (CH₂), 25.97 (CH₂), 25.99

(CH₂), 26.01 (CH₂), 29.6 (CH₃), 29.7 (CH₃), 29.8 (CH₃), 29.8 (CH₃),

39.15 (d, ³J_C,P= 2.0 Hz, C3), 39.24 (d, ³J_C,P= 1.8 Hz, C3), 39.4 (d,

³J_C,P= 1.3 Hz, C3), 39.6 (d, ³J_C,P= 1.4 Hz, C3), 40.8 (C7), 40.89

(C7), 40.97 (C7), 41.00 (C7), 47.95 (C4), 47.97 (C4), 48.12 (C4),

3

i

3

(C₅H₄), 78.2 (d, J_C,P= 10.0 Hz, C₅H₄), 78.6 (d, J_C,P= 10.4 Hz,

ⁱC₅H₄), 89.4 (d, ²J_C,P= 8.2 Hz, C2, mi), 89.4 (d, ²J_C,P= 8.1 Hz, C2),

89.7 (d, ²J_C,P= 8.6 Hz, C2), 191.5 (d, ²J_C,P= 4.4 Hz, C=N), 191.8

(d, ²J_C,P= 4.7 Hz, C=N, mi). ³¹P{¹H} NMR (CDCl₃, δ): –1.8 (ma), –

1.3 (mi). IR data (NaCl/CHCl₃, ν/cm^–1): 2961 s, 2874 s, 1715 m,

1585 m, 1468 m, 1286 m, 1027 s, 1017 s, 962 s. UV/Vis (in nm (ε

3

48.15 (C4), 49.0 (d, J_C,P= 4.1 Hz, C1), 49.1 (d, J_C,P= 3.2 Hz,

2

C1), 49.12 (C1), 49.13 (C1), 49.2 (C1), 54.9 (d, J_C,P= 0.7 Hz,

CH–N), 55.0 (CH–N), 55.1 (d, ²J_C,P= 0.8 Hz, CH–N), 66.6 (C₅H₄),

in L mol^–1cm^–1), CH₂Cl₂): 281 (8211), 460 (724). HRMS (ESI-TOF, 66.7 (C₅H₄), 66.8 (C₅H₄), 67.5 (C₅H₄), 67.6 (C₅H₄), 67.68 (C₅H₄),

m/z): calcd for C₃₅H₅₂FeNO₃P+H 622.3107, found 622.3078

[M+H]⁺.

67.74 (C₅H₄), 67.86 (C₅H₄), 67.93 (C₅H₄), 68.1 (C₅H₄), 68-6 (C₅H₅),

2

68.7 (C₅H₅), 88.3 (d, J_C,P= 6.2 Hz, C2), 88.4 (d, J_C,P= 6.5 Hz,

2

C2), 88.95 (d, J_C,P= 6.4 Hz, C2), 88.98 (d, J_C,P= 7.2 Hz, C2),

89.3 (d, ²J_C,P= 7.0 Hz, C2), 93.5 (d, ³J_C,P= 10.6 Hz, ⁱC₅H₄), 93.6

(d, ³J_C,P= 10.9 Hz, ⁱC₅H₄), 93.8 (d, ³J_C,P= 10.6 Hz, ⁱC₅H₄), 126.98

(C₆H₅), 127.02 (C₆H₅), 127.2 (C₆H₅), 127.3 (C₆H₅), 127.4 (C₆H₅),

127.91 (C₆H₅), 127.95 (C₆H₅), 128.03 (C₆H₅), 143.31 (ⁱC₆H₅),

143.33 (ⁱC₆H₅), 143.35 (ⁱC₆H₅). ³¹P{¹H} NMR (CDCl₃, δ): 6.9 (0.86),

7.3 (1.0), 7.4 (0.23). IR data (KBr, ν/cm^–1): 3185 s (ν_NH), 3101 w,

3062 w, 3026 w, 2951 s, 2926 m, 2870 m, 1734 w, 1708 vw, 1637

vw, 1601 w, 1455 s, 1374 m, 1361 w, 1328 w, 1309 w, 1234 s,

1225 s, 1108 m, 1053 s, 1030 s, 1004 s, 926 m, 816 m. UV/Vis

(in nm (ε in L mol^–1cm^–1), CH₂Cl₂): 431 (125). HRMS (ESI-TOF,

m/z): calcd for C₃₇H₅₀FeNO₃P 643.2873, found 643.2882 [M]⁺.

(1Z,2Z)-tertButylferrocenyl ketazine (19)

Compound 19 was obtained as a red solid in a mixture with the

(Z,E)-diastereomer in a ratio of 1:0.09. Yield: 380 mg (0.71 mmol;

22 % based on ^tBuLi). Anal. calcd for C₃₀H₃₆Fe₂N₂(536.32 g/mol):

C, 67.19; H, 6.77; N, 5.22. Found: C, 66.99; H, 6.69; N, 5.08. Mp:

148 °C. ¹H NMR (CDCl₃, δ): 1.54 (s, 9 H, CH₃), 4.14 (s, 5 H, C₅H₅),

4.30 (pt, ³⁺⁴J_H,H= 2.0 Hz, 2 H, C₅H₄), 4.79 (pt, ³⁺⁴J_H,H= 2.0 Hz, 2

H, C₅H₄). ¹³C{¹H} NMR (CDCl₃, δ): 30.4 (CH₃), 39.7 (C(CH₃)₃),

69.0 (C₅H₄), 69.4 (C₅H₅), 71.6 (C₅H₄), 75.9 (^qC₅H₄), 156.6 (C=N).

IR data (NaCl/CHCl₃, ν/cm^–1): 3098 w, 3007 m, 2990 s, 2952 m,

2932 w, 2903 w, 2867 w, 1770 w, 1692 w, 1650 w, 1559 s, 1474

s, 1455 m, 1390 s, 1367 s, 1104 s, 1069 s, 1004 m, 984 w, 884

m. UV/Vis (in nm (ε in L mol^–1cm^–1), CH₂Cl₂): 463 (883). HRMS

(ESI-TOF, m/z): calcd for C₃₀H₃₆Fe₂N₂536.1573, found 536.1585

[M]⁺.

10-Ferrocenyl-9-carbonitrile (22)

According to the synthesis of 14, ferrocene (13, 1.30 g, 6.99

mmol), KO^tBu (96 mg, 0.79 mmol) and ^tBuLi (3.4 mL, 6.46 mmol),

anthracene-9-carbonitrile (1.29 g, 6.35 mmol) and 2a (2.435 g,

6.26 mmol) were reacted. Purification was realized by column

chromatography (silica, 2.5 x 22 cm column size) using hexane to

remove the excess of ferrocene, followed by a 1:1 hexane/toluene

mixture (v/v) giving the starting nitrile (82 mg) as the 1^st, and 22

as the 2^ndfraction. It should be noted that both anthracenes, the

O,O’-Bis((1R)-α-fenchyl)(ferrocenyl(phenyl)methyl)phosphor-

amidate (20)

Compound 18b (125 mg, 0.196 mmol) was dissolved in 2 mL of

THF. NaBH₄(7.5 mg, 0.2 mmol) was carefully added and the

10.1002/ejic.201700645

European Journal of Inorganic Chemistry

FULL PAPER

starting material and 22, behave similar on the column. The

success of the separation on the column could be observed by

using UV-radiation showing the starting nitrile as a fluorescent

band. After removal of all volatiles compound 22 was obtained as

a dark solid.

Compound (S_p)-27, p-TsOH (1.37 g, 7.2 mmol), sulfur (100 mg,

3.12 mmol) and MgSO₄(1 g) (1.0 g, 2.4 mmol) were dissolved in

70 mL of toluene. The reaction mixture was heated to 90 °C and

stirred for 24 h at this temperature followed by removal of all

volatiles in vacuum. Purification was realized by column

chromatography (silica, 2.5 x 12 cm column size) using a 7:3

hexane/dichloromethane mixture (v/v) as the eluent. After

evaporation in vacuum, (S_p)-33 was obtained as an orange solid

and as a 2:1:6 mixture of of the ortho- ((S_p)-33a) / meta- ((S_p)-

33b) / para-isomers ((S_p)-33c). The three isomers showed an

equal behavior during the column chromatographic work-up

process and could thus, not be separated. The yields of each

isomer are based on the ratios of the integrals in the NMR spectra.

Yield: 207 mg (0.53 mmol, 8 % based on anthracene-9-

carbonitrile). Anal. calcd for C₂₅H₁₇FeN (387.25 g/mol): C, 77.54;

H, 4.42; N, 3.62. Found: C, 77.16; H, 4.59; N, 3.84. Mp: 218 °C.

¹H NMR (CDCl₃, δ): 4.22 (s, 5 H, C₅H₅), 4.66 (pt, ³⁺⁴J_H,H= 1.8 Hz,

2 H, C₅H₄), 4.81 (pt, ³⁺⁴J_H,H= 1.8 Hz, 2 H, C₅H₄), 7.56 (ddd, ³J_H,H

= 8.9 Hz, ³J_H,H= 6.5 Hz, ⁴J_H,H= 1.2 Hz, 2 H, H2/3), 7.67 (ddd, ³J_H,H

= 8.6 Hz, ³J_H,H= 6.5 Hz, ⁴J_H,H= 1.0 Hz, 2 H, H2/3), 8.45 (dd, ³J_H,H

= 8.7 Hz, ⁴J_H,H= 1.1 Hz, 2 H, H4/5), 9.24 (dd, ³J_H,H= 8.8 Hz, ⁴J_H,H

= 1.3 Hz, 2 H, H1/8). ¹³C{¹H} NMR (CDCl₃, δ): 68.7 (C₅H₄), 70.2

(C₅H₅), 73.9 (C₅H₄), 82.9 (ⁱC₅H₄), 105.1 (C9), 118.0 (C≡N), 124.9

(CH), 125.6 (CH), 128.3 (CH), 128.6 (CH), 130.1 (^qC), 133.1 (^qC),

140.7 (^qC). UV/Vis (in nm (ε in L mol^–1cm^–1), CH₂Cl₂): 375 (5581),

408 (10230), 424 (9248), 536 (1850). HRMS (ESI-TOF, m/z):

calcd for C₂₅H₁₇FeN 387.0705, found 387.0689 [M]⁺. IR data (KBr,

ν/cm^–1): 3094 w, 3081 w, 3046 w, 3020 w, 2955 w, 2919 w, 2851

w, 2208 s, 1621 w, 1556 s, 1442 s, 1273 m, 1104 m, 1036 m, 838

m, 767 vs, 653 m.

Yield: 862 mg (1.7 mmol, 71 % based on (S_p)-27). Anal. calcd for

C₃₀H₂₇FePS (506.42 g/mol): C, 71.15; H, 5.37. Found: C, 70.25;

H, 6.13 (best match). Mp: > 135 °C. HRMS (ESI-TOF, m/z): calcd

for C₃₀H₂₇FePS 506.0915, found 506.0901 [M]⁺.

(S_p)-2-(2Methylphenylmethyl)-1-

(thiodiphenylphosphino)ferrocene ((S_p)-33a)

Yield: 192 mg (0.38 mmol, 16 % based on (S_p)-27). ¹H NMR

(CDCl₃, δ): 2.11 (s, 3 H, CH₃), 3.74–3.76 (m, 1 H, C₅H₃), 3.89 (d,

2

²J_H,H= 16.3 Hz, 1 H, CH₂), 4.03 (d, J_H,H= 16.3 Hz, 1 H, CH₂),

Bis((S_p)-(2-thiodiphenylphosphino)ferrocenylmethylen)sulfane

((S_p,S_p)-32)

4.11–4.13 (m, 1 H, C₅H₃), 4.18–4.19 (m, 1 H, C₅H₃), 4.35 (s, 5 H,

C₅H₅), 6.94–6.98 (m, 1 H, C₆H₄), 7.00–7.02 (m, 2 H, C₆H₄), 7.03–

7.05 (m, 1 H, C₆H₄), 7.28–7.40 (m, 5 H, C₆H₅), 7.59–7.64 (m, 3 H,

C₆H₅), 7.82–7.86 (m, 2 H, C₆H₅). ¹³C{¹H} NMR (CDCl₃, δ): 19.4

Compound (S_p)-27 (1.0 g, 2.4 mmol) was dissolved in 50 mL of

dioxane followed by the addition of p-TsOH (1.37 g, 7.2 mmol),

sulfur (100 mg, 3.12 mmol) and MgSO₄(1 g). The reaction mixture

was heated to 90 °C and stirred for 24 h at this temperature

followed by removal of all volatiles in vacuum. Purification was

realized by column chromatography (silica, 2.5 x 12 cm column

size) using a 1:9 hexane/dichloromethane mixture (v/v) as the

eluent. After removal of all volatiles in vacuum, (S_p,S_p)-32 was

obtained as an orange solid.

2

(CH₃), 32.0 (CH₂), 68.1 (d, J_P,C= 10.4 Hz, C₅H₃), 70.8 (C₅H₅),

73.7 (d, J_P,C= 9.8 Hz, C₅H₃), 74.2 (d, J_P,C= 9.8 Hz, C₅H₃), 74.4 (d,

¹J_P,C= 57.6 Hz, C_C5H3–P), 92.1 (d, J_P,C= 12.4 Hz, C_C5H3–C), 125.4

4

(C4-C₆H₅), 126.0 (C5-C₆H₅), 128.0 (d, J_P,C= 3.9 Hz, p-C₆H₅),

2

128.2 (d, J_P,C= 12.4 Hz, o-C₆H₅), 129.5 (C3-H₆H₅), 129.8 (C6-

C₆H₄), 131.1 (d, ⁴J_P,C= 3.0 Hz, p-C₆H₅), 131.8 (d, ²J_P,C= 12.7 Hz,

o-C₆H₅), 131.9 (d, ³J_P,C= 10.6 Hz, m-C₆H₅), 133.4 (d,

1

¹J_P,C= 22.4 Hz, C_C6H5–P), 134.1 (d, J_P,C= 22.5 Hz, C_C5H6–P),

136.3 (C₆H₄), 138.5 (C2-C₆H₄). ³¹P{¹H} NMR (CDCl₃, δ): 41.8.

Yield: 0.619 mg (0.72 mmol, 90 % based on (S_p)-27). Anal. calcd

for C₄₆H₄₀Fe₂P₂S₃(862.63 g/mol): C, 64.04; H, 4.67. Found: C,

1

2

64.16; H, 4.94. Mp: 115 °C. H NMR (CDCl₃, δ): 3.72 (d, J_H,H

=

(S_p)-2-(4-Methylyphenylmethyl)-1-

13.5 Hz, 2 H, CH₂), 3.72 – 3.73 (m, 2 H, C₅H₃), 3.91(d, ²J_H,H= 13.7

Hz, 2 H, CH₂) 4.22 – 4.23 (m, 2 H, C₅H₃), 4.30 (s, 10 H, C₅H₅),

4.46 – 4.47 (m, 2 H, C₅H₃), 7.33 – 7.36 (m, 4 H, C₆H₅), 7.41 – 7.47

(m, 6 H, C₆H₅), 7.48 – 7.52 (m, 2 H, C₆H₅),7.58 – 7.62 (m, 4 H,

C₆H₅), 7.76 – 7.80 (m, 4 H, C₆H₅). ¹³C{¹H} NMR (CDCl₃, δ): 31.2

(thiodiphenylphosphino)ferrocene ((S_p)-33c)

Yield: 575 mg (1.14 mmol, 47 % based on (S_p)-27). ¹H NMR

(CDCl₃, δ): 2.20 (s, 3 H, CH₃), 3.65–3.66 (m, 1 H, C₅H₃), 3.88 (d,

2

²J_H,H= 15.1 Hz, 1 H, CH₂), 4.19 (d, J_H,H= 15.5 Hz, 1 H, CH₂),

(CH₂), 68.8 (d, J_P,C= 10.4 Hz, C₅H₃), 70.8 (C₅H₅), 73.3 (d, J_P,C

=

4.21–4.22 (m, 1 H, C₅H₃), 4.33 (s, 5 H, C₅H₅), 4.39–4.40 (m, 1 H,

1

3

9.3 Hz, C₅H₃) 73.6 (d, J_P,C= 95.1 Hz, C_C5H3–P), 74.2 (d, J_P,C

C₅H₃), 6.80 (d, J_H,H= 7.8 Hz,

2 H, H2-C₆H₄), 6.91 (d,

12.7 Hz, C₅H₃), 89.8 (d, ²J_P,C= 11.9 Hz, C_C5H3–C), 127.9 (d, ²J_P,C

³J_H,H= 7.9 Hz, 2 H, H3-C₆H₄), 7.17–7.21 (m, 2 H, C₆H₅), 7.32–

7.36 (m, 1 H, C₆H₅), 7.42–7.46 (m, 4 H, C₆H₅), 7.48–7.51 (m, 1 H,

C₆H₅), 7.77–7.81 (m, 2 H, C₅H₆). ¹³C{¹H} NMR (CDCl₃, δ): 20.9

(CH₃), 33.7 (CH₂), 68.5 (d, J_P,C= 10.4 Hz, C₅H₃), 70.7 (C₅H₅), 73.7

2

= 12.4 Hz, o-C₆H₅), 128.1 (d, J_P,C= 12.5 Hz, o-C₆H₅), 131.0 (d,

⁴J_P,C= 2.9 Hz, p-C₆H₅), 131.1 (d, ⁴J_P,C= 2.8 Hz, p-C₆H₅), 131.7 (d,

³J_C,P= 11.1 Hz, m-C₆H₅), 131.8 (d, ³J_C,P= 11.1 Hz, m-C₆H₅), 133.5

1

(d, J_P,C= 86.0 Hz, C_C6H5–P), 134.6 (d, J_P,C= 87 Hz, C_C6H5–P).

³¹P{¹H} NMR (CDCl₃, δ): 41.7. HRMS (ESI-TOF, m/z): calcd for

C₄₆H₄₀Fe₂P₂S₃+Na 885.0360, found 885.0330 [M+Na]⁺.

(d, J_P,C= 95.3 Hz, C_C5H3–P), 73.6 (d, J_P,C= 9.8 Hz, C₅H₃), 74.3

(d, J_P,C= 13.0 Hz, C₅H₃), 93.3 (d, ²J_P,C= 12.6 Hz, C_C5H3–C), 127.8

3

(d, J_P,C= 3.3 Hz, m-C₆H₅), 127.9 (d, J_P,C= 3.0 Hz, m-C₆H₅),

4

128.4 (C2-C₆H₄), 128.8 (C3-C₆H₄), 130.5 (d, J_P,C= 3.0 Hz, p-

C₆H₅), 131.0 (d, ⁴J_P,C= 2.9 Hz, p-C₆H₅), 131.9 (d, ²J_P,C= 10.6 Hz,

o-C₆H₅), 132.0 (d, ²J_P,C= 10.7 Hz, o-C₆H₅), 133.6 (d,

(S_p)-2-(2-/3-/4-Methylphenylmethyl)-1-

(thiodiphenylphosphino)ferrocene ((S_p)-33a,b,c)

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European Journal of Inorganic Chemistry

FULL PAPER

1

2

¹J_P,C= 52.2 Hz, C_C6H5–P), 134.3 (d, J_P,C= 53.0 Hz, C_C6H5–P),

⁴J_P,C= 2.9 Hz, p-C₆H₅), 131.9 (d, J_P,C= 10.7 Hz, o-C₆H₅), 132.0

134.9 (C4-C₆H₄), 137.4 (C1-C₆H₄). ³¹P{¹H} NMR (CDCl₃, δ): 42.0.

(d, J_P,C= 10.8 Hz, o-C₆H₅), 132.8 (C4-C₆H₄), 133.6 (d,

2

¹J_P,C= 60.9 Hz, C_C6H5–P), 134.3 (d, J_P,C= 61.8 Hz, C_C6H5–P),

1

157.5 (C1-C₆H₄). ³¹P{¹H} NMR (CDCl₃, δ): 42.0. HRMS (ESI-TOF,

m/z, (rel. intensity)): see (S_p)-34a.

(S_p)-2-(2-Methoxyphenylmethyl)-1-(thiodiphenylphosphino)

ferrocene ((S_p)-34a) and (S_p)-2-(4-methoxyphenylmethyl)-1-

(thiodiphenylphosphino)ferrocene ((S_p)-34c)

(S_p)-(Diphenylphosphino)-2-(2-hydroxyphenylmethyl)ferrocene

((S_p)-35)

Compound (S_p)-27 (200 mg, 0.48 mmol), p-TsOH (270 mg, 1.4

mmol) and MgSO₄(1 g) were dissolved in 20 mL of anisole. The

reaction mixture was heated to 90 °C and stirred for 24 h at this

temperature followed by removal of all volatiles in vacuum.

Purification was realized by column chromatography (silica, 2.5 x

18 cm column size) using a 3:9 hexane/dichloromethane mixture

Compound (S_p)-27 (200 mg, 0.463 mmol) and phenol (436 mg,

4.63 mmol) were dissolved in 10 mL of dichloromethane followed

by the addition of p-TsOH (264 mg, 1.53 mmol). The reaction

mixture was heated to 50 °C and stirred for 72 h at this

(v/v) for eluting (S_p)-34a followed by dichloromethane for (S_p)-34c. temperature followed by removal of all volatiles in vacuum.

Both compounds were obtained as orange solids after removal of

all volatiles in vacuum.

Purification was realized by column chromatography (silica, 2.5 x

18 cm column size) using dichloromethane as the eluent. After

removal of all volatiles, compound (S_p)-35 was obtained as an

orange solid.

(S_p)-34a: Yield: 114 mg (0.17 mmol, 36 % based on (S_p)-27). Anal.

calcd for C₃₀H₂₇FeOPS∙ 1/6 CH₂Cl₂(522.42 ∙ 1/6 84.93 g/mol): C,

1

67.53; H, 5.13. Found: C, 67.46; H, 5.44. Mp: 107 °C. H NMR

Yield: 175 mg (0.344 mmol, 74 % based on (S_p)-27). Anal. calcd

for C₂₉H₂₅FeOPS ∙ 1/3 C₆H₁₄(508.39 ∙ 1/6 86.18 g/mol): C, 69.32;

(CDCl₃, δ): 3.67–3.68 (m, 1 H, C₅H₃), 3.76 (s, 3 H, OCH₃), 3.99

(d, ²J_H,H= 15.2 Hz, 1 H, CH₂), 4.12 (d, ²J_H,H= 15.2 Hz, 1 H, CH₂),

4.17–4.19 (m, 1 H, C₅H₃), 4.32 (s, 5 H, C₅H₅), 4.40–4.41 (m, 1 H,

C₅H₃), 6.56 (td, ³J_H,H= 7.4 Hz, ⁴J_H,H= 1.0 Hz, 1 H, H4-C₆H₄), 6.74

1

H, 5.57. Found: C, 69.30; H, 5.37. Mp: 223 °C. H NMR (CDCl₃,

δ): 3.65 (dd, J = 2.4 Hz, J = 2.4 Hz, J = 1.5 Hz, 1 H, C₅H₃), 3.82

(d, ²J_H,H= 15.3 Hz, 1 H, CH₂), 4.13 (d, ²J_H,H= 15.3 Hz, 1 H, CH₂),

4.26 (s, 5 H, C₅H₅), 4.28–4.30 (m, 1 H, C₅H₃), 4.55 (ddd, J = 2.3

3

4

(dd, J_H,H= 8.2 Hz, J_H,H= 1.1 Hz, 1 H, H6-C₆H₄), 6.96 (dd,

³J_H,H= 7.4 Hz, J_H,H= 1.6 Hz,

1

H, H3-C₆H₄), 7.04 (td,

Hz, J = 2.3 Hz, J = 1.6 Hz, 1 H, C₅H₃), 6.59 (dd, J_H,H= 8.1 Hz,

4

3

³J_H,H= 8.0 Hz, J_H,H= 1.7 Hz, 1 H, H5-C₆H₄), 7.26–7.29 (m, 2 H,

C₆H₅), 7.36–7.40 (m, 1 H, C₆H₅), 7.43–7.52 (m, 3 H, C₆H₅), 7.55–

7.59 (m, 2 H, C₆H₅), 7.80–7.85 (m, 2 H, C₆H₅). ¹³C{¹H} NMR

⁴J_H,H= 1.1 Hz, 1 H, C₆H₄-H3), 6.71 (td, ³J_H,H= 7.4 Hz, ⁴J_H,H= 1.2

Hz, 1 H, C₆H₄-H5), 6.89 (s, 1 H, OH), 6.92 (td, ³J_H,H= 7.9 Hz, ⁴J_H,H

= 1.7 Hz, 1 H, C₆H₄-H4), 7.02 (dd, ³J_H,H= 7.6 Hz, ⁴J_H,H= 1.6 Hz,

1 H, C₆H₄-H6), 7.18–7.21 (m, 2 H, Ph), 7.30–7.34 (m, 1 H, Ph),

7.36–7.41 (m, 2 H, Ph), 7.45–7.49 (m, 2 H, Ph), 7.51–7.55 (m, 1

H, Ph), 7.76–7.80 (m, 2 H, Ph). ¹³C{¹H} NMR (CDCl₃, δ): 27.4

4

3

(CDCl₃, δ): 28.5 (CH₂), 55.1 (OCH₃), 58.3 (d, J_P,C= 10.6 Hz,

C₅H₃), 70.7 (C₅H₅), 73.7 (d, J_P,C= 95.6 Hz, C_C5H3–P), 73.9 (d,

1

J_P,C= 13.1 Hz, C₅H₃), 74.1 (d, J_P,C= 9.8 Hz, C₅H₃), 92.7 (d,

²J_P,C= 12.3 Hz, C_C5H3–C), 110.0 (C6-C₆H₄), 119.9 (C4-C₆H₄),

(CH₂), 69.0 (d, J_C,P= 10.5 Hz, C₅H₃), 70.8 (C₅H₅), 73.0 (d, ¹J_C,P

95.8 Hz, C_C5H3–P), 73.6 (d, J_C,P= 9.9 Hz, C₅H₃), 74.0 (d, J_C,P

=

2

127.0 (C5-C₆H₄), 126.8 (d, J_P,C= 8.0 Hz, o-C₆H₅), 127.9 (d,

²J_P,C= 8.0 Hz, o-C₆H₅), 129.0 (C2-C₆H₄), 130.8 (C3-C₆H₄), 130.8

(d, ⁴J_P,C= 2.9 Hz, p-C₆H₅), 131.0 (d, ⁴J_P,C= 2.9 Hz, p-C₆H₅), 132.0

12.9 Hz, C₅H₃), 92.7 (d, ²J_C,P= 12.7 Hz, C_C5H3–CH₂), 117.2 (C₆H₄-

C3), 120.1 (C₆H₄-C5), 126.6 (C₆H₄–C1), 127.5 (C₆H₄-C4), 128.0

(d, ³J_C,P= 12.7 Hz, C3/5-Ph), 128.1 (d, ³J_C,P= 12.5 Hz, C3/5-Ph),

130.1 (C₆H₄-C6), 131.2 (d, ⁴J_C,P= 3.0 Hz, C4-Ph), 131.5 (d, ⁴J_C,P

3

(d, J_P,C= 6.4 Hz, m-C₆H₅), 132.1 (d, J_P,C= 6.6 Hz, m-C₆H₅),

1

133.8 (d, J_P,C= 75.5 Hz, C_C6H5–P), 134.5 (d, J_P,C= 76.1 Hz,

C_C6H5–P), 157.2 (C1-C₆H₄). ³¹P{¹H} NMR (CDCl₃, δ): 42.2. HRMS

(ESI-TOF, m/z): calcd for C₃₀H₂₇FeOPS 522.0865, found

522.0845 [M]⁺.

2

= 2.9 Hz, C4-Ph), 131.7 (d, J_C,P= 10.8 Hz, C2/6-Ph), 132.1 (d,

²J_C,P= 10.9 Hz, C2/6-Ph), 132.4 (d, ¹J_C,P= 86.8 Hz, C1-Ph), 133.5

(d, ¹J_C,P= 86.9 Hz, C1-Ph), 153.2 (C2–OH). ³¹P{¹H} NMR (CDCl₃,

δ): 42.6. IR data (KBr, ν/cm^–1): 3403 m (v OH), 3069 w, 3049 w,

2955 m, 2919 s, 2848 m, 1710 w, 1580 m, 1484 s, 1432 s, 1260

w, 1208 m, 1166 m, 1101 s (v C–O), 1043 w, 760 m, 715 s, 692

s, 643 m. HRMS (ESI-TOF, m/z): calcd for C₂₉H₂₅FeOPS+H

509.0786, found 509.0743 [M+H]⁺.

(S_p)-34c: Yield: 117 mg (0.18 mmol, 37 % based on (S_p)-27). Anal.

calcd for C₃₀H₂₇FeOPS (522.42 g/mol): C, 68.97; H, 5.21. Found:

C, 68.62; H, 5.21. Mp: 196 °C. ¹H NMR (CDCl₃, δ): 3.64–3.65 (m,

2

1 H, C₅H₃), 3.69 (s, OCH₃), 3.83 (d, J_H,H= 15.1 Hz, 1 H, CH₂),

4.23 (d, ²J_H,H= 14.9 Hz, 1 H, CH₂), 4.21–4.23 (m, 1 H, C₅H₃), 4.33

(s, 5 H, C₅H₅), 4.40–4.41 (m, 1 H, C₅H₃), 6.52 (d, ³J_H,H= 8.7 Hz, 2

H, H2-C₆H₄), 6.95 (d, ³J_H,H= 8.6 Hz, 2 H, H3-C₆H₄), 7.17–7.21 (m,

2 H, C₆H₅), 7.31–7.35 (m, 1 H, C₆H₅), 7.40–7.46 (m, 4 H, C₆H₅),

7.47–7.51 (m, 1 H, C₆H₅), 7.76–7.82 (m, 2 H, C₆H₅). ¹³C{¹H} NMR

(S_p)-2-(3-Hydroxy-2,4,6-trimethylphenylmethyl)-1-thiodiphenyl-

phosphino)ferrocene (S_p)-36)

Compound (S_p)-27 (150 mg, 0.347 mmol) and 2,4,6-

trimethylphenol (473 mg, 3.47 mmol) were dissolved in 10 mL of

dichloromethane followed by the addition of p-TsOH (178 mg,

1.04 mmol). The reaction mixture was heated to 50 °C and stirred

for 72 h at this temperature followed by removal of all volatiles in

vacuum. Purification was realized by column chromatography

(silica, 2.5 x 18 cm column size) using dichloromethane as the

3

(CDCl₃, δ): 33.2 (CH₂), 55.1 (OCH₃), 68.5 (d, J_P,C= 10.5 Hz,

1

C₅H₃), 70.7 (C₅H₅), 73.6 (d, J_P,C= 95.4 Hz, C_C5H3–P), 73.6 (d,

2

³J_P,C= 9.7 Hz, C₅H₃), 74.4 (d, J_P,C= 12.8 Hz, C₅H₃), 93.5 (d,

²J_P,C= 12.5 Hz, C_C5H3–C), 113.2 (C2-C₆H₄), 127.8 (d,

3

³J_P,C= 4.5 Hz, m-C₆H₅), 127.9 (d, J_P,C= 4.3 Hz, m-C₆H₅), 129.9

4

(C3-C₆H₄), 130.7 (d, J_P,C= 2.9 Hz, p-C₆H₅), 131.1 (d,

10.1002/ejic.201700645

European Journal of Inorganic Chemistry

FULL PAPER

eluent. After removal of all volatiles, compound (S_p)-36 was

obtained as an orange solid.

C_C5H3–CH₂), 121.4 (C3_C6H3), 126.7 (C5/6_C6H3), 127.6 (C5/6_C6H3),

2

128.18 (d, J_C,P= 12.5 Hz, C3/5_C6H5), 128.22 (d, J_C,P= 12.5 Hz,

C3/5_C6H5), 131.55 (d, ⁴J_C,P= 3.2 Hz, C4_C6H5), 131.57 (d, ⁴J_C,P= 3.2

Hz, C4_C6H5), 131.9 (d, ³J_C,P= 10.6 Hz, C2/6_C6H5), 132.0 (d, ³J_C,P

=

Yield: 173 mg (0.314 mmol, 90 % based on (S_p)-27). Anal. calcd

for C₃₂H₃₁FeOPS ∙ C₆H₁₄(550.47 ∙ 86.18 g/mol): C, 69.93; H, 6.95.

Found: C, 69.71; H, 6.92. ¹H NMR (CDCl₃, δ): 1.98 (s, 3 H, Mes-

CH₃-C2), 2.02 (s, 3 H, Mes-CH₃-C6), 2.19 (s, 3 H, Mes-CH₃-C4),

3.30 (d, ²J_H,H= 17.2 Hz, 1H, CH₂), 3.81 (ddd, J = 2.5 Hz, J = 2.0

Hz, J = 1.5 Hz, 1 H, C₅H₃), 3.91 (dd, J = 3.6 Hz, J = 1.9 Hz, 1 H,

C₅H₃), 4.11 (ddd, J = 2.5 Hz, J = 2.5 Hz, J = 1.6 Hz, 1 H, C₅H₃),

4.30 (s, 5 H, C₅H₅), 4.32 (d, ²J_H,H= 17.0 Hz, 1 H, CH₂), 4.41 (s, 1

H, OH), 6.75 (s, 1 H, Mes–H), 7.40–7.44 (m, 2 H, Ph), 7.46–7.53

(m, 4 H, Ph), 7.80–7.84 (m, 2 H, Ph), 7.89–7.94 (m, 2 H, Ph).

¹³C{¹H} NMR (CDCl₃, δ): 12.5 (Mes-CH₃-C2), 15.8 (Mes-CH₃-C4),

19.8 (Mes-CH₃-C6), 29.1 (CH₂), 67.6 (d, J_C,P= 10.3 Hz, C₅H₃),

70.9 (C₅H₅), 73.3 (d, J_C,P= 10.0 Hz, C₅H₃), 73.4 (d, J_C,P= 12.8 Hz,

1

10.9 Hz, C2/6_C6H5), 132.7 (d, J_C,P= 86.5 Hz, C1_C6H5), 134.1 (d,

¹J_C,P= 87.2 Hz, C1_C6H5), 143.6 (C2/4_C6H3), 144.1 (C2/4_C6H3), 146.9

(C1_C6H3). ³¹P{¹H} NMR (CDCl₃, δ): 40.8. IR data (KBr, ν/cm^–1):

3078 w, 3065 w, 2958 w, 2922 s, 2854 m, 1737 m, 1585 m, 1520

s (ν_asNO₂), 1436 m, 1345 s (ν_sNO₂), 1169 m, 1101 w, 1042 m,

835 m, 712 s, 692 m, 645 m (ν P=S). HRMS (ESI-TOF, m/z): calcd

for C₂₉H₂₃FeN₂O₄PS₂614.0181, found 614.0193 [M]⁺.

Bis((S_p)-(2-diphenylphosphino)ferrocenylmethyl)sulfane ((S_p,S_p)-

38)

Compound (S_p,S_p)-32 (860 mg, 1.08 mmol) was dissolved in 50

mL of chlorobenzene followed by the dropwise addition of

P(NMe₂)₃(1.8 mL, 10 mmol). The reaction mixture was heated to

130 °C and stirred for 18 h at this temperature and then allowed

to cool to ambient temperature. Water (10 mL) was carefully

added. This mixture was poured into water (200 mL) and

extracted with dichloromethane (3 x 50 mL). The combined

organic extracts were dried over MgSO₄followed by removal of

all volatiles in vacuum. Purification was realized by column

C₅H₃), 74.0 (d, ¹J_C,P= 96.0 Hz, C_C5H3–P), 93.0 (d, ²J_C,P= 12.5 Hz,

3

C_C5H3–CH₂), 120.3 (Mes-C4), 122.1 (Mes-C2), 128.1 (d, J_C,P

=

12.4 Hz, m-Ph), 128.26 (d, ³J_C,P= 12.3 Hz, m-Ph), 128.33 (Mes-

C6), 129.6 (Mes-C5), 131.2 (d, J_C,P= 3.0 Hz, p-Ph), 131.3 (d,

⁴J_C,P= 2.9 Hz, p-Ph), 132.0 (d, J_C,P= 10.7 Hz, o-Ph), 132.3 (d,

4

2

²J_C,P= 10.5 Hz, o-Ph), 133.5 (d, ¹J_C,P= 85.9 Hz, C_Ph–P), 133.8 (d,

¹J_C,P= 85.0 Hz, C_Ph–P), 135.9 (Mes-C1), 150.1 (Mes–OH). ³¹P{¹H}

NMR (CDCl₃, δ): 41.2. HRMS (ESI-TOF, m/z): calcd for

C₃₂H₃₁FeOPS 549.1194, found 549.1050 [M]⁺; calcd for

C₃₂H₃₁FeOPS+H 550.1178, found 550.1114 [M+H]⁺.

chromatography (silica, 2.5

x 16 cm column size) using

dichloromethane as the eluent. Compound (S_p,S_p)-38 was

recrystallized from boiling hexane and obtained as an orange

solid after removal of all volatiles.

(S_p)-2-((2,4-Dinitrophenyl)thiomethyl)-1-(thiodiphenyl-

phosphino)ferrocene ((S_p)-37)

Yield: 405 mg (0.51 mmol, 51 % based on (S_p,S_p)-32). Anal. calcd

Compound (S_p)-27 (240 mg, 0.555 mmol), 1-fluoro-2,4-

dinitrobenzene (310 mg, 1.67 mmol) and K₂CO₃(384 mg, 2.78

mmol) were dissolved in 20 mL of DMF, whereby the color

immediately darkened. The reaction mixture was heated to 40 °C

and stirring was continued for 18 h at this temperature. After

cooling the reaction mixture to ambient temperature, it was diluted

with 50 mL of diethyl ether and washed with acidified (HCl) brine

(50 mL). After extraction with diethyl ether (3 x 50 mL) all organic

extracts were combined and dried over MgSO₄followed by

removal of all volatiles in vacuum. Purification was realized by

column chromatography (silica, 2.5 x 18 cm column size) using a

1:1 dichloromethane/ethyl acetate mixture (v/v) as the eluent.

After removal of all volatiles, compound (S_p)-37 was obtained as

an orange solid.

for C₄₆H₄₀Fe₂P₂S (798.51 g/mol): C, 69.19; H, 5.05. Found: C,

1

2

69.62; H, 5.44. Mp: 98 °C. H NMR (CDCl₃, δ): 3.60 (dd, J_H,H

=

13.1 Hz, ⁴J_H,P= 1.8 Hz, 2 H, CH₂), 3.64 (d, ²J_H,H= 13.1 Hz, 2 H,

CH₂), 3.73–3.74 (m, 2 H, C₅H₃), 3.91 (s, 10 H, C₅H₅), 4.21–4.22

(m, 2 H, C₅H₃), 4.31–4.32 (m, 2 H, C₅H₃), 7.16–7.19 (m, 4 H, C₆H₅),

7.22–7.25 (m, 6 H, C₆H₅), 7.36–7.38 (m, 6 H, C₆H₅), 7.53–7.57 (m,

4 H, C₆H₅). ¹³C{¹H} NMR (CDCl₃, δ): 32.0 (d, ³J_P,C= 11.7 Hz, CH₂),

69.2 (C₅H₃), 69.7 (C₅H₅), 71.1 (d, J_P,C= 3.9 Hz, C₅H₃), 71.3 (d,

1

J_P,C= 3.9 Hz, C₅H₃), 75.5 (d, J_P,C= 7.8 Hz, C_C5H3–P), 90.9 (d,

²J_P,C= 25.9 Hz, C_C5H3–C), 127.6 (p-C₆H₅), 127.9 (d, ³J_P,C= 5.9 Hz,

m-C₆H₅), 128.0 (d, ³J_P,C= 8.0 Hz, m-C₆H₅), 129.0 (p-C₆H₅), 132.2

2

(d, J_P,C= 17.6 Hz, o-C₆H₅), 135.1 (d, J_P,C= 21.4 Hz, o-C₆H₅),

137.7 (d, ¹J_P,C= 8.7 Hz, C_C6H5–P), 140.0 (d, ¹J_P,C= 9.4 Hz, C_C6H5

–

P). ³¹P{¹H} NMR (CDCl₃, δ): –23.7. HRMS (ESI-TOF, m/z): calcd

for C₄₆H₄₀FePS+H 799.1099, found 799.1120 [M+H]⁺.

Yield: 95 mg (0.155 mmol, 56 % based on (S_p)-27). Anal. calcd

for C₂₉H₂₃FeN₂O₄PS₂∙ 1/2 C₆H₁₄(614.45 ∙ 1/2 86.18 g/mol): C,

58.45; H, 4.60; N, 4.26. Found: C, 58.26; H, 4.27; N, 4.45. Mp:

245 °C (explosive decomp.). ¹H NMR (CDCl₃, δ): 3.84–3.86 (m, 1

H, C₅H₃), 4.39–4.43 (m, 7 H, CH₂, C₅H₅, C₅H₃), 4.66–4.68 (m, 1

H, C₅H₃), 4.96 (d, ²J_H,H= 12.4 Hz, CH₂), 7.30–7.34 (m, 2 H, C₆H₅),

7.42–7.45 (m, 1 H, C₆H₅),7.47–7.51 (m, 2 H, C₆H₅), 7.53–7.59 (m,

(S_p)-(Diphenylphosphino)-2-(2-methoxyphenylmethyl)ferrocene

((S_p)-39)

Compound (S_p)-34a (192 mg, 0.29 mmol) was dissolved in 20 mL

of chlorobenzene followed by the addition of P(NMe₂)₃(0.6 mL,

2.88 mmol). The reaction mixture was heated to 130 °C and

stirred for 18 h at this temperature and then allowed to cool to

ambient temperature. Water (5 mL) was carefully added. The

mixture was poured into water (200 mL) and extracted with

dichloromethane (3 x 40 mL). The combined organic extracts

were dried over MgSO₄followed by removal of all volatiles in

4 H, C₆H₅, C₆H₃), 7.81–7.85 (m, 2 H, C₆H₅, C₆H₃), 8.21 (dd, J_H,H

=

9.0 Hz, J_H,H= 2.5 Hz, C₆H₃), 8.94 (d, JH,H = 2.5 Hz, H3_C6H3).

¹³C{¹H} NMR (CDCl₃, δ): 32.0 (CH₂), 69.8 (d, J_C,P= 10.1 Hz, C₅H₃),

71.3 (C₅H₅), 74.0 (d, J_C,P= 8.9 Hz, C₅H₃), 74.8 (d, ¹J_C,P= 94.1 Hz,

C_C5H3–P), 75.0 (d, J_C,P= 11.8 Hz, C₅H₃), 85.2 (d, ²J_C,P= 11.9 Hz,

10.1002/ejic.201700645

European Journal of Inorganic Chemistry

FULL PAPER

2

vacuum. Purification was realized by column chromatography

(silica, 2.5 x 16 cm column size) using dichloromethane as the

eluent. Compound (S_p)-39 was recrystallized from boiling hexane

and obtained as an orange solid after removal of all volatiles.

29.3 (CH₂), 34.34 (d, J_C,P= 5.6 Hz, NMe₂), 34.35 (d, J_C,P= 5.4

Hz, NMe₂), 67.71 (C₅H₃), 70.9 (C₅H₅), 71.0 (C₅H₅), 73.2 (d, J_C,P

9.8 Hz, C₅H₃), 73.5 (d, J_C,P= 12.9 Hz, C₅H₃), 74.0 (d, ¹J_C,P= 95.0

Hz, C–P), 92.4 (d, 2JC,P = 12.2 Hz, C_C5H3–CH₂), 127.4 (^qC), 127.8

=

(^qC), 128.1 (d, J_C,P= 12.5 Hz, m-Ph), 128.3 (d, J_C,P= 12.3 Hz,

m-Ph), 128.9 (^qC), 129.8 (^qC), 130.33 (CH), 130.34 (CH), 131.18

(CH), 131.20 (CH), 131.34 (CH), 131.37 (CH), 131.9 (CH), 132.0

(CH), 132.2 (CH), 132.3 (CH), 133.0 (^qC), 133.4 (^qC), 133.7 (^qC),

134.06 (^qC), 134.07 (^qC), 134.1 (^qC), 136.37 (^qC), 136.40 (^qC),

145.5 (d, ²J_C,P= 9.5 Hz, C–O–P). ³¹P{¹H} NMR (CDCl₃, δ): 12.25

(¹J_P,H= 646 Hz, PHO₂N), 12.29 (¹J_P,H= 646 Hz, PHO₂N), 41.13

(P=S), 41.15 (P=S).

3

Yield: 145 mg (0.23 mmol, 79 % based on (S_p)-34a). Anal. calcd

for C₃₀H₂₇FeOP∙1.5 C₅H₁₂(490.35 ∙ 1.5 72.15 g/mol): C, 73.29; H,

1

7.38. Found: C, 73.71; H, 7.16. Mp: 104 °C. H NMR (CDCl₃, δ):

2

3.71 (s, 3 H, OCH₃), 3.72–3.73 (m, 1 H, C₅H₃), 3.86 (d, J_H,H

=

15.1 Hz, 1 H, CH₂), 3.93 (dd, ²J_H,H= 15.1 Hz, ⁴J_H,P= 2.1 Hz, 1 H,

CH₂), 4.01 (s, 5 H, C₅H₅), 4.21–4.22 (m, 1 H, C₅H₃), 4.42–4.43 (m,

1 H, C₅H₃), 6.61 (td, ³J_H,H= 7.4 Hz, ⁴J_H,H= 1.0 Hz, 1 H, H4-C₆H₄),

3

6.67–6.70 (m,

1

H, H6-C₆H₄), 6.92 (dd, J_H,H= 7.4 Hz,

⁴J_H,H= 1.6 Hz, 1 H, H3-C₆H₄), 7.02–7.07 (m, 3 H, H5-C₆H₄, C₆H₅),

7.09–7.16 (m, 3 H, C₆H₅), 7.37–7.40 (m, 3 H, C₆H₅), 7.57–7.61 (m,

2 H, C₆H₅). ¹³C{¹H} NMR (CDCl₃, δ): 28.6 (d, ³J_C,P= 10.1 Hz, CH₂),

54.9 (OCH₃), 68.9 (C₅H₃), 69.7 (C₅H₅), 70.6 (d, J_P,C= 4.1 Hz,

N-([1,1'-Binaphthalen]-2-yl)benzamide (41l)

The title compound was obtained from 2-amino-1-

bromonaphtalene (222 mg) and 1-naphthylboronic acid (258 mg)

by using the general procedure for Suzuki-Miyaura C,C cross-

coupling reactions (Supporting Information). The conversion of

the formed amine into amide 41l was performed similar to a

literature reported protocol. ⁸⁷Thus, the whole sample was

transferred into a Schlenk tube by using dichloromethane (10 mL)

and diluted with 5 mL of THF. Benzoyl chloride (0.15 mL, 1.3

mmol) was added in a single portion followed by triethylamine

(0.28 mL, 1.3 mmol). The reaction mixture was stirred at 65 °C for

6 h and afterward allowed to cool to ambient temperature. The

solution was poured into water (50 mL) and extracted with diethyl

ether (3 x 50 mL). The combined organic layers were dried over

MgSO₄followed by removal of all volatiles in vacuum. Purification

was realized by column chromatography (silica, 4 x 23 cm column

size) using a hexane/diethyl ehter mixture (v/v) as the eluent. The

product is eluted as the 3^rdfraction, after 1,1’-binaphthyl as the 1^st,

and a fluorescent fraction as the 2^ndfraction. After removal of all

volatiles 41l was obtained as a colorless oil.

C₅H₃), 72.1 (d, J_P,C= 4.0 Hz, C₅H₃), 75.3 (d, ¹J_P,C= 6.7 Hz, C_C5H3

–

2

P), 93.8 (d, J_P,C= 26.3 Hz, C_C5H3–C), 109.8 (C6-C₆H₄), 119.9

(C4-C₆H₄), 126.9 (C5-C₆H₄), 127.4 (C3-C₆H₄), 127.6 (d,

3

³J_P,C= 6.0 Hz, m-C₆H₅), 128.0 (d, J_P,C= 7.9 Hz, m-C₆H₅), 128.9

(p-C₆H₅), 129.4 (C2-C₆H₄), 130.3 (d, ⁴J_P,C= 1.1 Hz, p-C₆H₅), 132.3

2

(d, J_P,C= 18.0 Hz, o-C₆H₅), 135.2 (d, J_P,C= 21.1 Hz, o-C₆H₅),

138.0 (d, ¹J_P,C= 8.5 Hz, C_C6H5–P), 139.8 (d, ¹J_P,C= 9.6 Hz, C_C6H5

P), 159.9 (C1-C₆H₄). ³¹P{¹H} NMR (CDCl₃, δ): –22.5. HRMS (ESI-

TOF, m/z): calcd for C₃₀H₂₇FeOP 490.1144, found 490.1195 [M]⁺.

–

3-(2-(Thiodiphenylphosphino)ferrocenylmethyl)-2,4,6-

trimethylphenyl-N,N-dimethylphosphonamidate (S_p)-40 and (S_p)-

40a

Compound (S_p)-36 (162 mg, 0.294 mmol) was dissolved in 20 mL

of toluene followed by the addition of P(NMe₂)₃(0.27 mL, 1.3

mmol). The reaction mixture was refluxed for 18 h and then

allowed to cool to ambient temperature. All volatiles were

removed in vacuum. Purification was realized by column

Yield: 279 mg (0.747 mmol, 75 % based on 2-amino-1-

bromonaphthalene). Anal. calcd for C₂₇H₁₉NO∙1.5 H₂O (373.45 ∙

1.5 18.02 g/mol): C, 80.98; H, 5.54; N, 3.50. Found: C, 80.82; H,

5.06; N, 3.52. ¹H NMR (CDCl₃, δ): 7.14–7.16 (m, 2 H), 7.19–7.23

(m, 3 H), 7.28 (ddd, ³J_H,H= 8.4 Hz, ³J_H,H= 6.7 Hz, J_H,H= 1.3 Hz, 1

chromatography (silica, 2.5

x 16 cm column size) using

dichloromethane as the eluent. After removal of all volatiles,

compound (S_p)-40 was obtained as a yellow solid as a 1:1 mixture

of two diastereomers. Dissolving in boiling dichloromethane and

slowly cooling the solution to ambient temperature gave single

crystals of (S_p)-40a, suitable for single crystal X-ray diffraction

analysis. The compound decomposed rapidly in solution.

3

H), 7.33–7.39 (m, 3 H), 7.43 (ddd, J_H,H= 8.0 Hz, ³J_H,H= 6.7 Hz,

J_H,H= 1.2 Hz, 1 H), 7.54 (ddd, ³J_H,H= 8.1 Hz, J_H,H= 4.0 Hz, J_H,H

=

0.8 Hz, 1 H), 7.56 (dd, ³J_H,H= 6.9 Hz, J_H,H= 1.2 Hz, 1 H), 7.65 (s,

br, 1 H, NH), 7.70 (dd, ³J_H,H= 8.2 Hz, ³J_H,H= 7.0 Hz, 1 H), 7.94 (d,

³J_H,H= 8.2 Hz, 1 H), 8.02 (d, ³J_H,H= 8.3 Hz, 1 H), 8.06 (d, ³J_H,H

=

Yield: 66 mg (0.103 mmol, 35 % based on (S_p)-36). ¹H NMR

(CDCl₃, δ): 2.04 (s, 3 H, Mes-CH3-C2/6), 2.05 (s, 3 H, Mes-CH3-

C2/6), 2.06 (s, 3 H, Mes-CH3-C2/6), 2.07 (s, 3 H, Mes-CH3-C2/6),

2.28 (s, 6 H, Mes-CH3-C4), 2.756 (d, ³J_H,P= 11.0 Hz, 6 H, NMe₂),

7.0 Hz, 1 H), 8.07 (d, ³J_H,H= 6.3 Hz, 1 H), 8.84 (d, ³J_H,H= 9.0 Hz,

1 H). ¹³C{¹H} NMR (CDCl₃, δ): 120.1 (CH), 124.9 (CH), 125.0 (^qC),

125.6 (CH), 125.9 (CH), 126.0 (CH), 126.5 (CH), 126.6 (CH),

126.7 (CH), 127.2 (CH), 128.0 (CH), 128.6 (CH), 128.6 (CH),

129.0 (CH), 129.1 (CH), 129.2 (CH), 130.9 (^qC), 131.5 (CH),

132.3 (^qC), 133.0 (^qC), 133.2 (^qC), 134.1 (^qC), 134.2 (^qC), 134.7

(^qC), 165.0 (C=O). HRMS (ESI-TOF, m/z): calcd for C₂₇H₁₉NO+H

374.1539, found 374.1541 [M+H]⁺. HPLC (Chiralcel OD–H, flow

rate 0.5 mL min^–1, hexane/i-PrOH (98:2)): 44.7, 58.1 min. IR data

(KBr, ν/cm^–1): 3412 m (NH), 3052 w, 2919 m, 2851 w, 1673 s,

1617 w, 1595 m, 1497 s, 1484 s, 1426 m, 1283 s, 780 m, 708 m.

3

2.760 (d, J_H,P= 11.0 Hz, 6 H, NMe₂), 3.26 (d, ²J_H,H= 17.1 Hz, 1

2

H, CH₂), 3.28 (d, J_H,H= 17.2 Hz, 1 H, CH₂), 3.81–3.83 (m, 2 H,

C₅H₃), 3.89–3.91 (m, 2 H, C₅H₃), 4.11–4.13 (m, 2 H, C₅H₃), 4.29

(s, 5 H, C₅H₅), 4.30 (s, 5 H, C₅H₅), 4.33 (d, ²J_H,H= 17.3 Hz, 1 H,

CH₂), 4.34 (d, ²J_H,H= 17.2 Hz, 1 H, CH₂), 6.82 (s, 2 H, Mes-H5),

1

7.02 (d, J_H,P= 646.1 Hz, 1 H, P–H), 7.04 (d, ¹J_H,P= 646.2 Hz, 1

H, P–H), 7.40–7.43 (m, 4 H, Ph), 7.47–7.54 (m, 8 H, Ph), 7.78–

7.83 (m, 4 H, Ph), 7.89–7.93 (m, 4 H, Ph). ¹³C{¹H} NMR (CDCl₃,

δ): 14.26 (CH₃), 14.28 (CH₃), 17.3 (CH₃), 19.90 (CH₃), 19.92 (CH₃),

10.1002/ejic.201700645

European Journal of Inorganic Chemistry

FULL PAPER

Acknowledgements

Keywords: Ferrocene • Phosphate • Azine • Thioether • Suzuki-

Miyaura Reaction • Imine

M. K. thanks the Fonds der Chemischen Industrie for a Ph.D.

Chemiefonds fellowship. We thank Dipl. Chem. Steve W. Lehrich

for performing the in situ NIR/UV-Vis measurements.

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Entry for the Table of Contents

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Acidic treatment of planar-chiral

ferrocenylmethanols resulted in the

formation of α-ferrocenyl carbo

cations, which underwent electrophilic

aromatic substitution reactions with

electron-rich aromatics or could be

sulfurized by the thiophosphinyl group

by an intermolecular process,

Ferrocenylmethanols

Marcus Korb, Julia Marholdt, Heinrich

Lang*

Page No. – Page No.

(Planar-Chiral) Ferrocenylmethanols:

From Anionic Homo Phospho-Fries

Rearrangements to α-Ferrocenyl

Carbenium Ions

resulting in thio ethers.

Article Doi

(Planar-Chiral) Ferrocenylmethanols: From Anionic Homo Phospho-Fries Rearrangements to α-Ferrocenyl Carbenium Ions

DOI: 10.1002/ejic.201700645

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