Chiral "basket handle" binaphthyl porphyrins: Synthesis, catalytic epoxidation and NMR conformational studies

Journal of Porphyrins and Phthalocyanines

J. Porphyrins Phthalocyanines 2010; 14: 646–659

DOI: 10.1142/S1088424610002483

Published at http://www.worldscinet.com/jpp/

Chiral “basket handle” binaphthyl porphyrins: synthesis,

catalytic epoxidation and NMR conformational studies

Eric Rose*^a◊, Emma Gallo^b◊, Nicolas Raoul^a, Léa Bouché^a, Ariane Pille^a,

Alessandro Caselli^band Olivier Lequin*^c

^aUniversité Pierre et Marie Curie, UPMC Univ Paris 06, IPCM, UMR CNRS 7201, Laboratoire de Synthèse

Organique et Organométallique, Case 181, 4 place Jussieu, F-75252 Paris Cedex 05, France

^bDipartimento di Chimica Inorganica, Metallorganica e Analitica “Lamberto Malatesta”, Università di Milano,

and ISTM-CNR, Via Venezian 21, 20133 Milano, Italy

^cUniversité Pierre et Marie Curie, UPMC Univ Paris 06, Laboratoire des Biomolécules, UMR CNRS 7203,

Case 182, 4 place Jussieu, F-75252 Paris Cedex 05, France

Received 21 May 2010

Accepted 29 June 2010

ABSTRACT:Three“baskethandle”porphyrinshavebeenpreparedbycondensationoftetrakis-(α,β,α,β-

2-aminophenyl)porphyrin atropoisomer with 1,1′-binaphthyl, 2,2′-dimethoxy, -3,3′-dicarbonylchloride,

-3,3′-diacetylchloride and -3,3′-dipropanoylchloride. The epoxidation of styrene with the three iron

catalysts, obtained after metalation of the free porphyrins, occurs with good yields and moderate ee

up to 54%. These porphyrins showed unexpected conformational differences, as revealed by NMR

spectroscopy. In particular, variable temperature NMR studies showed that the methoxy group in one of

them undergoes intermediate conformational exchange on the ¹H NMR time scale at room temperature.

Lowering the temperature to -50 °C revealed the presence of four states in slow exchange on the NMR

time scale. These results evidence a dynamic conformational equilibrium of the binaphthyl handles that

adopt different, asymmetric positions with respect to the porphyrin plane.

KEYWORDS:chiralporphyrin, NMR, conformationalexchange, binaphthylporphyrin, enantioselective

epoxidation.

porphyrins have appeared to be interesting chiral por-

phyrins [9] since the pioneering work of Groves et al. in

1983 [10], who ﬁrst reported the synthesis of 1 (Fig. 1),

a compound still of interest. Collman, Rose et al. later

developed the synthesis of a chiral porphyrin ααββC₁for

the enantioselective epoxidation of oleﬁns by conden-

INTRODUCTION

Previous studies have shown that synthetic porphy-

rins can be excellent structural and functional analogs of

the active sites of hemoproteins. For instance, efﬁcient

models of myoglobin Mb [1] and cytochrome c oxidase

CcO [2] have been described. For enantioselective reac-

tions such as epoxidation [3], cyclopropanation [4],

aziridination [5], amination [6] and functionalization

of non-activated C-H bonds [7], prodigious effort has

sation of the tetrakis-ααββ-(2-aminophenyl)porphyrin

atropoisomer TAPPH₂with (R)-2,2′-dimethoxy,-3,3′-

dichlorocarbonyl-1,1′-binaphthyl BN₁(Fig. 2) [11].

After metalation with FeCl₂, FeααββC₁used for the

been devoted to obtain catalysts using the rigid core of a

epoxidation of styrene, as an example [11], gave the (S)

porphyrin and judicious functionalization of the periph-

styrene epoxide in 95% yield and 83% ee and turnover

ery of the macrocycle [8]. In this context, binaphthyl

up to 5500 while maintaining a reasonable ee of 75% at

a rate of 40 turnovers/min. An oxidative modiﬁcation of

the catalyst is observed at the beginning of the reaction

^SPP full member in good standing

via a suggested oxidative demethylation to form a qui-

none type catalyst 2 (Fig. 3).

*Correspondence to: Eric Rose, eric.rose@upmc.fr and Olivier

Lequin, olivier.lequin@upmc.fr

ChIral “baSket hanDle” bInaPhthyl POrPhyrInS

647

Ar

N

proximal

distal

M

Ar

Ar =

N

OMe

CO₂Me

OMe

_n-1(CH₂)

Ar

1

αβαβ

(CH₂)_n-1

CO

OC

OMe

HN

MeO

NH

Fig. 1. Groves binaphthyl porphyrin

N

4'

5'

8'

N

M

N

(CH₂)_n-1-COCl

N

(CH₂)_n-1-CONHPh

6'

7'

R = OMe

HN

OMe

CO

_n-1(CH₂)

HN

CO

R

(CH₂)_n-1

(CH₂)_n-1-COCl

(CH₂)_n-1-CONHPh

BN_nn = 1-3

BINAP_nn = 1-3

Fig. 2. Binaphthyl derivatives

O

M=Fe Feα²β²C_nn = 1-3

M=Co Coα²β²C_n

Fig. 4. Metallo ααββC_nporphyrins

R

O

but of course the intermediates which involve a metal oxo

and a metallocarbene double bond cannot be compared.

We describe herein the preparation of three porphyrins

αβαβC_nobtained by condensation of binaphthyl handles

BN_n(n = 1–3) with the αβαβ atropoisomer of tetrakis-

R

OC

NH

CO

HN

CO

HN

6

HN

3

4

N

Fe

N

5

1

(2-aminophenyl)porphyrin TAPPH₂, their H and ¹³C

R = OMe

HN

R = OMe

CO

HN

CO

HN

NMR studies and epoxidation of styrene with the corre-

sponding Fe-catalysts to shed light on the inﬂuence of the

handle attachment to the 5,10- and 15,20-positions of the

meso-2-aminophenyl groups compared to the 5,15- and

10,20-meso-positions in enantioselective catalysis.

CO

R

O

R

2

Feα²β²C₁

RESULTS

Fig. 3. FeαβαβC₁porphyrin and modiﬁed catalyst

Synthesis

Rose et al. obtained a new FeααββC₂catalyst by

homologation of the binaphthyl handle BN₁into a new

1,1′-binaphthyl, 2,2′-dimethoxy, 3,3′-dicarbonylchloride

BN₂which gave the epoxide with the opposite conﬁgura-

tion, the (R) styrene epoxide with ee > 97% and turnover

up to 1500 [12]. In this case, the methoxy group remains

untouched as it is too far from the [Fe=O] active site.

Du, Woo and Rose used the iron catalyst FeααββC₁to

perform cyclopropanation of oleﬁns with diazoacetate

[13]. Since Zhang, Gallo et al. [14] independently had

shown that Co porphyrin complexes could also under-

take cyclopropanation [15], Gallo, Rose et al. extended

this study to perform enantioselective cyclopropanation

of oleﬁns catalyzed by Co-porphyrins using CoααββC₂

and another catalyst CoααββC₃obtained after condensa-

tion of the bis-homologated binaphthyl handle (Fig. 4)

[16]. The porphyrin with the shortest handle CoααββC₁

was devoid of catalytic activity. The enantioselectivi-

ties observed, up to 90% ee with cis/trans ratio reaching

11:89, were not as high as those obtained for epoxidation

Tetrakis-(2-aminophenyl)porphyrins o-TAPPH₂were

prepared by reduction of the corresponding tetrakis-(2-

nitrophenyl)porphyrins o-TNPPH₂, which were obtained

by condensation of pyrrole with 2-nitrobenzaldehyde [1].

The statistical mixture of the four atropoisomers αβαβ,

ααββ, αααβ and αααα-o-TAPPH₂was separated by

silica gel chromatography column in the ratio 12.5, 25, 50

and 12.5%. The abundance of the four atropoisomers can

be changed by thermal treatment of the corresponding

nitrophenyl atropoisomers or their Zn derivatives to yield

as the major atropoisomer the αβαβ [20] or the ααββ

one, respectively [21]. We also prepared the binaphthyl

diacid chlorides BN_n[12, 22], n represents the number of

carbons between the binaphthyl residue starting from the

(R)-(+)-1,1′-Bi-2-naphthol. Thus, condensation of the

αβαβ aminoporphyrin with the acid chlorides using high

dilution technique with a syringe pump [11, 12] afforded

the free-base symmetrical porphyrins αβαβC_n(n = 1–3),

respectively in 87, 38 and 26% yield (Chart 1). The goal

J. Porphyrins Phthalocyanines 2010; 14: 647–659

648

e. rOSe et al.

Chart 1. Preparation of αβαβC_nporphyrins

was to compare the inﬂuence of the handle attachment

to the meso-2-aminophenyl groups (at 5,10 and 15,20-

positions compared to 5,15 and 10,20-meso-positions) in

enantioselective catalysis.

Fig. 5. The spectra exhibit limited sets of resonances

(comprising 15 to 17 unequivalent resonances for 70 to

86 protons), indicating high symmetry for these porphy-

rins αβαβC_n. We will discuss successively the chemical

shift values of the NH pyrrolic and amidophenyl protons,

of the meso-phenyl groups, of the β-pyrrolic and the

binaphthyl handle protons, and ﬁnally of the protons of

the methoxy groups which are the best observers of the

porphyrin plane.

NMR assignments

In the absence of X-ray structures of our porphyrins,

we undertook their studies by NMR spectroscopy. The

¹H NMR spectra of the three porphyrins are shown in

Fig. 5. ¹H NMR spectra of αβαβC_nporphyrins (500 MHz, CDCl₃, 20 °C). Top, αβαβC₁; middle, αβαβC₂; bottom, αβαβC₃. Sol-

vent signal or impurities are indicated by an asterisk. The scale of the NH pyrrolic region has been multiplied by four

J. Porphyrins Phthalocyanines 2010; 14: 648–659

ChIral “baSket hanDle” bInaPhthyl POrPhyrInS

649

O

Pyrrolic NH protons. The chemical shifts of these

protons are sensitive to the deformation of the porphyrin

plane. The more planar the macrocycle, the more upﬁeld-

shifted are their chemical shifts [23]. The signals of the

pyrrolic NH of the three porphyrins αβαβC₁, αβαβC₂

and αβαβC₃resonate at -2.06, -3.31 and -2.70 ppm in

CDCl₃. This indicates that in αβαβC₁with the short-

est handle, the porphyrin plane has to be distorted to

accommodate the two binaphthyl residues, the porphyrin

ring causing a smaller shielding anisotropy on the NH

protons. For the other two porphyrins, the NH protons

resonate at expected chemical shift values for planar or

slightly deformed macrocycles.

O

Ar

R

Ar

CH₃

H₃C

O

R

N

H

HN

NH

O

HN

NH

HN

NH

O

NH

N

H

N

HN

N

HN

H

NH

N

HN

O

NH

O

R

O

H₃C

CH₃

HN

R

NH

Ar'

O

H

O

N

4

Gyroscope porphyrins

Ar'

R=Me, CH₂Ph

a) Ar=Ar'=p-C₆H₄

O

3

b) Ar=p-C₆H₄Ar'=m-C₅H₃N

c) Ar=Ar'=m-C₅H₃N

Basket handle porphyrins

Amidophenyl amide protons. The amidophenyl amide

protons of αβαβC₁, αβαβC₂and αβαβC₃resonate at

7.49, 6.18 and 6.35 ppm, respectively, in CDCl₃. The

most deshielded protons belong to the non-homologated

porphyrin αβαβC₁which is again in good agreement

with a non-planar macrocycle and a smaller anisotropy

effect of the porphyrin ring.

N

cyclen

CO

HN

N

CO

N

CO

HN

CO

HN

OC

O

HN

CO

HN

CO

HN

CO

HN

CO

HN

OC

N

Meso-phenyl protons. The nearest hydrogen of the

meso-phenyl group, namely the H₆proton, occupies a key

spectator position of the binaphthyl handle. Therefore, it

is important to assign unambiguously its chemical shift.

Indeed the four aromatic protons H₃-H₆resonate as two

apparent doublets H₃and H₆(J ~ 8 Hz) and two apparent

triplets H₄and H₅(J ~ 8 Hz). The meso-phenyl protons

of other tetrakis-(2-amidophenyl)porphyrins have been

tentatively assigned previously [24]. However Perlmutter

et al. [25] and our group [26] proved deﬁnitively by two

different NMR techniques that this is the H₆proton and

not the H₃proton which is the more shielded meso-aryl

proton. Perlmutter et al. used an elegant application of ¹H

NMR Nuclear-Overhauser technique and we did selective

¹H-¹³C decoupling of the H₃proton, which transformed

the ¹³C off-resonance doublet of the corresponding car-

bon C₃to a singlet. The phenyl protons of αβαβC₁,

αβαβC₂and αβαβC₃porphyrins in this work were

unambiguously assigned from the analysis of 2D ¹H-¹³C

HMBC experiments (Table 1). In particular, carbon C₃

HN

CO

N

OC

N

5

6

Barrel porphyrin

Fig. 6. Amidophenylporphyrins

could be assigned through a correlation with NH proton.

The assignment of other aromatic resonances was based

on the observation of typical ³J_H,Ccorrelations in phenyl

groups. For these porphyrins, the H₄protons resonate

at approximately the same frequency at 7.84, 7.88 and

7.83 ppm.

This is a ﬁngerprint of these 2-amidophenyl porphy-

rins because similar chemical shift values have been

observed in all the porphyrins that we prepared previ-

ously: the “gyroscope” porphyrin 3 [27], the “basket han-

dle” porphyrins 4 [28], the “barrel” porphyrin 6 obtained

by Michael addition of cyclen to the octa-acceptor 5 [29]

and the ααββC_1-3binaphthyl porphyrins [12] (Fig. 6).

Proton H₆experiences a very different chemical shift

in αβαβC₁in comparison with its C₂and C₃counterparts,

being the most unshielded proton. Indeed, the H₆signal

is observed at 8.57, 8.00 and 7.95 ppm, the shielding of

this proton increasing with the length of the handle. Thus

the deshielded H₆protons in αβαβC₁porphyrin are less

inﬂuenced by the anisotropy cone of the macrocycle, in

good agreement again with a deformation of the porphy-

rin plane. Interestingly, the H₃and H₆protons exhibit

larger linewidths in αβαβC₂porphyrin, as compared to

the other two, proton H₆being hardly observable. This

observation will be discussed in relation with methoxy

protons broadening, vide infra.

1

Table 1. H chemical shifts of the meso-phenyl groups of

αβαβC_nand ααββC_nporphyrins

Entry

Compound^a

ArH₃

ArH₄

ArH₅

ArH₆

1

2

3

αβαβC₁

αβαβC₂

αβαβC₃

8.45

8.57

8.72

7.84

7.88

7.83

7.68

7.65

7.44

8.57

8.00

7.95

4

5

6

ααββC₁

ααββC₂

ααββC₃

8.40

8.33

7.92

7.90

7.82

7.69

9.11

8.86

8.85

8.54

7.89

7.82

7.57

7.47

8.15

7.62

β-pyrrolic protons. The β-pyrrolic protons resonate as

two sets of two singlets integrating for four protons each,

as is expected in the case of fast-exchange NH tautomer-

ism and for symmetry reasons [24a] yielding two groups

(2,3,12,13 and 7,8,17,18) of magnetically equivalent pro-

tons. Thus, peaks at 8.80 and 8.66 ppm are found for the

8.70

8.20

7.92

7.78

7.52

7.78

7.90

7.52

^aCDCl₃, 20 °C, 500 MHz.

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Table 2. ¹H chemical shifts of the naphthyl groups of αβαβC_nporphyrins

Compounds^a

H_4′(s)

H_5′(d)

H_6′(t)

H_7′(t)

H_8′(d)

OMe

NH amide

NH pyrrole

αβαβC₁

BINAP₁

∆δ^b

8.36

9.01

0.65

7.37

8.02

0.65

7.48

7.85

0.37

7.63

7.16

-0.47

7.50

7.24

-0.26

7.61

7.12

-0.49

7.12

7.42

0.30

7.28

7.02

-0.26

7.22

7.17

-0.05

6.85

7.53

0.68

7.03

7.43

0.40

6.97

7.36

0.39

6.00

8.11

2.11

6.46

7.89

1.43

6.58

7.80

1.22

0.15

3.46

3.31

~0^c

7.49

9.98

2.49

6.18

8.07

1.89

6.35

8.42

2.07

-2.06

—

αβαβC₂

BINAP₂

∆δ^b

-3.31

—

3.27

~-3.3

1.34

3.19

1.85

—

αβαβC₃

BINAP₃

∆δ^b

-2.70

—

^aCDCl₃, 20 °C, 500 MHz. ^b∆δ = δ(BINAP_n) - δ(ααββC_nporphyrin). ^cVery broad.

αβαβC₁porphyrin whereas peaks at 8.61 and 8.45 are

observed for the αβαβC₂porphyrin and peaks at 8.71

and 8.55 for the αβαβC₃porphyrin.

and 1.34 ppm as a sharp signal in CDCl₃. The methoxy

groups are shielded by 3.31 and 1.85 ppm with respect to

the amido models BINAP_1-3(Fig. 2, Table 3). Unexpect-

edly, for the basket handle αβαβC₂porphyrin, we did

not observe a sharp signal for the 12 protons of the four

methoxy groups. By analyzing more deeply the ¹H NMR

spectrum, an unexpected very broad, ﬂat peak was found

between 0.5 and -1.5 pm.

Naphthalenic protons. The synthesis of binaphthyl

handles substituted by CONHPh, CH₂CONHPh and

(CH₂)₂CONHPh BINAP_1-3(Fig. 2) has been undertaken

to obtain model compounds, vide supra, and to know

which proton is the most shielded by the anisotropy of

the porphyrin during the condensation of the handle to the

tetraaminoporphyrin. The chemical shifts are reported in

Table 2. The ten protons of the naphthyl residue resonate

as ﬁve peaks with one singulet for the protons H_4′, two

doublets for the protons H_5′and H_8′and two triplets for

the protons H_6′and H_7′[30].

¹H, ¹³C NMR data at different temperatures

A possible explanation of the broadening at room

temperature of the methoxy proton signal in αβαβC₂

porphyrin is a conformational equilibrium in interme-

1

diate exchange on the H NMR time scale. In order to

Methoxy protons. The methoxy groups of the αβαβC₁

and αβαβC₃porphyrins resonate respectively at 0.15

probe the dynamics and the nature of this conformational

transition, we decided to perform variable temperature

¹H NMR studies on αβαβC₂, as well as on αβαβC₁

and αβαβC₃porphyrins. A gradually increasing of the

temperature to 40 °C induces an increase of the peak

height of the methoxy group in CDCl₃, as well as that

of H₃and H₆protons (Fig. 7), in good agreement with a

Table 3. ¹H chemical shifts of the OMe groups of αβαβC_nand

ααββC_nporphyrins

Entry

Compound^a

δ(OMe) distal^a

δ(OMe) proximal^a

1

2

αβαβC₁

BINAP₁

∆δ^b

2.97

3.46

-0.63

—

1

faster exchange on the H NMR time scale. Conversely,

a gradual lowering of the temperature to -30 °C in CDCl₃

induces a severe broadening of most resonances. In con-

trast, the spectra recorded at the lowest temperatures

(-40 °C and -50 °C) are characterized by sharp lines

and show a high complexity due to numerous splittings

of aromatic and aliphatic resonances, indicating a slow

exchange regime on the ¹H NMR time scale for all reso-

nances. These spectral changes are fully reversible upon

warming up to room temperature. In order to character-

ize the different magnetic environments observed at low

temperature, 2D NMR spectra were recorded at -50 °C.

3

0.49

4.09

-0.51

—

4

αβαβC₂

BINAP₂

∆δ^b

1.98

5

3.27

6

1.29

3.78

1.86

—

7

αβαβC₃

BINAP₃

∆δ^b

2.34

8

3.19

9

0.85

1.33

—

10

11

12

13

14

15

αβαβC₁

∆δ

0.15

3.31

~0^c

—

1

The 2D H-¹³C HSQC spectrum (Fig. 8) reveals that

αβαβC₂

∆δ

—

up to four environments can be observed for each aro-

matic and aliphatic CH resonance. Four distinct correla-

tion pathways could be assigned for the aromatic spin

~-3.3 ppm

1.34

—

αβαβC₃

∆δ

—

1.85

—

1

systems in the 2D H-¹H COSY experiments. The four

^aCDCl₃, 20 °C, 500 MHz. ^b∆δ = δ(BINAP_n) - δ(ααββC_npor-

sets of chemical shifts can be divided into two differ-

ent subgroups of almost equivalent signals (or closed to

phyrin). ^cVery broad.

J. Porphyrins Phthalocyanines 2010; 14: 650–659

ChIral “baSket hanDle” bInaPhthyl POrPhyrInS

651

Fig. 7. Variable temperature 1D ¹H NMR spectra of αβαβC₂porphyrin (CDCl₃, 500 MHz).

each other). The unambiguous assignments of aromatic

the binaphthyl handles. Concerted motion of meso-phe-

nyl and binaphthyl handles would position alternatively

the methoxy group in a proximal or in a distal position

with respect to the porphyrin plane, leading to chemical

shifts around -3 and +2 ppm, respectively (Fig. 8).

The variable temperature NMR studies performed

on αβαβC₁porphyrin did not show any exchange phe-

nomenon beside the NH tautomerism of the porphyrin

ring [31]. Indeed, the NH- and β-pyrrolic protons exhibit

gradual broadening as the temperature is lowered, and

signal coalescence occurs around -35 °C (Fig. S1, see

Supporting information). Two asymmetric signals are

observed for the NH pyrrolic protons at -50 °C, with a

~2:1 intensity ratio. The β-pyrrolic protons that appear as

two singlets at room temperature give rise to four signals

with two sharp peaks (visible on the HSQC spectrum,

1

groups were facilitated by comparison with the H, ¹³C

assignments obtained at room temperature. In particular,

for each resonance, the average of the chemical shifts of

the four states should be close to the fast-exchange aver-

aged chemical shift value observed at room temperature.

The chemical shift comparison of each resonance in the

four states shows that methoxy groups exhibit the larg-

est variation (5.7 ppm) and that the CH resonances at

positions 3 and 6 in the phenyl group are also strongly

affected. The change in magnetic environment in the phe-

nyl groups could be induced by rotation with respect to

the porphyrin ring leading to different orientations. The

large change observed in the methoxy groups is probably

due to a different positioning with respect to the porphy-

rin plane associated with two distinct conformations of

J. Porphyrins Phthalocyanines 2010; 14: 651–659

652

e. rOSe et al.

Fig. 8. Superimposition of 2D ¹H-¹³C HSQC spectra of αβαβC₂porphyrin (CDCl₃, 500 MHz) recorded at 40 °C (red) and -50 °C

(black). The assignments of the four spin systems of amidophenyl groups are indicated with letters a–d.

Fig. S2) and two broad signals. The signals of pyr-

rolic protons can be readily interpreted by considering

a tautomeric equilibrium in slow exchange on the NMR

time scale and because of the chiral environment of the

binaphthyl handles. Interestingly, the asymmetric signals

observed for the pyrrolic protons indicate that the two

tautomeric forms have different stabilities. The methoxy

and binaphthyl protons do not show signiﬁcant changes

upon temperature lowering. Protons H₃and H₆of the

amidophenyl groups exhibit a slight chemical shift varia-

tion and the proton H₃signal becomes signiﬁcantly more

broadened than other signals. These chemical shift varia-

tions can be accounted for by their spatial proximity to

the porphyrin ring (Fig. S2).

J. Porphyrins Phthalocyanines 2010; 14: 652–659

ChIral “baSket hanDle” bInaPhthyl POrPhyrInS

653

In the case of αβαβC₃porphyrin, the NH- and

β-pyrrolic protons show similar behavior as in αβαβC₁

porphyrin upon temperature decreasing (Fig. S3). How-

ever, H₃and H₆amidophenyl protons and methoxy pro-

tons clearly undergo an exchange phenomenon since

they show gradual broadening, coalescence and splitting

in two signals as the temperature is decreased. For each

proton, the two states have close chemical shifts and have

different populations, with a ~2:1 intensity ratio. Note-

worthy, the protons of both methylene groups also show a

variation of their chemical shifts with temperature, and an

increase in chemical shift difference is observed between

diastereotopic protons at low temperature. Interestingly,

the chemical shifts of the methoxy protons in the two

states at low temperature strongly differ from the chemi-

cal shift at 20 °C, with +0.9 ppm deshielding (Fig. S4).

resonate at two different frequencies in α²β²C_nporphy-

rins play the role of privileged spectators of the environ-

ment of the porphyrin. The proximal MeO group which is

located near the center of the porphyrin resonates at low

frequencies and the distal one which points outward from

the tetrapyrrolic core is not affected as much by the aniso-

tropic current of the porphyrin ring and resonates at higher

frequency (Table 3, entries 1,4,7). The chemical shifts of

the proximal methoxy groups in α²β²C₁and α²β²C₂are

negative, which correspond to huge shieldings of 4.09 and

3.78 ppm, respectively (entries 3 and 6). The shielding ∆δ

is the difference of chemical shift of the methoxy group

of 2-methoxy, 3-amido-binaphthyl derivatives BINAP_n

(n = 1–3) (Table 3, entries 2,5,8) that we prepared inde-

pendently and the chemical shift of the methoxy group

of the free porphyrins α²β²C_n(Table 3, entries 1,4,7).

These high shieldings had also been encountered for the

terephthalic protons C₆H₄in the handle of the gyroscope

porphyrin 3 and basket handle porphyrin 4 (Fig. 6). For

example, the shieldings were 4.43 and 4.03 ppm in the

same solvent CDCl₃for 3b and 4 R=Me [33].

For porphyrins αβαβC_n, the methoxy groups are also

spectators of the porphyrin environment. Therefore the

observation of exchange-broadened methoxy groups in

the case of the C₂derivative was particularly intriguing

andwasfurtherinvestigatedtogetinformationontheposi-

tion of the binaphthyl handles with respect to the porphy-

rin plane. The comparison of the ¹H, ¹³C NMR chemical

shifts for the three αβαβC_nporphyrins and their change

with temperatures yield interesting information on the

different populations adopted by these systems and the

dynamics of their conformational equilibria. The short,

constrained amide handle in αβαβC₁porphyrin leads to

signiﬁcant deviation from planarity of the porphyrin ring,

in comparison with αβαβC₂and αβαβC₃porphyrins.

The small temperature dependency of the chemical shift

of protons in αβαβC₁suggests that the overall structure

is quite rigid. The signals of the binaphthyl handle are

barely affected by the tautomerism in the porphyrin ring

and remain symmetric in the studied temperature range

(-50 °C to +40 °C). The deformation of the porphyrin

ring should, a priori, push away the αβαβC₁binaph-

thyl handle but the reverse cannot be excluded with an

approach of the handles towards the deformed porphyrin.

Indeed, this kind of deformation had been observed in the

case of a Ni-terephthalic, pyridinic bis-handle porphyrin

ArPyNi for which an X-ray structure showed precisely

the deformation of both handles towards the deformed

porphyrin plane (Fig. 9). Indeed, the distance between

the porphyrin and the distal strap is 3.4 Å, the shortest

distance ever reported for this type of structure. The pyri-

dyl ring of the proximal strap is almost parallel to the 4N

plane, the dihedral angle between the two planes is 13.6°.

The phenyl cap is parallel to the 4N plane and stands

precisely in the apical position of the Ni atom at 3.40 Å

[34]. The macrocycle exhibits a rufﬂed conformation

[35]: the average Cm deviation is 0.52 Å with respect to

Catalytic activity toward epoxidation reactions

Epoxidation reactions catalyzed with FeαβαβC_nwere

examined with iodosylbenzene as the oxidant and excess

oleﬁn substrates (catalyst:PhIO:substrate = 1:100:1000)

by using the same experimental conditions as the ones

previously described for FeααββC_nn = 1,2 [3b, 11, 12].

The epoxidation of styrene with the FeαβαβC₁catalyst

gave the (S)-epoxide as the major product with 38% ee

at 25 °C and 54% at -5 °C whereas the ee reached 83%

with the FeααββC₁catalyst [11, 32]. Furthermore, the

activity is lower. Instead of rates of around 40 turnover/

min, we observed rates 400 times lower for the epoxida-

tion of styrene. Thus, the active site is hindered by the

binaphthyl handle and the oleﬁn approach is difﬁcult,

consequently both selectivity and activity diminished.

This clearly shows the advantage of an open access to

the active site when the same binaphthyl handles BN_nare

attached to the ααββ geometry. With the homologated

catalyst FeαβαβC₂, epoxidation of styrene gives the (R)

epoxide as the major epoxide in 99% yield and 32% ee

with a turnover frequency of 15 h^-1. Indeed, the active

site is more open and the rate is increased by a factor of

2.5. With the FeαβαβC₃catalyst, epoxidation of styrene

gives the (R) epoxide as the major epoxide in 99% yield

and 43% ee with a turnover frequency of 10 h^-1and 52%

ee at -5 °C. Thus for the FeαβαβC_nporphyrins studied

in this work, the results of the epoxidation catalysis show

the same particularity as for the FeααββC_nporphyrins:

the (S) epoxide is the major product when the FeαβαβC₁

porphyrin is used as catalyst whereas the (R) epoxide

is the major one when the FeαβαβC₂and FeαβαβC₃

catalysts are used.

DISCUSSION

We have shown previously that relevant information

on the conformation of binaphthyl handle-free porphy-

1

rins α²β²C_ncan be obtained from H NMR chemical

shift analysis. In particular, the methoxy groups which

J. Porphyrins Phthalocyanines 2010; 14: 653–659

654

e. rOSe et al.

terephthalic handle Ar

Ph

H

O

ArPyNi

major (S) epoxide

major (R) epoxide

NH

O

H

Ph

O

NH

O

favored re face

favored si face

O

5

NH

Ph

10

Ni

20

15

N

Ph

O

MeO

O

NH

O

NH

*

N

*

N

NH

O

OMe

NH

O

N

binaphthyl residue

N

pyridinic handle Py

FeαβαβC₂

FeαβαβC₃

FeαβαβC₁

Fig. 9. Schematic representation of the X-ray structure of

ArPyNi

*

represents [Fe=O]

Fig. 10. Possible approach of the oleﬁns toward the Fe=O active

site in FeαβαβC₁porphyrin

the 24-atom least-squares plane and the average dihedral

angle of two opposite pyrrole planes is 32.9°.

changes of amidophenyl and naphthyl groups that are

probably concerted with methoxy motions. The inter-

conversion between the two low-energy conformations

of the binaphthyl handles occurs at room temperature on

fast exchange on the ¹H NMR time scale, giving rise to a

time-averaged, symmetric spectrum, with the exception

of methoxy groups that are in intermediate exchange.

The comparison of catalytic activities clearly shows

the importance of the attachment of the binaphthyl han-

dles BINAP_itoward the meso-phenyl groups. Indeed,

with the catalysts ααββC₁and ααββC₂, the ee are excel-

lent and the binaphthyl handles discriminate between the

re and the si approach of styrene whereas with the αβαβ

catalysts, the ee cannot be compared and the handle, too

close to the active site, prevents the epoxidation from

occurring at a good rate. Thus, this study shows that the

active site must be open enough and that the binaphthyl

handles attached to the 5,10- and 15,20-meso-carbons is

the best compromise to afford good yields, enantiomeric

excesses and rates. The lengths of the binaphthyl han-

dles in the αβαβC_ncompounds inﬂuence the selectiv-

ity of the reaction. We could suggest that the FeαβαβC₁

complex, as in the FeααββC₁case, is transformed into

a quinone type intermediate. The styrene approach with

its large phenyl group occupying the space next to the

outward leaning lobe, represents the favored low energy

path. This leads to the major (S)-epoxide via a re face

approach of the oleﬁn towards the [Fe=O] active site.

With the FeαβαβC₂and FeαβαβC₃catalysts, the (R)

styrene epoxide is recovered as the major one which cor-

responds to the si face approach of the oleﬁn towards the

active site in order to avoid the methoxy group (Fig. 10).

The presence of the two methylene linkers in αβαβC₃

porphyrin removes the steric strain since the porphyrin ring

is more planar. This porphyrin is also more ﬂexible, as sug-

gested by the strong temperature dependency of the chem-

ical shifts of methoxy and methylenic protons. Indeed, the

chemical shift variations can be interpreted by consider-

ing a conformational equilibrium with increased popula-

tion differences at low temperatures. In the conformer(s)

stabilized at low temperature, the methoxy groups are less

shielded and would point away from the porphyrin ring.

The protons are also sensitive to the tautomerism in the

porphyrin ring since two slightly different sets of chemi-

cal shifts are observed for protons in the vicinity of the

porphyrin under slow exchange conditions.

The αβαβC₂porphyrin shows unexpected features,

with the presence of up to four states under slow exchange

conditions and large chemical shift variations. These four

environments can be grouped in two subsets of two states

showing close chemical shifts, which splitting could be

due to the tautomerism of the porphyrin ring, as observed

in αβαβC₃porphyrin. In each subset, unequal intensi-

ties are observed for the two forms, underlining differ-

ent stabilities of the two porphyrin systems. The larger

chemical shift difference between the two subsets, in

particular for methoxy signals, can be explained by a

dynamic equilibrium affecting the binaphthyl handles.

Thus, the handles interconvert between two conforma-

tions with respect to the porphyrin ring. The consider-

able change in magnetic environments experienced by

methoxy groups clearly indicates that they alternatively

adopt a highly shielded proximal position (–3 ppm) and

a less shielded distal position with respect to the por-

phyrin ring (2 ppm). Similar chemical shift values have

been observed in ααββC₂porphyrins having the same

binaphthyl handles but with different attachments to the

meso 5,10 and 15,20 2-aminophenyl groups, in which

methoxy groups have two different environments, inside

and outside the porphyrin core. The ¹³C chemical shift

variations at 3 and 4′-positions also suggest orientation

EXPERIMENTAL

General information

All reagents were used as supplied commercially

unless otherwise noted. THF and diethyl ether were

J. Porphyrins Phthalocyanines 2010; 14: 654–659

ChIral “baSket hanDle” bInaPhthyl POrPhyrInS

655

distilled from sodium under N₂before use. BINAP_n[12,

16], αβαβ and ααββ-o-TAPP were prepared according

the solvents evaporated to give a yellow solid that was

puriﬁed by chromatography column on silica gel (SiO₂

15–40 µm, cyclohexane/dichloromethane: 1/9) to afford

the desired product as a yellow golden solid (129 mg,

79%). ¹H NMR (400 MHz, CDCl₃, 298 K): δ_H, ppm 3.27

1

to literature method [1]. H and ¹³C NMR spectra were

recorded on a Bruker ARX200, a Bruker Avance 400, a

Bruker DRX 500 or a Bruker Avance III 500 MHz spec-

trometer equipped with a TCI cryoprobe. All chemi-

cal shifts are in ppm and referenced to solvent signals:

7.26 ppm and 77.16 ppm for ¹H and ¹³C spectra in CDCl₃,

7.16 ppm and 128.06 ppm for ¹H and ¹³C spectra in C₆D₆.

All the coupling constants are in Hertz (Hz). Infrared

spectra were recorded on a Nicolet-Avatar 320 FT-IR.

UV-vis spectra were recorded on UVIKON 923 Spec-

trometer. Wavelengths (l) are in nanometers (nm). MS/

HRMS were obtained at the UPMC. Enantiomeric excess

were determined on aVarian CP-3380 gas chromatograph

equipped with ﬂame ionization detector and a Cyclodex

B 236M capillary column (50 m × 0, 25 µM, DF=0,

25 µM) and using helium as a vector gas.

2

(s, 6H, OMe), 3.90 (2H, d, J = 14.4 Hz, CH_{2 benz}), 4.03

2

3

(2H, d, J = 14.4 Hz, CH_{2 benz}), 7.02 (2H, td, J = 8.1

Hz, ⁴J = 0.9 Hz, H_Ar), 7.20–7.28 (2H + 6H, m, H_5′+H_Ar),

7.41–7.46 (6H, m, H_7′+H_Ar), 7.89 (2H, dd, J = 8.1 Hz,

3

⁴J = 1.2 Hz, H_8′), 8.02 (2H, s, H_4′), 8.07 (2H, s, NH).

¹³CNMR(100MHz,CDCl₃,298K):δ_C,ppm41.3(CH_2benz),

61.0 (OMe), 119.7 (C_Ar), 124.2 (C_6′), 125.6 (C_5′), 125.7

(C_7′), 124.7 (C_q), 128.1 (C_8′), 128.5 (C_q), 129.0 (C_Ar),

130.9 (C_q), 131.3 (C_4′), 133.9 (C_q), 138.2 (C_q), 154.5

(C_q), 169.3 (CO). HR MS: m/z 603.2238 (calcd. for

[C₃₈H₃₂N₂O₄+ Na]⁺603.2260). [α]_D²⁰: +6.4 (c = 0.5 in

THF). Anal. calcd. for C₃₈H₃₂N₂O₄: C, 78.60; H, 5.04.

Found: C, 78.49; H, 5.11.

Synthesis

of

(R)-(-)-3,3′-(2,2′-dimethoxy-1,1′-

binaphthyl-3,3′-diyl)bis(N-phenylpropanamide)

BINAP₃. To a solution of Et₃N (70 µL, 0.5 mmol) and

freshly distilled aniline (50 µL, 0.497 mmol) in 3 mL of

dichloromethane was added dropwise a solution of dia-

cid chloride BN₃[16] (102 mg, 0.222 mmol) in 4 mL

of dry dichloromethane. The mixture was stirred over-

night at room temperature. The yellow solution was then

extracted with water, saturated NaHCO₃solution and HCl

3N. The organic layer was dried over MgSO₄and the sol-

vents evaporated to give an orange oil that was puriﬁed

by chromatography column on silica gel (SiO₂15–40 µm,

cyclohexane/dichloromethane: 1/9) to afford the desired

product as an orange thick solid (84 mg, 62%). ¹H NMR

(400 MHz, CDCl₃, 298 K): δ_H, ppm 2.87–2.94 (4H, m,

CH_{2 benz′}), 3.19 (6H, s, OMe), 3.27–3.36 (4H, m, C_{H2 benz}),

7.07 (2H, t, ³J = 7.6 Hz, H_Ar), 7.12 (2H, d, ³J = 8.1 Hz, ⁴J =

Synthesis

Synthesisof(R)-(-)-2,2′-dimethoxy-N³,N^3′-diphenyl-

1,1′-binaphthyl-3,3′-dicarboxamideBINAP₁.Toasolu-

tion of Et₃N (0.158 mL, 1.124 mmol) and freshly distilled

aniline (0.1 mL, 1.18 mmol) in 3 mL of dichloromethane

was added dropwise a solution of diacid chloride BN₁

(225 mg, 0.559 mmol) in 4 mL of dry dichloromethane.

The mixture was stirred overnight at room temperature.

The yellow solution was then extracted with water, satu-

rated NaHCO₃solution and HCl 3N. The organic layer

was dried over MgSO₄and the solvents evaporated to

give a yellow solid that was puriﬁed by chromatogra-

phy column on silica gel (SiO₂15–40 µm, cyclohexane/

dichloromethane: 1/9) to afford the desired product as a

1

yellow thick solid (102 mg, 33%). H NMR (400 MHz,

3

4

CDCl₃, 298 K): δ_H, ppm 3.46 (6H, s, OMe), 7.16 (2H, m,

H_5′), 7.37–7.42 (2H + 6H, m, H_6′, H_Ar), 7.53 (2H, td, ³J =

8.2 Hz, ⁴J = 1.2 Hz, H_7′), 7.76 (4H, dd, ³J = 8.2 Hz, ⁴J =

1.2 Hz, H_Ar), 8.11 (2H, d, ³J = 7.9 Hz, H_8′), 9.01 (2H, s,

H_4′), 9.98 (2H, s, NH). ¹³C NMR (100 MHz, CDCl₃, 298

K): δ_C, ppm 62.2 (OMe), 120.3 (C_Ar), 124.6 (C_Ar), 125.5

(C_5′), 125.8 (C_q), 126.3 (C_7′), 127.3 (C_q), 129.0 (C_6′),

129.2 (C_Ar), 129.9 (C_8′), 130.5 (C_q), 134.7 (C_4′), 135.5

(C_q), 138.3 (C_q), 153.2 (C_q), 163.2 (CO). HR MS: m/z

575.1926 (calcd. for [C₃₆H₂₈N₂O₄+ Na]⁺575.1947).

[α]_D²⁰: -74.0 (c = 0.5 inTHF).Anal. calcd. for C₃₆H₂₈N₂O₄:

C, 78.24; H, 5.11%. Found: C, 78.31; H, 5.04.

Synthesis of (R)-(+)-2,2′-(2,2′-dimethoxy-1,1′-

binaphthyl-3,3′-diyl)bis(N-phenylacetamide)

BINAP₂. To a solution of Et₃N (80 µL, 0.6 mmol) and

freshly distilled aniline (53 µL, 0.562 mmol) in 3 mL of

dichloromethane was added dropwise a solution of dia-

cid chloride BN₂[12] (121 mg, 0.281 mmol) in 4 mL

of dry dichloromethane. The mixture was stirred over-

night at room temperature. The yellow solution was then

extracted with water, saturated NaHCO₃solution and

HCl 3N. The organic layer was dried over MgSO₄and

0.9 Hz, H_5′), 7.17 (2H, td, J = 8.1 Hz, J = 1.2 Hz, H_6′,

3

H_Ar), 7.24–7.29 (4H, m, H_Ar), 7.36 (2H, td, J = 8.1 Hz,

⁴J = 1.2 Hz, H_7′), 7.55 (d, ³J = 7.7 Hz, 4H, H_Ar), 7.85 (2H,

s, H_4′). 8.42 (2H, s, NH). HR MS: m/z 631.2551 (calcd.

for [M + Na]⁺631.2573). [α]_D²⁰: -9.8 (c = 0.5 in THF).

Anal. calcd. for C₄₀H₃₆N₂O₄: C, 78.92; H, 5.96%. Found:

C, 78.76; H, 5.81.

Synthesis of αβαβC₁basket handle porphyrin. A

500mLtwo-neckround-bottomﬂaskequippedwitharub-

ber and an argon inlet is charged with 150 mL of freshly

distilled tetrahydrofuran on sodium. Freshly dried N,N-

diethylanilin (0.18 mL, 2.08 mmol) was added. In another

ﬂask under argon, αβαβ-tetra-aminophenylporphyrin

TAPPH₂[1] (180 mg, 0.26 mmol) was dissolved in 20 mL

of tetrahydrofuran and the resulting solution is trans-

ferred into two well-dried 10 mL syringes. The freshly

synthesized diacid chloride BN₁[12] (0.55 mmol) was

dissolved in 10 mL of dichloromethane and loaded into

a dried 10 mL syringe. A syringe pump was equipped

with the three syringes, and the reactants were simultane-

ously added in the two-neck ﬂask over 2 h at 0 °C. Then

the red solution was allowed to stir at room temperature

J. Porphyrins Phthalocyanines 2010; 14: 655–659

656

e. rOSe et al.

overnight. The solvent was then removed under vacuum,

and the dark purple residue puriﬁed by chromatography

columnonsilicagel(SiO₂15µm, eluentdichloromethane/

methanol: 99/1) to afford the bis-strapped porphyrin as

MS: m/z 1486.5276 ([M + Na] calcd. for C₉₆H₇₁N₈O₈Na

1486.5248). UV-vis (CH₂Cl₂): l_max, nm (log ε) 420

(5.61), 513 (4.31), 546 (3.77), 588 (3.86), 646 (3.53).

Anal. calcd. for C₉₆H₇₀N₈O₈: C, 78.78; H, 4.82%. Found:

C, 78.62; H, 4.91.

1

a red-purple solid (318 mg, 87%). H NMR (500 MHz,

CDCl₃, 293 K): δ_H, ppm -2.06 (2H, br s, NH_pyr), 0.15

Synthesis of αβαβC₃basket handle porphyrin. A

500mLtwo-neckround-bottomﬂaskequippedwitharub-

ber and an argon inlet is charged with 150 mL of freshly

distilled tetrahydrofuran on sodium. Freshly dried N,N-

diethylanilin (0.28 mL, 3.2 mmol) was added. In another

ﬂask under argon, αβαβ-tetra-aminophenylporphyrin

TAPPH₂(220 mg, 0.32 mmol) was dissolved in 20 mL

of tetrahydrofuran and the resulting solution is transferred

into two well dried 10 mL syringes. The freshly synthe-

sized diacid chloride BN₃[16] (350 mg, 0.7 mmol) was

dissolved in 10 mL of dichloromethane and loaded into a

dried 10 mL syringe. A syringe pump was equipped with

the three syringes, and the reactants were simultaneously

added in the two-neck ﬂask over 2 h at 0 °C. Then the red

solution was allowed to stir at room temperature over-

night. The solvent was then removed under vacuum, and

the dark purple residue puriﬁed by chromatography col-

umn on silica gel (SiO₂15 µm, eluent petroleum ether/

chloroform: 3/7) to afford the bis-strapped porphyrin as

3

4

(12H, s, OMe), 6.00 (4H, dd, J = 8.6 Hz, J = 0.7 Hz,

H_8′), 6.85 (4H, ddd, ³J = 8.5 Hz, ³J = 6.7 Hz, ⁴J = 1.2 Hz,

H_7′), 7.12 (4H, ddd, ³J = 8.3 Hz, ³J = 6.7 Hz, ⁴J = 0.9 Hz,

H_6′), 7.49 (4H, s, NH), 7.63 (4H, d, ³J = 8.2 Hz, H_5′), 7.68

(4H, td, ³J = 7.6 Hz, ⁴J = 1.2 Hz, H₅), 7.84 (4H, td, ³J =

8.0 Hz, ⁴J = 1.5 Hz, H₄), 8.36 (4H, s, H_4′), 8.45 (4H, dd,

4

3

³J = 8.3 Hz, J = 1 Hz, H₃), 8.57 (4H, dd, J = 7.5 Hz,

⁴J = 1.6 Hz, H₆), 8.66 (4H, s, H_β), 8.80 (4H, s, H_β). ¹³C

NMR (125 MHz, CDCl₃, 293K): δ_C, ppm 58.4 (OMe),

113.6 (C_meso), 122.8 (C_1′), 123.7 (C₃), 123.9 (C₅), 124.4

(C_8′), 124.5 (C_3′), 125.6 (C_6′), 128.4 (C_7′), 129.17 (C_5′),

129.19 (C_4′a), 130.0 (C₄), 131.6 (C_β), 131.9 (C₁), 132.4

(C_β), 132.7 (C₆), 134.3 (C_4′), 135.0 (C_8′a), 139.5 (C₂),

151.3 (C_2′), 163.0 (C_CO). HR MS: m/z 1430.4615 (calcd.

for [C₉₂H₆₂N₈O₈+Na] 1430.4622). UV-vis (CH₂Cl₂): l_max

,

nm (log ε) 423 (5.54), 517 (4.40), 550 (3.07), 590 (3.90),

645 (3.40). Anal. calcd. for C₉₂H₆₂N₈O₈: C, 78.51; H,

4.44%. Found: C, 78.32; H, 4.29.

1

Synthesis of αβαβC₂basket handle porphyrin. A

250mLtwo-neckround-bottomﬂaskequippedwitharub-

ber and an argon inlet is charged with 150 mL of freshly

distilled tetrahydrofuran on sodium. Freshly dried N,N-

diethylanilin (0.4 mL, 4.59 mmol) was added. In another

ﬂask under argon, αβαβ-tetra-aminophenylporphyrin

TAPPH₂(303 mg, 0.45 mmol) was dissolved in 20 mL

of tetrahydrofuran and the resulting solution is transferred

into two well dried 10 mL syringes. The freshly synthe-

sized diacid chloride BN₂[12] (439 mg, 1 mmol) was

dissolved in 10 mL of dichloromethane and loaded into a

dried 10 mL syringe. A syringe pump was equipped with

the three syringes, and the reactants were simultaneously

added in the two-neck ﬂask over 3 h at 0 °C. Then the red

solution was allowed to stir at room temperature over-

night. The solvent was then removed under vacuum, and

the dark purple residue puriﬁed by chromatography col-

umn on silica gel (SiO₂15 µm, eluent dichloromethane/

methanol: 99/1) to afford the bis-strapped porphyrin as

a red-purple solid (126 mg, 26%). H NMR (500 MHz,

CDCl₃, 293 K): δ_H, ppm -2.70 (2H, br s, NH_pyr), 1.34

(12H, s, OMe), 1.50–1.68 (8H, m, CH_{2 homobenz}), 2.26–2.44

(8H, m, CH_{2 benz}), 6.35 (4H, s, NH), 6.58 (4H, d, ³J = 8.5

Hz, H_8′), 6.97 (4H, td, ³J = 7.7 Hz, ⁴J = 1.0 Hz, H_7′), 7.22

(4H, td, ³J = 7.3 Hz, ⁴J = 0.8 Hz, H_6′), 7.44 (4H, td, ³J =

7.5 Hz, ⁴J = 1.2 Hz, H₅), 7.48 (4H, s, H_4′), 7.61 (4H, d, ³J =

8.2 Hz, H_5′), 7.83 (4H, td, ³J = 8.0 Hz, ⁴J = 1.3 Hz, H₄),

7.95 (4H, dd, ³J = 7.6 Hz, ⁴J = 1.3 Hz, H₆), 8.55 (4H, s,

3

H_β), 8.71 (4H, s, H_β), 8.72 (4H, d, J = 8.0 Hz, H₃). ¹³C

NMR (125 MHz, CDCl₃, 293 K): δ, ppm 27.2 (C_benz),

38.7 (C_homobenz), 58.9 (OMe), 114.4 (C_meso), 121.0 (C₃),

123.0 (C₅), 124.0 (C_1′), 124.9 (C_6′), 125.3 (C_8′), 125.9

(C_7′), 127.4 (C_5′), 129.3 (C_4′), 130.1 (C₄), 130.4 (C₁, C_4′a),

131.1 (C_β), 132.1 (C_β), 133.1 (C_3′, C_8′a), 134.3 (C₆), 138.8

(C₂), 153.9 (C_2′), 170.6 (C_CO). HR MS: m/z 1542.5858

(calcd. for [M + Na] 1542.5874). UV-vis (CH₂Cl₂): l_max

,

nm (log ε) 419 (5.56), 514 (4.41), 547 (3.88), 587 (3.94),

643 (3.52). Anal. calcd. for C₁₀₀H₇₈N₈O₈: C, 79.03; H,

5.17%. Found: C, 78.96; H, 5.28.

1

a red-purple solid (220 mg, 35%). H NMR (500 MHz,

CDCl₃, 293 K): δ_H, ppm -3.31 (2H, br s, NH_pyr), ~0 (12H,

Standard iron metalation procedure. In a typical

experiment, αβαβC_nfree-base (10 mg, 7 µmol) and FeBr₂

(50 mg, 0.23 mmol) were added to glacial acetic acid

(5 mL) and brought to reﬂux under argon for 48 h for the

αβαβC₁porphyrin, 8 h at 90 °C for the αβαβporphyrin

and for 4 h at 90 °C for the αβαβC3 porphyrin. After

this reaction time, UV-vis monitoring conﬁrmed that the

reaction had reached completion. Excess of acetic acid

was then removed under vacuum, and the residue taken

in CH₂Cl₂. The organic phases were washed with dilute

HCl (1 M), dried over Na₂SO₄, ﬁltered through a pad of

silica gel (SiO₂20–40 µm) and evaporated to dryness to

afford chloro-iron complexes FeαβαβC₁in 94% yield,

3

vbr s, OMe), 2.82 (4H, br d, J = 14 Hz, CH_{2 benz}), 3.04

(4H, d, ³J = 14 Hz, CH_{2 benz}), 6.18 (4H, s, NH), 6.46 (4H,

3

d, J = 8.5 Hz, H_8′), 7.03 (4H, t, J = 7.7 Hz, H_7′), 7.28

3

(4H, H_6′), 7.37 (4H, s, H_4′), 7.50 (4H, d, J = 8.0 Hz,

3

H_5′), 7.65 (4H, t, J = 7.4 Hz, H₅), 7.88 (4H, t, J = 7.9

Hz, H₄), 8.00 (4H, br s, H₆), 8.45 (4H, s, H_β), 8.57 (4H,

br s, H₃), 8.61 (4H, s, H_β). ¹³C NMR (125 MHz, CDCl₃,

313K): δ_C, ppm 38.4 (C_benz), 113.9 (C_meso), 121.9 (C₃),

122.3 (C_1′), 123.1 (C₅), 124.9 (C_6′), 125.1 (C_8′), 126.1

(C_7′), 126.6 (C_3′), 127.7 (C_5′), 129.0 (C_4′), 129.9 (C_4′a),

130.0 (C₄), 131.0 (C₁), 132.4 (C_8′a), 131.1 (C_β), 132.2

(C), 134.6 (C₆), 138.8 (C₂), 152.9 (C_2′), 169.1 (C_CO). HR

J. Porphyrins Phthalocyanines 2010; 14: 656–659

ChIral “baSket hanDle” bInaPhthyl POrPhyrInS

657

FeαβαβC₂in 95% yield and FeαβαβC₃quantitatively as

brown powders. αβαβC₁FeCl. HR MS: m/z 1461.3971

(calcd. for [M - Cl + H]⁺1461.3962). UV-vis (CH₂Cl₂):

epoxidation of styrene, the best ee being only 52% for the

formation of the (R) styrene oxide.

l

_max, nm 419, 509. αβαβC₂FeCl. HR MS: m/z 1517.4537

(calcd. for [M - Cl + H]⁺1517.4588). UV-vis (CH₂Cl₂):

_max, nm 417, 509. αβαβC₃FeCl. HR MS: m/z 1573.5177

(calcd. for [M - Cl + H]⁺1573.5214). UV-vis (CH₂Cl₂):

_max, nm 419, 512.

Acknowledgements

We express our thanks to Prof. B. Andrioletti, Drs. E.

Brulé, S. Fantauzzi, C. Piangiolino, F. Rose-Munch and

students W. Assaf, A. Eloi and M. Poizat for contributing

to this work. E. Rose thanks the CNRS for their ﬁnancial

support and E. Rose and E. Gallo thank Galileo program

for a HC grant. O. Lequin thanks E. Miclet for fruitful

discussion.

l

General procedure for asymmetric oleﬁn epoxidation

In a dry Schlenk tube equipped with a stir bar and

purged under argon, is introduced a 1.0 mL solution of

dried dichloromethane containing 0.50 µmol of catalyst

[17], 500 µmol of oleﬁn and 10.0 µL of internal standard

(80.0 µmol of 1,2,4-trichlorobenzene). While stirring

vigorously, 100 equivalents (50 µmol, 11 mg) of solid

iodosylbenzene is added to the reaction. At appropriate

intervals, less than 0.1 mL of the solution is removed

from the reaction mixture which is loaded on a 60 µm

silica pipette column. Elution with diethyl ether removes

everything from the column except the catalyst and unre-

acted iodosylbenzene. The ﬁltrate is then concentrated

under nitrogen ﬂux, and a 2 µL sample is shot into the

chiral GC column [18] for yield, turnover number and

enantiomeric excess analysis. GC retention times for sty-

rene oxides: 24.59 min for the (R) epoxide and 25.34 min

for the (S) epoxide.

Supporting information

Figures S1–S4 are given in the supplementary material.

This material is available free of charge via the Internet at

http://www.worldscinet.com/jpp/jpp.shtml.

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J. Porphyrins Phthalocyanines 2010; 14: 659–659

Article Doi

Chiral "basket handle" binaphthyl porphyrins: Synthesis, catalytic epoxidation and NMR conformational studies

DOI: 10.1142/S1088424610002483

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Article abstract of DOI:10.1142/S1088424610002483

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