Rhodium-catalyzed asymmetric arylation of α,β-unsaturated imines with arylstannanes. Catalytic asymmetric synthesis of allylic amines

Article abstract of DOI:10.1016/S0040-4020(01)00075-8

Catalytic asymmetric arylation of N-alkylidenesulfonamides 1a-d, which are prepared from α,β-unsaturated aldehydes and 4-nitrobenzenesulfonamide, with aryltrimethylstannanes 2m-p proceeded in the presence of 3 mol% of a rhodium catalyst coordinated with (R)-MOP ligand in dioxane at 110°C to give sulfonamide of allylic amines (R)-3 with high enantioselectivity (up to 96% ee) in high yields. Some of the allylic amines were converted in to the sulfonamide of (S)-phenylglycine without loss of enantiomeric purity by oxidative cleavage of the carbon-carbon double bond.

Full text of DOI:10.1016/S0040-4020(01)00075-8

TETRAHEDRON
Pergamon
Tetrahedron 57 (2001) 2589±2595
Rhodium-catalyzed asymmetric arylation of a,b-unsaturated
imines with arylstannanes. Catalytic asymmetric synthesis
of allylic amines
Tamio Hayaship and Mitsuo Ishigedani
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
Received 8 August 2000; revised 26 September 2000; accepted 29 September 2000
AbstractÐCatalytic asymmetric arylation of N-alkylidenesulfonamides 1a±d, which are prepared from a,b-unsaturated aldehydes and
4-nitrobenzenesulfonamide, with aryltrimethylstannanes 2m±p proceeded in the presence of 3 mol% of a rhodium catalyst coordinated with
(R)-MOP ligand in dioxane at 1108C to give sulfonamide of allylic amines (R)-3 with high enantioselectivity (up to 96% ee) in high yields.
Some of the allylic amines were converted in to the sulfonamide of (S)-phenylglycine without loss of enantiomeric purity by oxidative
cleavage of the carbon±carbon double bond. q 2001 Elsevier Science Ltd. All rights reserved.
1. Introduction
tivity (up to 96% ee) in high yields (Scheme 1).6 This asym-
metric reaction provides a new ef®cient route to optically
active diarylmethylamines, some of which are biologically
active compounds.7 Here we wish to report that imines of
a,b-unsaturated aldehydes also underwent the rhodium-
catalyzed asymmetric arylation on the carbon±nitrogen
double bond to give sulfonamides of allylic amines of
high enantiomeric purity, which can be readily converted
into arylglycines.
Enantiomerically pure allylic amines are important
molecules because of their synthetic utility as precursors
to a-amino acids as well as their biological activity, and
considerable efforts have been made to construct these
molecules by means of asymmetric catalysis.1 The stereo-
genic carbon center in the allylic amines is bonded to one
hydrogen atom, two alkyl carbon substituents, and one
amino group. Thus, the asymmetric synthesis of these
amines can be accomplished by enantioselective formation
of a new bond between either carbon±hydrogen, carbon±
carbon, or carbon±nitrogen bond on the stereogenic carbon
atom. The examples of the catalytic asymmetric reactions
which correspond to the enantioselective bond formation
described above are asymmetric reduction of imines derived
from unsymmetrical ketones,1±3 asymmetric addition of
organometallic reagents to imines of aldehydes,1,2 and
asymmetric allylic amination,1,4 respectively. Of these
methods, the asymmetric addition to imines is most inter-
esting because a new chiral carbon skeleton is created in a
catalytic enantioselective fashion. Unfortunately, however,
only a few examples have been reported where high
enantioselectivity is achieved in this type of carbon±carbon
bond forming reactions.5 We have previously reported that a
rhodium complex coordinated with chiral monodentate
phosphine (MOP) catalyzes asymmetric arylation of imines,
N-alkylidenesulfonamides, with arylstannanes to give
sulfonamide of diarylmethylamines with high enantioselec-
2. Results and discussion
Sulfonamides 1 were prepared by the reaction of a,b-
unsaturated aldehydes with 4-nitrobenzenesulfonamide in
the presence of tetraethoxysilane as a dehydrating reagent.8
The sulfonamide containing 4-nitro group was used because
the sulfonyl protecting group is readily removed from nitro-
gen by treatment with a thiophenoxide9 and the imine of
4-nitrobenzenesulfonamide was found to be more reactive
than other sulfonamides towards the rhodium-catalyzed
arylation in our previous studies.6 As R groups in a,b-
unsaturated imines 1, aryl groups were chosen because the
imines containing alkyl groups could not be isolated pure.
The phenylation of sulfonamide of (E)-3-phenyl-2-propenal
Keywords: catalytic asymmetric synthesis; rhodium catalysis; asymmetric
arylation; optically active allylamine; amino acid.
Corresponding author. Tel.: 181-75-753-3983; fax: 181-75-753-3988;
e-mail: thayashi@kuchem.kyoto-u.ac.jp
Scheme 1. Ar1, Ar2ˆPh, 4-CF3C6H4, 4-FC6H4, 4-ClC6H4, 4-MeOCOC6H4,
p
4-MeOC6H4.
0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(01)00075-8

2590
T. Hayashi, M. Ishigedani / Tetrahedron 57 (2001) 2589±2595
Scheme 2.
1a with phenyltrimethylstannane (2m) was carried out
under the reaction conditions which were used for the reac-
tion of sulfonamides of aromatic aldehydes.6 Thus, a
mixture of 1a, 2m (5 equiv. to 1a), lithium ¯uoride
(10 equiv.), and 3 mol% of the catalyst generated from
Rh(acac)(C2H4)2 and (R)-MeO±MOP in dioxane was heated
in a sealed tube at 1108C for 12 h. Aqueous work-up
followed by chromatography on a silica gel column with
ethyl acetate as an eluent gave 75% yield of the sulfonamide
of (E)-1,3-diphenyl-2-propenylamine 3am (Scheme 2). Its
enantiomeric purity was determined to be 88% ee by HPLC
analysis with a chiral stationary phase column (entry 1 in
Table 1), and the absolute con®guration was determined to
be (2)-(R) by correlation with (S)-phenylglycine (vide
infra). Under the present reaction conditions, the addition
proceeded in a 1,2-fashion exclusively, the 1,4-addition
product being not detected at all. The addition of lithium
¯uoride to the reaction mixture is not essential for the
phenylation reaction to proceed, but the reproducibility in
the chemical yield of 3am was higher in the presence of
lithium ¯uoride than in its absence. A higher enantioselec-
tivity (93% ee) was observed with (R)-Arp±MOP which
contains 3,5-dimethyl-4-methoxyphenyl group in place of
methoxy at the 20 position of the MOP ligand (entry 2). The
(R)-Arp±MOP was prepared in 58% yield by nickel-cata-
lyzed cross-coupling of the 3,5-dimethyl-4-methoxyphenyl
Grignard reagent with (R)-TfO±MOP10 which was obtained
from 2,20-dihydroxy-1,10-binaphthyl by a sequence of reac-
tions including palladium-catalyzed monophosphinylation
of binaphthyl ditri¯ate as a key step11,12 (Scheme 3).
The asymmetric arylation of imine 1a also proceeded with
phenylstannanes substituted at the para-position with elec-
tron-donating or electron-withdrawing groups 2n±p, though
the enantioselectivity was a little lower than that in the reac-
tion with unsubstituted phenylstannane 2m (entries 3±8). In
the reaction of imine 1a, Arp±MOP ligand always showed
higher enantioselectivity than MeO±MOP ligand (entries 1±8).
N-Alkylidenesulfonamides 1c and 1d, which were prepared
from a,b-unsaturated aldehydes containing two substituents at
the b-position, were also subjected to the rhodium-catalyzed
Table 1. Catalytic asymmetric arylation of imines 1 with arylstannanes 2 catalyzed by rhodium/(R)-MOP complexes
Entry
Imine 1
Ar in ArSnMe3 2
(R)-MOP
Yield (%)a of 3
% eeb of 3
[a]D20 (c in CHCl3)
1
2
3
4
5
6
7
8
1a
1a
1a
1a
1a
1a
1a
1a
1b
1b
1c
1c
1c
1c
1d
1d
Ph (2m)
Ph (2m)
MeO±MOP
Arp±MOP
MeO±MOP
Arp±MOP
MeO±MOP
Arp±MOP
MeO±MOP
Arp±MOP
MeO±MOP
Arp±MOP
MeO±MOP
Arp±MOP
MeO±MOP
Arp±MOP
MeO±MOP
Arp±MOP
75 (3am)
77 (3am)
68 (3an)
70 (3an)
67 (3ao)
67 (3ao)
46 (3ap)
63 (3ap)
65 (3bm)
74 (3bm)
80 (3cm)
92 (3cm)
79 (3cn)
95 (3cn)
82 (3dm)
93 (3dm)
88 (R)c
93 (R)c
52
79
74
80
68
90
92
215.9 (0.50)
24.0 (0.50)
27.1 (0.50)
217.3 (0.50)
29.8 (0.50)
2123 (0.50)
2154 (0.50)
265.8 (0.50)
4-MeOC6H4 (2n)
4-MeOC6H4 (2n)
4-MeC6H4 (2o)
4-MeC6H4 (2o)
4-CF3C6H4 (2p)
4-CF3C6H4 (2p)
Ph (2m)
Ph (2m)
Ph (2m)
Ph (2m)
9
10
11
12
13
14
15
16
89
95 (R)c
96 (R)c
90
4-MeOC6H4 (2n)
4-MeOC6H4 (2n)
Ph (2m)
96
95
96
Ph (2m)
The reaction was carried out in dioxane at 1108C for 12 h with 5 equiv. of 2 in the presence of LiF (10 equiv. to imine) and 3 mol% of the catalyst generated
from Rh(acac)(C2H4)2 and (R)-MOP.
Isolated yields by column chromatography on silica gel (pretreated with methanol and dried) using ethyl acetate as an eluent.
a
b
Determined by HPLC analysis with chiral stationary phase column, Daicel Chiralcel OD-H. Eluent: hexane/2-propanolˆ8/2 for 3am, 3ao, 3ap, and 3bm and
hexane/2-propanolˆ9/1 for 3an, 3cm, 3cn, and 3dm.
c
Determined by conversion into N-(4-nitrobenzenesulfonyl)phenylglycine methyl ester (4). See also text.

T. Hayashi, M. Ishigedani / Tetrahedron 57 (2001) 2589±2595
2591
Scheme 3.
asymmetric arylation (Scheme 4). The chemical yields of
the arylation products 3cm, cn and 3dm are generally very
high and the enantioselectivity was over 90%, higher than
that in the reaction of imines 1a and 1b (entries 11±16 in
Table 1). The enantioselectivity of 96% was observed in the
phenylation and 4-methoxyphenylation of 1c and 1d cata-
lyzed by the rhodium complex coordinated with Arp±MOP
ligand (entries 12, 14, and 16).
asymmetric addition of aryltin reagents can be successfully
applied to sulfonamides of a,b-unsaturated aldehydes. The
enantioselectivity was generally very high, over 90% ee in
the addition of phenyltrimethylstannane. The sulfonamides
of optically active allylic amines were readily converted in
to an a-amino acid derivative without loss of enantiomeric
purity by oxidative cleavage of the carbon±carbon double
bond.
The asymmetric phenylation products 3am and 3cm were
converted into a phenylglycine derivative by oxidation of
the carbon±carbon double bond. Thus, the oxidation of (2)-
3am (88% ee), obtained by the phenylation catalyzed by
rhodium/(R)-MeO±MOP (entry 1 in Table 1), with
ruthenium chloride and sodium periodate13 followed by
esteri®cation of the carboxylic acid with diazomethane
gave methyl N-4-nitrobenzenesulfonylphenylglycinate (4)
4. Experimental
4.1. General
All moisture sensitive manipulations were carried out under
a nitrogen atmosphere. Nitrogen gas was dried by passage
through P2O5. Optical rotations were recorded with a
JASCO DIP-370 polarimeter. NMR spectra were recorded
on a JEOL JNM LA500 spectrometer (500 MHz for 1H and
125 MHz for 13C) in CDCl3. Chemical shifts are reported in
whose speci®c rotation is [a]20 ˆ172.2 (c 1.0, chloro-
D
form). The authentic sample of (S)-4 prepared from (S)-
(1)-a-phenylglycine (100% ee) showed [a]20 ˆ177.6 (c
D
1
d ppm referenced to an internal SiMe4 standard for H
1.0, chloroform), indicating that the absolute con®guration
of (2)-3am is (R) and the oxidation proceeded without
signi®cant loss of the enantiomeric purity (Scheme 5).
The absolute con®guration of (2)-3cm was also determined
to be (R) by the conversion into (1)-(S)-4 in a similar
manner.
NMR. Residual chloroform (d 77.0 for 13C) was used as
internal reference for 13C NMR. HPLC analysis was
performed on a Shimadzu LC-9A and JASCO PU-980
liquid chromatograph system with chiral stationary phase
column, Daicel Chiralcel OD-H.
4.2. Materials
3. Conclusions
Tetrahydrofuran, 1,4-dioxane and diethyl ether were
distilled from benzophenone-ketyl under nitrogen prior to
In summary, we have shown that the rhodium-catalyzed
Scheme 4.
Scheme 5.

2592
T. Hayashi, M. Ishigedani / Tetrahedron 57 (2001) 2589±2595
use. Dichloromethane, 1,2-dimethoxyethane and dimethyl-
formamide were distilled from CaH2 under nitrogen. Dess±
Martin reagent,14 Rh(acac)(C2H4)2,15 and (R)-MeO±MOP12
were prepared according to the reported procedures.
acetone. The ®ltrate was stripped of solvent. The precipi-
tates formed were ®ltered off and washed with Et2O.
Removal of the solvent from the ®ltrate gave 3.07 g (75%
1
yield) of 9-¯uorenylidenemethanol: H NMR (CDCl3) d
1.81 (t, Jˆ5.9 Hz, 3H), 4.99 (t, Jˆ5.9 Hz, 2H), 6.81 (t,
Jˆ5.9 Hz, 1H), 7.27±7.40 (m, 4H), 7.60 (d, Jˆ7.9 Hz,
1H), 7.68 (t, Jˆ8.3 Hz, 2H), 7.73 (d, Jˆ7.4 Hz, 1H); 13C
NMR (CDCl3) d 60.57, 119.62, 119.97, 120.16, 125.19,
127.16, 127.17, 128.15, 128.41, 128.43, 136.05, 136.69,
138.75, 139.23, 141.08. To a solution of 9-¯uorenylidene-
methanol (1.46 g, 7 mmol) in CH2Cl2 was carefully added
Dess±Martin reagent (3.57 g, 8.4 mmol) in small portions.
After 24 h the solution was extracted with CH2Cl2 and the
extract was washed with 1 M NaOH solution, water and
brine, and dried over sodium sulfate. Evaporation of the
solvent gave 1.35 g (93% yield) of 9-¯uorenylidene-
acetaldehyde: 1H NMR (CDCl3) d 6.82 (d, Jˆ8.3 Hz,
1H), 7.29 (t, Jˆ7.4 Hz, 1H), 7.30 (t, Jˆ7.4 Hz, 1H), 7.42
(t, Jˆ7.4 Hz, 1H), 7.45 (t, Jˆ7.4 Hz, 1H), 7.62 (d, Jˆ
7.4 Hz, 1H), 7.66 (d, Jˆ7.4 Hz, 2H), 8.01 (d, Jˆ7.4 Hz,
1H), 10.84 (d, Jˆ8.3 Hz, 1H); 13C NMR (CDCl3) d
120.13, 120.48, 122.29, 122.94, 127.58, 127.95, 131.15,
131.39, 131.50, 135.51, 138.15, 141.09, 142.68, 151.22,
190.09.
4.3. Preparation of (R)-2-(diphenylphosphino)-20-(3,5-
dimethyl-4-methoxyphenyl)-1,10-binaphthyl (Arp±
MOP)
A mixture of (R)-2-(diphenylphosphino)-20-(tri¯uoromethane-
sulfonyloxy)-1,10-binaphthyl (1.12 g, 1.91 mmol), dichloro-
[1,3-bis(diphenylphosphino)propane]nickel (0.202 g, 0.38
mmol), and 3,5-dimethyl-4-methoxyphenylmagnesium
bromide (1.5 M, 9 mL, in tetrahydrofuran) was re¯uxed
for 24 h under nitrogen. After cooling to room temperature,
the reaction mixture was quenched with saturated ammo-
nium chloride (20 mL) on ice bath, and extracted with
diethyl ether. The extract was dried over anhydrous
MgSO4 and concentrated in vacuo. The residue was chro-
matographed on silica gel (hexane/ethyl acetateˆ5/1) to
give 0.634 g (58% yield) of (R)-2-(diphenylphosphino)-20-
(3,5-dimethyl-4-methoxyphenyl)-1,10-binaphthyl
(Arp±
MOP): [a]20 ˆ1183 (c 1.00, chloroform); 1H NMR
D
(CDCl3) d 1.83 (s, 6H), 3.61 (s, 3H), 6.61 (s, 2H), 6.65 (t,
Jˆ6.8 Hz, 2H), 6.83 (d, Jˆ8.3 Hz, 1H), 6.90 (t, Jˆ6.8 Hz,
2H), 7.00 (t, Jˆ7.3 Hz, 1H), 7.04 (t, Jˆ7.3 Hz, 2H), 7.09 (t,
Jˆ6.8 Hz, 2H), 7.12 (t, Jˆ7.8 Hz, 1H), 7.17 (t, Jˆ7.3 Hz,
1H), 7.22 (dd, Jˆ8.8, 2.9 Hz, 1H), 7.35 (t, Jˆ8.3 Hz, 1H),
7.36 (t, Jˆ3.9 Hz, 1H), 7.45 (d, Jˆ8.8 Hz, 1H), 7.50 (t, Jˆ
6.8 Hz, 1H), 7.63 (d, Jˆ8.3 Hz, 1H), 7.74 (d, Jˆ8.8 Hz,
1H), 7.86 (d, Jˆ8.3 Hz, 1H), 7.91 (d, Jˆ8.3 Hz, 1H), 8.03
(d, Jˆ8.3 Hz, 1H); 31P{1H}NMR d 219.54 (s). Anal. Calcd
for C41H33PO: C, 85.99; H, 5.81. Found: C, 85.71; H, 5.91.
4.5. Preparation of imines (1a±d)
Imines 1a±d were prepared according to the procedures
reported8 for the synthesis of imines by use of tetraethoxy-
silane as a dehydrating agent: a sulfonamide, an aldehyde
(1.0±1.1 equiv.), and tetraethoxysilane (1.1 equiv.) were
combined in a ¯ask equipped with a Dean±Stark, and the
mixture was heated at 1608C under nitrogen for 6 h. After
cooling to room temperature, the reaction mixture was
dissolved in warm ethyl acetate, treated with n-hexane,
and allowed to stand at room temperature. The crystals
were collected by ®ltration, washed with n-hexane, and
dried.
4.4. Preparation of 9-¯uorenylideneacetaldehyde
According to Wadsworth's procedures,16 9-¯uorenylidene-
acetaldehyde was prepared as follows: Triethyl phos-
phonoacetate (16.8 g, 75 mmol) was added dropwise at
208C to a slurry of 60% sodium hydride (3.0 g, 75 mmol)
in 1,2-dimethoxyethane (100 mL), and the mixture was
stirred at room temperature for 1 h. 9-Fluorenone (13.5 g,
75 mmol) was added dropwise to the solution and the
mixture was re¯uxed for 48 h. A large excess of water
was added, and the solution was extracted with ethyl
acetate. The extract was dried over magnesium sulfate and
concentrated in vacuo. The residue was chromatographed
on silica gel (hexane/ethyl acetate) to give 11.1 g (59%
4.5.1. N-[(E)-2-Phenylethenyl]methylidene-4-nitroben-
zenesulfonamide (1a). 1H NMR (CDCl3) d 7.01 (dd,
Jˆ15.5, 9.3 Hz, 1H), 7.43±7.51 (m, 3H), 7.58±7.62 (m,
3H), 8.17 (d, Jˆ8.8 Hz, 2H), 8.38 (d, Jˆ8.8 Hz, 2H), 8.86
(d, Jˆ9.3 Hz, 1H); 13C NMR (CDCl3) d 124.32, 124.37,
128.96, 129.23, 129.33, 132.26, 133.89, 144.50, 150.54,
155.91, 172.97. Anal. Calcd for C15H12O4N2S: C, 56.95;
H, 3.82. Found: C, 56.69; H, 3.85.
1
yield) of ethyl 9-¯uorenylideneacetate: H NMR (CDCl3)
4.5.2. N-[(E)-2-(4-Methoxyphenyl)ethenyl]methylidene-
4-nitrobenzenesulfonamide (1b). 1H NMR (CDCl3) d
3.87 (s, 3H), 6.88 (dd, Jˆ15.7, 9.8 Hz, 1H), 6.95 (d, Jˆ
8.8 Hz, 2H), 7.54 (d, Jˆ15.7 Hz, 2H), 7.55 (d, Jˆ8.8 Hz,
1H), 8.16 (d, Jˆ9.3 Hz, 2H), 8.37 (d, Jˆ9.3 Hz, 2H), 8.82
(d, Jˆ9.8 Hz, 1H); 13C NMR (CDCl3) d 55.59, 114.88,
121.95, 124.27, 126.82, 129.10, 131.13, 144.91, 150.44,
156.02, 163.19, 173.12. Anal. Calcd for C16H14O5N2S: C,
55.48; H, 4.07. Found: C, 55.35; H, 4.21.
d 1.39 (t, Jˆ7.4 Hz, 3H), 4.34 (q, Jˆ7.4 Hz, 2H), 6.74 (s,
1H), 7.25 (t, Jˆ7.4 Hz, 1H), 7.30 (t, Jˆ7.4 Hz, 1H), 7.37 (t,
Jˆ7.4 Hz, 1H), 7.39 (t, Jˆ7.4 Hz, 1H), 7.60 (d, Jˆ7.8 Hz,
1H), 7.62 (d, Jˆ8.3 Hz, 1H), 7.65 (d, Jˆ7.8 Hz, 1H), 8.89
(d, Jˆ8.3 Hz, 1H); 13C NMR (CDCl3) d 14.36, 60.67,
113.92, 119.54, 119.74, 121.22, 127.44, 128.03, 129.20,
130.52, 130.85, 135.19, 138.84, 140.74, 142.49, 148.23,
166.29. To a solution of ethyl 9-¯uorenylideneacetate
(5.00 g, 20 mmol) in toluene was added 40 mL of DIBAH
in toluene (1M solution) at 2788C. The mixture was stirred
at 2788C for 4 h, and sodium sulfate decahydrate was
added. It was diluted with n-hexane and sodium sulfate
was added. The mixture was kept stirring at room tempera-
ture for 1 h. The salts were ®ltered off and washed with
4.5.3. N-(2,2-Diphenylethenyl)methylidene-4-nitroben-
1
zenesulfonamide (1c). H NMR (CDCl3) d 6.94 (d, Jˆ
9.8 Hz, 1H), 7.24 (d, Jˆ7.9 Hz, 2H), 7.36 (d, Jˆ7.9 Hz,
2H), 7.40 (t, Jˆ7.9 Hz, 2H), 7.46 (t, Jˆ7.9 Hz, 1H), 7.49
(t, Jˆ7.9 Hz, 2H), 7.55 (t, Jˆ7.9 Hz, 1H), 8.12 (d, Jˆ

T. Hayashi, M. Ishigedani / Tetrahedron 57 (2001) 2589±2595
2593
8.8 Hz, 2H), 8.37 (d, Jˆ8.8 Hz, 2H), 8.65 (d, Jˆ9.8 Hz,
1H); 13C NMR (CDCl3) d 123.34, 124.22, 128.70, 128.75,
129.15, 129.18, 130.33, 130.65, 131.33, 136.54, 139.41,
144.53, 150.42, 166.77, 171.29. Anal. Calcd for
C21H16O4N2S: C, 64.27; H, 4.11. Found: C, 64.01; H, 4.24.
mide (127 mg, 0.40 mmol; 1a). The bottle was sealed under
nitrogen. The mixture was stirred at 1108C for 12 h and
concentrated in vacuo. The residue was dissolved in
dichloromethane, washed with water, dried over anhydrous
MgSO4, and evaporated. The residue was chromatographed
on a silica gel column (COSMOSIL 75SL-II-PREP,
18 mmf £30 mm, pretreated with methanol and dried)
with ethyl acetate as an eluent to give 119 mg (75% yield)
of 3am. Analytically pure sample was obtained by prepara-
tive thin-layer chromatography on silica gel (hexane/ethyl
acetateˆ2/1). Chiral stationary phase columns and eluents
used for the determination of enantiomeric purities of the
arylation products are shown in Table 1.
4.5.4. N-(9-Fluorenylidenemethyl)methylidene-4-nitro-
benzenesulfonamide (1d). H NMR (CD2Cl2) d 7.30 (d,
1
Jˆ10.8 Hz, 1H), 7.40 (t, Jˆ7.8 Hz, 1H), 7.47 (t, Jˆ
7.8 Hz, 1H), 7.56 (t, Jˆ7.4 Hz, 1H), 7.60 (t, Jˆ7.4 Hz,
1H), 7.74 (d, Jˆ7.4 Hz, 1H), 7.79 (d, Jˆ7.8 Hz, 1H), 7.81
(d, Jˆ7.8 Hz, 1H), 8.04 (d, Jˆ7.4 Hz, 1H), 8.31 (d, Jˆ
8.8 Hz, 2H), 8.50 (d, Jˆ8.8 Hz, 2H), 9.96 (d, Jˆ10.8 Hz,
1H); 13C NMR (CD2Cl2) d 110.98, 119.86, 120.73, 121.20,
123.20, 124.77, 127.84, 128.60, 128.68, 129.72, 132.50,
132.69, 135.52, 138.19, 141.72, 143.44, 155.88, 168.34.
Anal. Calcd for C21H14O4N2S: C, 64.61; H, 3.61. Found:
C, 64.33; H, 3.33.
4.7.1. N-[(E)-2-(Phenylethenyl)phenylmethyl]-4-nitro-
benzenesulfonamide (3am). [a]20 ˆ215.9 (c 0.50,
D
1
chloroform); H NMR (CDCl3) d 5.18 (s, 1H), 5.25 (t,
Jˆ6.9 Hz, 1H), 6.09 (dd, Jˆ15.5, 6.9 Hz, 1H), 6.41 (d,
Jˆ15.7 Hz, 1H), 7.16±7.21 (m, 4H), 7.22±7.29 (m, 6H),
7.85 (d, Jˆ8.8 Hz, 2H), 8.11 (d, Jˆ8.8 Hz, 2H); 13C NMR
(CDCl3) d 60.28, 123.92, 126.46, 127.11, 127.29, 128.33,
128.44, 128.45, 128.68, 128.91, 133.08, 135.46, 138.67,
146.67, 149.67. Anal. Calcd for C21H18O4N2S: C, 63.94;
H, 4.60. Found: C, 63.70; H, 4.65.
4.6. Preparation of arylstannanes (2m±p)
A typical procedure is given for the preparation of phenyl-
trimethylstannane (2m). A general procedure is shown
below: to a solution of trimethyltin chloride (7.97 g,
40.0 mmol) in 20 mL of THF was added phenylmagnesium
bromide (80 mL, 1.0 M THF solution, 80.0 mmol). The
mixture was re¯uxed for 1 h. After cooling to room
temperature, the reaction mixture was quenched with satu-
rated ammonium chloride (20 mL) on ice bath and extracted
with diethyl ether. The organic layer was washed with satu-
rated NaHCO3, dried over anhydrous MgSO4, and concen-
trated in vacuo. The residue was puri®ed by bulb-to-bulb
distillation under reduced pressure to give 9.62 g (quanti-
tative yield) of phenyltrimethylstannane.
4.7.2. N-[(E)-2-(Phenylethenyl)(4-methoxyphenyl)methyl]-
4-nitrobenzenesulfonamide (3an). [a]20 ˆ24.0 (c 0.50,
D
1
chloroform); H NMR (CDCl3) d 3.76 (s, 3H), 6.08 (dd,
Jˆ15.7, 6.9 Hz, 1H), 6.40 (d, Jˆ15.7 Hz, 1H), 6.76 (d,
Jˆ8.8 Hz, 2H), 7.09 (d, Jˆ8.8 Hz, 2H), 7.19 (d, Jˆ
7.9 Hz, 2H), 7.22±7.32 (m, 5H), 7.86 (d, Jˆ8.8 Hz, 2H),
8.14 (d, Jˆ8.8 Hz, 2H); 13C NMR (CDCl3) d 55.34, 59.78,
114.21, 123.90, 126.44, 127.51, 128.37, 128.39, 128.49,
128.67, 130.73, 132.77, 135.54, 146.76, 149.65, 159.57.
Anal. Calcd for C22H20O5N2S: C, 62.25; H, 4.75. Found:
C, 61.98; H, 4.59.
4.6.1. Phenyltrimethylstannane (2m). 1H NMR (CDCl3) d
0.28 (s, 9H), 7.33 (t, Jˆ6.9 Hz, 3H), 7.49 (d, Jˆ5.9 Hz, 2H).
4.6.2. 4-Methoxyphenyltrimethylstannane (2n). 1H NMR
(CDCl3) d 0.26 (s, 9H), 3.80 (s, 3H), 6.92 (d, Jˆ8.4 Hz,
2H), 7.40 (d, Jˆ8.4 Hz, 2H).
4.6.3. 4-Tolyltrimethylstannane (2o). 1H NMR (CDCl3) d
0.26 (s, 9H), 2.33 (s, 3H), 7.17 (d, Jˆ7.4 Hz, 2H), 7.39 (d,
Jˆ7.4 Hz, 2H).
4.7.3. N-[(E)-2-(Phenylethenyl)(4-tolyl)methyl]-4-nitro-
benzenesulfonamide (3ao). [a]20 ˆ27.1 (c 0.50, chloro-
D
form); 1H NMR (CDCl3) d 2.29 (s, 3H), 5.04 (d, Jˆ6.9 Hz,
1H), 5.20 (t, Jˆ6.9 Hz, 1H), 6.08 (dd, Jˆ16.1, 6.9 Hz, 1H),
6.41 (d, Jˆ15.7 Hz, 1H), 7.04 (s, 4H), 7.17±7.30 (m, 5H),
7.85 (d, Jˆ8.8 Hz, 2H), 8.12 (d, Jˆ8.8 Hz, 2H); 13C NMR
(CDCl3) d 20.96, 60.02, 123.82, 126.40, 126.99, 127.48,
128.29, 128.41, 128.59, 129.08, 129.43, 132.69, 135.53,
138.19, 146.65, 149.53. Anal. Calcd for C22H20O4N2S: C,
64.69; H, 4.94. Found: C, 64.40; H, 4.86.
4.6.4. 4-Tri¯uoromethylphenyltrimethylstannane (2p).
1H NMR (CDCl3) d 0.32 (s, 9H), 7.55 (d, Jˆ7.3 Hz, 2H),
7.61 (d, Jˆ7.3 Hz, 2H).
4.7.4. N-[(E)-2-(Phenylethenyl)(4-tri¯uoromethylphenyl)-
methyl]-4-nitrobenzenesulfonamide (3ap). [a]20 ˆ217.3
D
1
(c 0.50, chloroform); H NMR (CDCl3) d 5.03 (d, Jˆ
4.7. Rhodium-catalyzed asymmetric arylation of imines
with organostannanes (3am, 3an, 3ao, 3ap, 3bm, 3cm,
3cn, 3dm)
6.9 Hz, 1H), 5.31 (t, Jˆ6.9 Hz, 1H), 6.05 (dd, Jˆ15.7,
7.3 Hz, 1H), 6.40 (d, Jˆ15.7 Hz, 2H), 7.19 (d, Jˆ7.8 Hz,
2H), 7.23±7.28 (m, 2H), 7.36 (d, Jˆ7.8 Hz, 2H), 7.53 (d,
Jˆ7.8 Hz, 2H), 7.88 (d, Jˆ8.8 Hz, 2H), 8.17 (d, Jˆ8.8 Hz,
2H); 13C NMR (CDCl3) d 59.85, 123.62 (q, Jˆ272 Hz),
124.41, 125.77 (q, Jˆ3.6 Hz), 126.19, 126.50, 127.58,
128.40, 128.73, 128.75, 130.48 (q, Jˆ33 Hz), 133.82,
135.09, 142.77, 146.30, 149.79. Anal. Calcd for
C22H17O4N2SF3: C, 57.14; H, 3.71. Found: C, 56.88; H,
3.65.
The reactions conditions and results are summarized in
Table 1. A typical procedure is given for the preparation
of N-[(E)-2-phenylethenyl)phenylmethyl]-4-nitrobenzene-
sulfonamide (3am) (entry 1, Table 1): Phenyltrimethyl-
stannane (482 mg, 2.00 mmol) and 1,4-dioxane (0.6 mL)
were added to a pressure bottle charged with lithium
¯uoride (104 mg, 4.00 mmol), Rh(acac)(C2H4)2 (3.1 mg,
12 mmol), (R)-MeO±MOP (12.4 mg, 26 mmol), and
N-[(E)-2-Phenylethenyl]methylidene-4-nitrobenzenesulfona-
4.7.5. N-[(E)-2-(4-Methoxyphenylethenyl)phenylmethyl]-

2594
T. Hayashi, M. Ishigedani / Tetrahedron 57 (2001) 2589±2595
4-nitrobenzenesulfonamide (3bm)[a]20 ˆ29.8 (c 0.50,
bicarbonate solution. The basic extracts were acidi®ed to
pH 2 using 2 M HCl and extracted three times with Et2O.
The extracts were dried over anhydrous MgSO4 and concen-
trated in vacuo. The residue was dissolved in Et2O. Excess
ethereal diazomethane was added and the mixture was
stirred at room temperature for 1 h. Acetic acid was added
to quench excess diazomethane and the solvent was evapo-
rated. The residue was chromatographed by preparative
TLC on silica gel (benzene/ethyl acetateˆ5/1) to give
41 mg (39% yield) of methyl N-4-nitrobenzenesulfonyl-
phenylglycinate (4). Ester 4 was prepared from 3cm
(188 mg, 0.40 mmol, 96% ee) by a similar method to give
D
1
chloroform); H NMR (CDCl3) d 3.79 (s, 3H), 5.10 (d,
Jˆ6.9 Hz, 1H), 5.22 (t, Jˆ6.9 Hz, 1H), 5.93 (dd, Jˆ15.7,
6.9 Hz, 1H), 6.34 (d, Jˆ15.7 Hz, 1H), 6.79 (d, Jˆ8.8 Hz,
2H), 7.12 (d, Jˆ8.8 Hz, 2H), 7.17 (d, Jˆ6.9 Hz, 2H), 7.22±
7.26 (m, 3H), 7.84 (d, Jˆ8.8 Hz, 2H), 8.10 (d, Jˆ8.8 Hz,
2H); 13C NMR (CDCl3) d 55.32, 60.44, 114.07, 123.88,
125.06, 127.09, 127.73, 128.17, 128.43, 128.65, 128.82,
132.56, 138.92, 146.70, 149.59, 159.79. Anal. Calcd for
C22H20O5N2S: C, 62.25; H, 4.75. Found: C, 62.00; H, 4.53.
4.7.6. N-[(2,2-Diphenylethenyl)phenylmethyl]-4-nitro-
benzenesulfonamide (3cm). [a]20 ˆ2123 (c 0.50, chloro-
90 mg (26% yield): [a]20 ˆ172.2 (c 1.00, chloroform) [A
D
D
form); 1H NMR (CDCl3) d 4.94 (d, Jˆ5.4 Hz, 1H), 5.08 (dd,
Jˆ9.8, 5.4 Hz, 1H), 6.03 (d, Jˆ9.8 Hz, 1H), 7.03 (t, Jˆ
9.3 Hz, 4H), 7.15±7.40 (m, 11H), 7.75 (d, Jˆ8.8 Hz, 2H),
8.14 (d, Jˆ8.8 Hz, 2H); 13C NMR (CDCl3) d 57.12, 123.94,
125.95, 127.09, 127.45, 128.07, 128.13, 128.18, 128.20,
128.36, 128.41, 128.94, 129.45, 138.11, 139.62, 140.85,
144.36, 146.22, 149.67. Anal. Calcd for C27H22O5N2S: C,
68.92; H, 4.71. Found: C, 68.95; H, 4.65.
sample prepared from 3cm gave [a]20 ˆ173.7 (c 1.00,
D
1
chloroform)]; H NMR (CDCl3) d 3.66 (s, 3H), 5.18 (d,
Jˆ6.9 Hz, 1H), 5.89 (d, Jˆ6.9 Hz, 1H), 7.15 (d, Jˆ
7.4 Hz, 2H), 7.20 (t, Jˆ7.4 Hz, 2H), 7.25 (t, Jˆ6.9 Hz,
1H), 7.78 (d, Jˆ8.8 Hz, 2H), 8.14 (d, Jˆ8.8 Hz, 2H); 13C
NMR (CDCl3) d 53.37, 59.54, 123.90, 127.39, 128.23,
128.95, 129.02, 134.51, 146.09, 149.79, 170.11. Anal.
Calcd for C15H14O6N2S: C, 51.42; H, 4.03. Found: C,
51.69; H, 4.21.
4.7.7. N-[(2,2-Diphenylethenyl)(4-methoxyphenyl)methyl]-
4-nitrobenzenesulfonamide (3cn). [a]20 ˆ2154 (c 0.50,
D
4.9. Preparation of methyl N-4-nitrobenzenesulfonyl-
phenylglycinate (4) from (S)-(1)-a-phenylglycine
1
chloroform); H NMR (CDCl3) d 3.77 (s, 3H), 5.00 (dd,
Jˆ9.3, 5.9 Hz, 1H), 5.22 (d, Jˆ5.9 Hz, 1H), 6.01 (d, Jˆ
9.8 Hz, 1H), 6.78 (d, Jˆ8.8 Hz, 2H), 6.98±7.04 (m, 4H),
7.09 (d, Jˆ8.8 Hz, 2H), 7.20±7.25 (m, 3H), 7.33±7.38 (m,
3H), 7.75 (d, Jˆ8.8 Hz, 2H), 8.14 (d, Jˆ8.8 Hz, 2H); 13C
NMR (CDCl3) d 55.32, 56.65, 114.32, 123.96, 126.26,
127.50, 128.08, 128.13, 128.23, 128.38, 128.41, 128.45,
129.52, 131.70, 138.21, 140.98, 144.08, 146.36, 149.74,
159.50. Anal. Calcd for C28H24O5N2S: C, 67.18; H, 4.83.
Found: C, 67.06; H, 4.73.
(S)-(1)-a-Phenylglycine (44 mg, 0.40 mmol) was sus-
pended in 10 mL of dimethoxypropane, and to the suspen-
sion was added 1 mL of 36% aqueous hydrochloric acid.
The mixture was stirred at 208C for 18 h before the solvent
was evaporated. Recrystallization of the residue from
methanol±ether gave 193 mg (94% yield) of methyl phenyl-
glycinate hydrochloride.18 To a suspension of methyl
phenylglycinate hydrochloride (81 mg, 0.4 mmol) in tetra-
hydrofuran (3.0 mL) were added 4-nitrobenzenesulfonyl
chloride (106 mg, 0.48 mmol), triethylamine (97 mg, 0.96
mmol), and 4-dimethylaminopyridine (3.0 mg, 24 mmol),
and the mixture was stirred at 208C for 14 h. The mixture
was quenched with saturated citric acid solution and
extracted with ethyl acetate. Combined organic extracts
were washed with saturated sodium bicarbonate solution,
dried over magnesium sulfate, and concentrated under
reduced pressure. The residue was chromatographed on
silica gel (preparative thin-layer, benzene/ethyl acetateˆ
5/1) to give 80 mg (57% yield) of methyl N-4-nitrobenz-
4.7.8. N-[(9-Fluorenylidenemethyl)phenylmethyl]-4-nitro-
benzenesulfonamide (3dm). [a]20 ˆ265.8 (c 0.50,
D
1
chloroform); H NMR (CDCl3) d 5.32 (d, Jˆ7.3 Hz, 1H),
6.14 (d, Jˆ9.6 Hz, 1H), 6.22 (dd, Jˆ9.6, 7.3 Hz, 1H), 7.16
(t, Jˆ7.4 Hz, 1H), 7.24 (d, Jˆ7.8 Hz, 1H), 7.27±7.37 (m,
5H), 7.41 (t, Jˆ7.4 Hz, 1H), 7.44 (d, Jˆ7.8 Hz, 2H), 7.62
(d, Jˆ7.8 Hz, 1H), 7.67 (d, Jˆ8.8 Hz, 2H), 7.71 (d, Jˆ
7.4 Hz, 1H), 7.72 (d, Jˆ7.8 Hz, 1H), 7.78 (d, Jˆ8.8 Hz,
2H); 13C NMR (CDCl3) d 55.79, 100.58, 119.86, 120.24,
123.63, 124.69, 124.98, 127.01, 127.18, 127.63, 128.32,
128.64, 129.13, 129.17, 129.49, 135.59, 137.88, 138.03,
138.04, 139.03, 141.47. 145.96, 149.29. Anal. Calcd for
C27H20O4N2S: C, 69.22; H, 4.30. Found: C, 69.34; H, 4.04.
enesulfonylphenylglycinate (4): [a]20 ˆ177.6 (c 1.00,
D
chloroform).
4.8. Conversion of N-[(E)-2-(phenylethenyl)phenyl-
methyl]-4-nitrobenzenesulfonamide (3am) and N-[(2,2-
diphenylethenyl)phenylmethyl]-4-nitrobenzene-
sulfonamide (3cm) into methyl N-4-nitrobenzene-
sulfonylphenylglycinate (4)
Acknowledgements
This work was supported by `Research for the Future'
Program, the Japan Society for the Promotion of Science
and a Grant-in-Aid for Scienti®c Research, the Ministry of
Education, Japan.
The oxidation was carried out according to the reported
procedures:13,17 to a solution of 3am (118 mg, 0.30 mmol,
88% ee) in carbon tetrachloride (0.6 mL), acetonitrile
(0.6 mL), and water (0.9 mL) was added sodium meta-
periodate (263 mg, 1.23 mmol) and ruthenium trichloride
hydrate (3.5 mg, 2.2 mol%). After the solution was stirred
vigorously at 208C for 18 h, the reaction mixture was diluted
with Et2O and extracted twice with saturated sodium
References
1. For reviews on asymmetric catalysis, (a) Ojima, I. Catalytic
Asymmetric Synthesis; 2nd ed.; Wiley-VCH: New York, 2000.
(b) Noyori, R. Asymmetric Catalysis in Organic Synthesis;
Wiley: New York, 1994. (c) Jacobsen, E. N.; Pfaltz, A.;

T. Hayashi, M. Ishigedani / Tetrahedron 57 (2001) 2589±2595
2595
Yamamoto, H. Comprehensive Asymmetric Catalysis;
Springer: Berlin, 1999.
10. (a) Cho, S.-Y.; Shibasaki, M. Tetrahedron Lett. 1998, 39,
1773. (b) Gladiali, S.; Pulacchini, S.; Fabbri, D.; Manassero,
M.; Sansoni, M. Tetrahedron: Asymmetry 1998, 9, 391.
11. Kurz, L.; Lee, G.; Morgans, Jr., D.; Waldyke, M. J.; Wars, T.
Tetrahedron Lett. 1990, 31, 6321.
2. Kobayashi, S.; Ishitani, H. Chem. Rev. 1999, 99, 1069.
3. Blaser, H.-U.; Spindler, F. In Comprehensive Asymmetric
Catalysis; Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds.;
Springer: Berlin, 1999; Vol. 1, Chapter 6.2.
12. (a) Uozumi, Y.; Hayashi, T. J. Am. Chem. Soc. 1991, 113,
9887. (b) Uozumi, Y.; Tanahashi, A.; Lee, S.-Y.; Hayashi,
T. J. Org. Chem. 1993, 58, 1945. (c) Uozumi, Y.; Suzuki,
N.; Ogiwara, A.; Hayashi, T. Tetrahedron 1994, 50, 4293.
13. Carlsen, H. J.; Katsuki, T.; Martin, V. S.; Sharpless, K. B. J.
Org. Chem. 1981, 46, 3936.
4. Pfaltz, A.; Lautens, M. In Comprehensive Asymmetric Cata-
lysis; Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds.;
Springer: Berlin, 1999; Vol. 2, Chapter 24.
Â
5. (a) Gittins (nee Jones), C. A.; North, M Tetrahedron: Asym-
metry 1997, 8, 3789. (b) Denmark, S. E.; Nakajima, N.;
Nicaise, O. J.-C. J. Am. Chem. Soc. 1994, 116, 8797.
6. Hayashi, T.; Ishigedani, M. J. Am. Chem. Soc. 2000, 122, 976.
7. For examples: (a) Bishop, M. J.; McNutt, R. W. Bioorg. Med.
Chem. Lett. 1995, 5, 1311. (b) Spencer, C. M.; Foulds, D.;
Peters, D. H. Drugs 1993, 46, 1055. (c) Sakurai, S.; Ogawa,
N.; Suzuki, T.; Kato, K; Ohashi, T.; Yasuda, S.; Kato, H.; Ito,
Y. Chem. Pharm. Bull. 1996, 44, 765.
14. (a) Dess, D. B.; Martin, J. C. J. Am. Chem. Soc. 1991, 113,
7277. (b) Ireland, R. E.; Liu, L. J. Org. Chem. 1993, 58, 2899.
15. Cramer, R. Inorg. Synth. 1974, 15, 16.
16. Wadsworth, W. S.; Emmons, W. D. J. Am. Chem. Soc. 1961,
83, 1733.
17. Hayashi, T.; Yamamoto, A.; Ito, Y.; Nishioka, E.; Miura, H.;
Yanagi, K. J. Am. Chem. Soc. 1989, 111, 6301.
18. Rachele, J. R. J. Org. Chem. 1963, 28, 2898.
8. Love, B. E.; Raje, P. S.; Williams II, T. C. Synlett 1994, 493.
9. Fukuyama, T.; Jow, C.-K.; Cheung, M. Tetrahedron Lett.
1995, 36, 6373.