Chiral rare earth metal complex-catalyzed conjugate addition of O-alkylhydroxylamines. An efficient synthetic entry into optically active 2-acyl aziridines

Article abstract of DOI:10.1016/S0040-4020(02)00983-3

The conjugate addition of O-alkylhydroxylamines to α,β-unsaturated ketones is effectively catalyzed by chiral rare earth metal complexes to afford the corresponding β-amino ketones with high enantioselectivities (up to 99% ee) in almost quantitative yields, which are, upon treatment with a base catalyst, quantitatively converted into the 2-acyl aziridines without losing their enantiopurities. The protocol is highly practical thus providing an easy access to enantiopure 2-acyl aziridines and their derivatives in good quantities.

Full text of DOI:10.1016/S0040-4020(02)00983-3

Tetrahedron 58 (2002) 8321–8329
Chiral rare earth metal complex-catalyzed conjugate addition of
O-alkylhydroxylamines. An efficient synthetic entry into optically
active 2-acyl aziridines
Xiu Lan Jin, Hiroyasu Sugihara, Kazuhiro Daikai, Hiroki Tateishi, Yong Zhi Jin, Hiroshi Furuno
*
and Junji Inanaga
Institute for Fundamental Research of Organic Chemistry (IFOC), Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
Received 28 May 2002; accepted 4 June 2002
Abstract—The conjugate addition of O-alkylhydroxylamines to a,b-unsaturated ketones is effectively catalyzed by chiral rare earth metal
complexes to afford the corresponding b-amino ketones with high enantioselectivities (up to 99% ee) in almost quantitative yields, which are,
upon treatment with a base catalyst, quantitatively converted into the 2-acyl aziridines without losing their enantiopurities. The protocol is
highly practical thus providing an easy access to enantiopure 2-acyl aziridines and their derivatives in good quantities. q 2002 Elsevier
Science Ltd. All rights reserved.
1. Introduction
One of the interesting properties of rare earth metal ions is
their inherent strong Lewis acidities. A variety of rare earth
metal salts of strong acids like the triflates,1 perfluoro-
alkylsulfonates,2 – 4 perchlorates,2 bis(perfluoroalkylsul-
fonyl)amides,5 and tris(perfluoroalkylsulfonyl)methides6
have so far been prepared and successfully used in organic
synthesis as an effective Lewis acid catalyst.7 They are not
Figure 1.
only barely hydrolyzed under neutral or weakly acidic
conditions, but also sometimes work as an efficient catalyst
in the presence of water, alcohols, or even amines, although
under similar circumstances, most traditional Lewis acids
lose their activities.
corresponding b-amino ketones with high enantioselectivities
(up to 99% ee).
Recently, we prepared the 1:3 complexes of a series of
trivalent rare earth metal ions with chiral phosphate ligands,
RE[(R)-BNP]3 (RE¼rare earth; BNP¼1,10-binapphthyl-
2,20-diyl phosphate; Fig. 1), as isolable chiral Lewis acids
and demonstrated their usefulness for the enantioselective
hetero-Diels–Alder reaction.8 In the present study, we
examined their catalytic abilities for the Michael reaction
using amine nucleophiles and found that the chiral scandium
complex, Sc[(R)-BNP]3 (B-Sc, Fig. 1), can be an effective
catalyst for the conjugate addition of O-alkylhydroxyl-
amines to a,b-unsaturated ketones thus producing the
2. Results and discussion
Recently, we developed a practical and highly enantio-
selective epoxidation of conjugated enones using a La(O-i-
Pr)3 –(R)-BINOL–Ph3PO (1:1:3) precatalyst system
(BINOL¼1,10-bi-2-naphthol).9,10 From the analogy with
the epoxidation, we first applied the same precatalyst system
to the aziridination of chalcone 1a using O-methylhydroxyl-
amine 3 in place of an alkyl hydroperoxide (Scheme 1).
Although the chiral lanthanum complex in-situ prepared
from La(O-i-Pr)3, (R)-BINOL and Ph3PO (1:1:3) or La(O-i-
Pr)3, (R)-BINOL and Et3N (1:1:3) promoted the desired
reaction with notable enantioselectivities (38% and 72% ee,
respectively), the yields of the aziridine did not exceed the
amount of the complex used.11–14 Therefore, we turned our
attention to a stepwise process, the Lewis acid-catalyzed
Keywords: O-alkylhydroxylamines; 2-acyl aziridine; chiral rare earth metal
complex; asymmetric catalysis; asymmetric amplification.
*
Corresponding author. Tel.: þ81-92-642-2733; fax: þ81-92-642-2715;
e-mail: inanaga@ms.ifoc.kyushu-u.ac.jp
0040–4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(02)00983-3

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X. L. Jin et al. / Tetrahedron 58 (2002) 8321–8329
Table 2. Sc[(R)-BNP]3-catalyzed asymmetric Michael addition of O-
alkylhydroxylamine to 1a
Entry
R
Nucleophile/adduct
Yield (%)a
Ee (%)b
1
2
3
Me
Bn
Ph2CH
3/7a
5/8a
6/9a
81
94
94
57
91
99
Scheme 1.
The reaction was carried out for 18–24 h under argon in the presence of
10 mol% of B-Sc.
a
Isolated yield.
Ee of the crude product determined by the HPLC analysis using chiral
column.
b
complexes promoted the reaction at room temperature, but
the observed enantioselectivities were very low.
We then applied the RE[(R)-BNP]3 complex (B-RE, Fig. 1)
to the above reaction as a catalyst. As shown in Table 1,
among the complexes tested, Sc[(R)-BNP]3 (B-Sc) was
found to be the most effective. Thus, the reaction catalyzed
by B-Sc in toluene afforded the corresponding b-methoxy-
amino ketone 7a in good yield with modest enantio-
selectivity (57% ee) (entry 7). A higher enantioselectivity
(69% ee) was obtained by lowering the reaction temperature
to 2208C (entry 8), but the use of 2,6-lutidine8a or
molecular sieves 4A as an additive did not improve either
the chemical or optical yields.
Scheme 2.
enantioselective Michael addition15 followed by the base-
catalyzed aziridine ring formation (Scheme 2).16,17
2.1. Chiral Lewis acid-catalyzed asymmetric Michael
reaction
The rare earth metal triflate-based chiral complexes (A-RE,
Fig. 1),18 prepared in-situ from RE(OTf)3, (R)-BINOL, and
N,N-diisopropylethylamine (1:1:2) in an appropriate
solvent, were initially examined as a chiral Lewis-acid
catalyst for the Michael addition of 3 to 1a under various
conditions. Some selected results are summarized in Table 1.
As can be seen in entries 1–3, the scandium and lanthanum
We further found that the use of O-benzylhydroxylamine 5
or O-diphenylmethylhydroxylamine 619 as an amine
nucleophile was particularly effective (Table 2). Thus, an
almost perfect enantioselectivity (99% ee) was attained at
room temperature when 6 was employed (entry 3). The
p–p interaction between the phenyl groups of the amine
nucleophiles and that of the catalyst may be anticipated
because the decrease in the reaction rate due to the bulkiness
of the nucleophiles was not significant.
Table 1. Asymmetric Michael addition of 3 to 1a
The optimized protocol, i.e. the use of the B-Sc catalyst and
O-diphenylmethylhydroxylamine in toluene, was found to
be quite effective for other substrates as shown in Table 3.
Entry
Catalyst
Solvent
THF
Toluene
THF
Yield (%)a
Ee (%)b
1
2
3
4
5
6
A-Sc
A-Sc
A-La
A-La
A-Yb
A-Yb
B-Sc
B-Sc
B-Sc
B-Sc
B-Sc
B-Sc
B-Sc
B-Sc
B-La
B-Yb
74
64
66
30
18
14
81
80
67
42
44
50
36
59
33
57
3
Table 3. Sc[(R)-BNP]3-catalyzed asymmetric Michael addition of 6 to
conjugated enones 1
14
12
14
8
Toluene
THF
Toluene
Toluene
Toluene
m-(CF3)2Ph
PhCl
PhOMe
CH2Cl2
AcOEt
CH3CN
Toluene
Toluene
2
7
57
69
53
39
60
33
30
12
6
8c
9
Entry
R
1/9
Reaction time (h)
Ee (%)a
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
Ph
1a/9a
1b/9b
1c/9c
1d/9d
1e/9e
1f/9f
1g/9g
1h/9h
1i/9i
48
96
133
48
72
24
24
16
72
99
98
94
99
98
98
94
99
98
4-MePh
4-MeOPh
4-ClPh
3-ClPh
4-FPh
4-CNPh
4-NO2Ph
i-Pr
31
The reaction was carried out at room temperature for 14–18 h under argon
in the presence of 10 mol% of the catalyst unless otherwise noted. 1.0–
1.2 equiv. of 3 was used.
a
10 mol% of B-Sc was used. Isolated yield was .98%.
Ee of the crude product determined by the HPLC analysis using chiral
column.
Isolated yield.
Determined by the HPLC analysis using chiral column.
The reaction was carried out at 2208C for 72 h.
a
b
c

X. L. Jin et al. / Tetrahedron 58 (2002) 8321–8329
8323
The phenyl group of 1 was adopted in the hope that the
phenyl ketone would provide (1) high crystallinity, (2) no
oxime formation,16 and (3) an easy access to the ester group
if required. Actually, the desired b-amino ketones (9) were
quantitatively obtained in excellent ee values, and simple
recrystallization of the crude products easily afforded the
enantiopure compounds.
Figure 3.
strong Lewis acidity of the lanthanoid ions would be
effective for the activation of the N–OMe bond through
double coordination of the oxygen and nitrogen atoms as
shown in Fig. 3. As expected, when 10 mol% of La(O-i-Pr)3
or Yb(O-i-Pr)3 was employed as a catalyst, the desired ring
formation was completed within 4 h at room temperature to
give the 2-acyl aziridine 4a in 99% isolated yield. Any loss
in the optical purity of 7a or the retro-Michael reaction
leading back to the chalcone 1a was not detected.
2.2. Asymmetric amplification (positive nonlinear effect)
Since Kagan’s first report regarding the positive nonlinear
effect, such an asymmetric amplification has frequently
been observed in various catalytic asymmetric reactions,
especially using chiral metal complexes.20–22 However,
most of them are limited within the range of Kagan’s ML2
model (L¼chiral ligand),22a and a high degree of asym-
metric amplification concerning the ML3 system has not
been reported until we found such a phenomenon in the
Yb(BNP)3-catalyzed hetero-Diels–Alder reaction.8b As
expected, the reaction of 1h with 6 using the enantio-
merically impure scandium catalyst showed a remarkably
high asymmetric amplification as shown in Fig. 2. For
example, 9h with 97% ee was obtained using the catalyst
with 50% ee. The observed positive nonlinear effect
suggests that the active catalyst may not be monomeric
but rather dimeric or oligomeric, and it may also be
explained by the formation of thermodynamically stable
heterochiral complexes having almost no catalytic activity
as previously discussed in detail.8b
At this stage, we postulated that if the two OR groups on the
metal ion in Fig. 3 are chiral, there must be a difference in
the cyclization speed of the two enantiomers, (R)-7a and
(S)-7a. We then investigated the kinetic resolution of 7a
using a chiral lanthanum alkoxide catalyst prepared in situ
from 10 mol% each of La(O-i-Pr)3 and (R)-BINOL in the
presence of molecular sieves 4A. These results are shown in
Table 4; 16% yield (maximum 50% in theory) of (R)-7a
with 93% ee was recovered starting from rac-7a after the
48 h reaction.
Based on these results, (S)-enriched 7a (69% ee, cf. entry 8
in Table 1) was treated with the La(O-i-Pr)3–(S)-BINOL
catalyst and after a 28% conversion, the ee of the recovered
(S)-7a reached 86% (Scheme 3).
2.3. Base-catalyzed aziridine ring formation
In a preliminary experiment, the b-methoxyamino ketone
7a was first treated with 10 mol% of sodium methoxide in
THF at room temperature for 24 h. Unfortunately, the
aziridine ring formation did not cleanly proceed thus
affording the corresponding 4a in 62% isolated yield.17
We anticipated that the high coordination number and
Despite these findings, the dehydroalkoxylation of the
O-diphenylmethoxyamino ketone 9a could not cleanly be
converted into the aziridine ketone 4a by the catalysis with
La(O-i-Pr)3. The bulkiness of the diphenylmethyl group
might be responsible for this inefficiency; the N–O bond
activation anticipated in Fig. 3 may no longer be possible
Table 4. La(O-i-Pr)3-(R)-BINOL complex-catalyzed kinetic resolution of
racemic 7a
Entry
Time (h)
Conversion (%)
Ee of 4a (%)a
Ee of 7a (%)a
1
2
3
3
20
48
25
78
84
48
22
10
18
74
93
Ten mol% each of La(O-i-Pr)3 and (R)-BINOL was used.
a
Determined by the HPLC analysis using chiral column.
Scheme 3. La(O-i-Pr)3–(S)-BINOL complex-catalyzed kinetic resolution
of (S)-enriched 7a.
Figure 2. Asymmetric amplification observed in the Sc[(R)-BNP]3-
catalyzed Michael addition of 6 to 1h.

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X. L. Jin et al. / Tetrahedron 58 (2002) 8321–8329
Figure 4.
Table 5. Aziridine ring formation using base catalyst
Scheme 5. The synthesis of (aR,bS)-4a. (a) La(O-i-Pr)3-(R)-BINOL (1:1,
5 mol%), Ph3PO (15 mol%), 0.5 h, 99%. (b) 5 h, 39%. (c) 4 h, 66%.
Entry
Base/(mol%)
Reaction time (h)
Yield (%)a
1
2
3
4
5
6
7
8
9
La(O-i-Pr)3/10
Sm(O-i-Pr)3/10
Yb(O-i-Pr)3/10
NaOMe/100
NaO-i-Pr/10
NaO-t-Bu/5
NaO-t-Bu/10
NaO-t-Bu/50
DBUd/10
24
48
48
48
17
20
2
43
14
14
62
46b
.99
.99
.99
NRe
Instant.c
24
a
Isolated yield.
Benzophenone was also yielded.
The reaction completed instantaneously.
1,8-Diazabicyclo[5,4,0]undec-7-ene.
No reaction.
b
c
d
e
due to the steric repulsion shown in Fig. 4. After some
unsuccessful trials, we finally found that the catalytic
conversion of 9a to 4a was best performed using NaO-t-
Bu.17 Thus, the reaction was completed within 2 h at room
temperature and 4a was obtained in quantitative yield
without racemization (Table 5). Other bases like NaOMe or
NaO-i-Pr were found to be much less effective. For
example, in the case of NaO-i-Pr, 4a was isolated in 46%
yield and a significant amount of benzophenone was
detected, which might be derived from sodium diphenyl-
methoxide via the Meerwein–Pondrof–Verley–
Oppennauer process. Organic bases such as DBU did not
promote the desired reaction at all.
Figure 5. The ORTEP drawing of 10.
using an efficient catalyst system recently developed in this
laboratory,9 according to the literature methods (Scheme
5).23 The structure of the (aS,bS)-a-hydroxy-b-azido
ketone 10 was unambiguously determined by an X-ray
crystallographic analysis (Fig. 5).
3. Conclusion
Other substrates 9b–i were also quantitatively converted
into the corresponding 2-acyl aziridines 4b–i without losing
their enantiopurities (Scheme 4).
The chiral scandium complex, Sc[(R)-BNP]3, was found to
be an excellent Lewis acid catalyst for the conjugate
addition of O-diphenylmehylhydroxylamine to a,b-unsatu-
rated ketones thus affording the corresponding b-amino
ketones with high ee values (up to 99% ee) in almost
quantitative yields. A remarkably high asymmetric ampli-
fication (positive nonlinear effect) was observed in this
reaction. It was also found that the chiral lanthanum
complex prepared in-situ from La(O-i-Pr)3 and (S)-
BINOL, La[(S)-binaphthoxide·(O-i-Pr)], brought about
kinetic resolution of a racemic b-methoxyamino ketone in
the dehydromethoxylation step. The aziridine ring-
forming reaction of the b-diphenylmethoxyamino ketones
could be best performed using a catalytic amount of NaO-t-
Bu. The catalytic two-step process is so convenient and
efficient that the protocol provides an easy access to
enantiopure 2-acyl aziridines and their derivatives in good
quantities.
The absolute configuration of (aR,bS)-4a was determined
by comparing its optical rotation and also its retention time
on the HPLC using a chiral column with those of the
authentic sample [(aR,bS)-4a, 99% ee] prepared from the
corresponding epoxy ketone [(aS,bR)-2, 99% ee], which
was obtained by the enantioselective epoxidation of 1a
Scheme 4.

X. L. Jin et al. / Tetrahedron 58 (2002) 8321–8329
8325
4. Experimental
4.1. General methods
4.3. Chiral lanthanide complex-catalyzed Michael
addition of O-alkylhdroxylamines
4.3.1. Asymmetric reacton of chalcone (1a) with
O-methylhydroxylamine (3) catalyzed by Sc(OTf)3-
BINOL-i-Pr2NEt complex (A-Sc). To a mixture of
Sc(OTf)3 (4.9 mg, 0.01 mmol) and (R)-1,10-bi-2-naphthol
(2.9 mg, 0.01 ml) in dry THF (0.5 ml) was added N,N-
diisopropylethylamine (2.6 mg, 0.02 mmol) under Ar, and
the solution was stirred at room temperature for 1 h. After
addition of chalcone (31.5 mg, 0.11 mmol) and 0.2 M
O-methylhydroxylamine in THF (0.55 ml, 0.11 mmol), the
resulting solution was stirred for 18 h at room temperature,
and passed through a short column of silica gel. The eluent
was evaporated and the residue was purified by preparative
TLC (AcOEt–hexana 1:4) to give 3-methoxyamino-1,3-
diphenylpropan-1-one 7a (18.9 mg, 74%) as a colorless
crystal.
Melting points were measured with a Yanako MP-500D
micro melting point apparatus and are uncorrected. IR
1
spectra were taken with JASCO FT/IR-420. H and 13C
NMR spectra were measured on JEOL JNM-EX 400 at
400 MHz and at 100 MHz, respectively. Chemical shifts are
given by d relative to that of internal tetramethylsilane in
CDCl3. FAB mass spectra were obtained with JEOL JMS-
HX110A. Enantiomeric excesses were determined by
high performance liquid chromatography (HPLC) with
Shimadzu LC-9A or LC-10ATVP using B0.46 cm£25 cm
chiral column (Daicel CHIRALCEL OD, CHIRALCEL
OB-H or CHIRALPAK AD). The spectra were detected
with a Simadzu SPD-6A or SPD-10AV UV-VIS detector
and analyzed on Shimadzu C-R6A. Optical rotations were
measured on a Horiba SEPA-300 polarimeter. Elemental
analyses were accomplished at Center of Elementary
Analysis, Faculty of Science, Kyushu University. TLC
was performed on a silica gel plate (Merck, Kieselgel 60
F254, 20 cm£20 cm£0.25 mm). Column chromatography
was carried out with silica gel as an absorbent (Merck,
Kieselgel 60, 70–230 mesh). THF was dried over sodium
metal-9-fluorenone.24 Other solvents were dried over
calcium hydride.
4.3.2. Typical procedure of the RE[(R)-BNP]3-catalyzed
Michael addition: synthesis of (3S)-1,3-diphenyl-3-
diphenylmethoxyaminopropan-1-one (9a). To a suspen-
sion of Sc[(R)-BNP]3·3H2O (10.9 mg, 0.01 mmol) in dry
toluene (1 ml) were successively added 1a (20.8 mg,
0.1 mmol) and 6 (31.9 mg, 0.16 mmol) under Ar, and the
mixture was stirred for 24 h at room temperature. The
reaction mixture was passed through a short column of silica
gel. The eluent was evaporated and the residue was purified
by column chromatography on silica gel (hexane–AcOEt
4:1) to give 9a (40.4 mg, 99%) as colorless needles. Mp
79.5–79.78C. Rf 0.42 (AcOEt–hexane 1:4). [a]2D6¼223.3
(c 1.00, CHCl3, 99.8% ee by the HPLC analysis). HPLC
(CHIRALPAK AD, 2-propanol–hexane 1:19, 0.5 ml/min):
tR 23.9 min for the major enantiomer (30.5 min for the
minor one). IR (KBr): 3062, 3030, 2899, 1671, 1596, 1493,
1450, 1349, 1280, 1207, 1182, 1079, 1006, 985, 921, 847,
4.2. Preparation of catalyst
4.2.1. Typical procedure of the preparation of chiral rare
earth phosphate: scandium(R)-1,10-binaphthyl-2,20-diyl
phosphate, Sc[(R)-BNP]3 (B-Sc). To a refluxing solution of
(R)-1,10-binaphthyl-2,20-diyl hydrogen phosphate (358 mg,
1.03 mmol) and 3N aqueous sodium hydroxide (0.333 ml,
0.999 mmol) in methanol (7 ml) was slowly added a
solution of scandium chloride hexahydrate (84.4 mg,
0.326 mmol) in methanol–water, and the resulting mixture
was stirred for 12 h under same conditions. After cooling the
suspension to room temperature, the precipitate was filtered
and wash with methanol. The colorless solid was dried at
1208C for 15 h in vacuo to give Sc[(R)-BNP]3·3H2O
(325 mg, 87%). IR (KBr): 3060, 1621, 1592, 1509, 1466,
1328, 1237, 1210, 1155, 1109, 1071, 993, 968, 949, 888,
871, 816, 750, 722, 659, 568 cm21. [a]D25¼2492.2 (c 1.06,
THF). Anal. calcd for C60H36O12P3Sc·3H2O: C, 63.17; 3.71.
Found: C, 63.27; H, 3.55. This catalyst was dried again for
5 min by heat-gun under vacuum just before use.
1
747, 705, 657, 599, 411 cm21. H NMR (CDCl3, d): 3.30
(1H, dd, J¼4.9, 17.3 Hz), 3.50 (1H, dd, J¼8.1, 17.3 Hz),
4.78 (1H, dd, J¼4.9, 8.1 Hz), 5.53 (1H, s), 6.18 (1H, s),
6.95–6.98 (2H, m), 7.15–7.53 (16H, m), 7.85–7.87 (2H,
m). 13C NMR (CDCl3, d): 42.68, 61.22, 86.93, 127.21,
127.43, 127.48, 127.70, 127.91, 128.06, 128.12, 128.34,
128.45, 128.53, 141.25, 141.30, 198.32. Anal. calcd for
C28H25NO2: C, 82.53; H, 6.18; N, 3.44. Found: C, 82.56; H,
6.16; N, 3.43.
4.3.3. (3S)-1,3-Diphenyl-3-methoxyaminopropan-1-one
(7a). Rf 0.30 (AcOEt–hexane 1:4). [a]2D2¼29.5 (c 1.00,
CHCl3, 50% ee by the HPLC analysis). HPLC
(CHIRALPAK OD, 2-propanol–hexane 1:50, 0.5 ml/min):
tR 17.5 min for the major enantiomer (23.8 min for the
4.2.2. Lanthanum (R)-1,10-binaphthyl-2,20-diyl phos-
phate, La[(R)-BNP]3 (B-La). Colorless solid. IR (KBr):
3060, 1620, 1592, 1508, 1466, 1392, 1238, 1215, 1103,
1071, 992, 965, 945, 867, 841, 817, 750, 720, 659, 595, 582,
568, 538, 495 cm21. [a]D25¼2356.0 (c 1.00, THF). Anal.
calcd for C60H36O12P3La·H2O: C, 60.12; 3.20. Found: C,
59.72; H, 3.30.
1
minor one). H NMR (CDCl3, d): 3.28 (1H, dd, J¼4.9,
17.1 Hz), 3.40 (3H, s), 3.49 (1H, dd, J¼8.3, 17.2 Hz), 4.69
(1H, dd, J¼5.0, 8.2 Hz), 6.20 (1H, s), 7.26–7.53 (8H, m),
7.90 (2H, t). 13C NMR (CDCl3, d): 42.44, 60.80, 61.97,
127.38, 127.46, 127.84, 128.26, 128.37, 133.00, 136.56,
140.90, 198.07. CAS registry no. 52322-76-6 (rac).
4.2.3. Ytterbium (R)-1,10-binaphthyl-2,20-diyl phosphate,
Yb[(R)-BNP]3 (B-Yb). Colorless solid. IR (KBr): 3616,
3065, 1621, 1592, 1509, 1466, 1329, 1238, 1215, 1112,
1071, 967, 945, 870, 817, 750, 568 cm21. [a]D25¼2395.0 (c
1.00, THF). Anal. calcd for C60H36O12P3Yb·H2O: C, 58.45;
3.11. Found: C, 58.17; H, 3.11.
4.3.4. 3-Benzyloxyamino-1,3-diphenylpropan-1-one (8a).
Colorless solid. Mp 80.9–81.18C. Rf 0.52 (AcOEt–hexane
1:4). HPLC (CHIRALPAK AD, ethanol–hexane 1:19,
0.5 ml/min): tR 39.3 min for the major enantiomer
(35.4 min for the minor one). IR (KBr): 3282, 3026, 2908,

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X. L. Jin et al. / Tetrahedron 58 (2002) 8321–8329
1671, 1596, 1496, 1449, 1409, 1369, 1276, 1230, 1131,
1
141.19, 197.96. Anal. calcd for C28H24ClNO2: C, 76.09; H,
5.47; N, 3.17. Found: C, 76.10; H, 5.48; N, 3.15.
1067, 1003, 984, 759, 742, 701, 605, 583 cm21. H NMR
(CDCl3, d): 3.29 (1H, dd, J¼4.9, 17.1 Hz), 3.49 (1H, dd,
J¼7.8, 17.1 Hz), 4.52 and 4.56 (2H, each d, J¼11.7 Hz),
4.71 (1H, d, J¼4.9, 7.8 Hz), 6.18 (1H, s), 7.18–7.45 (12H,
m), 7.54 (1H, t, J¼7.3 Hz), 7.89 (2H, d, J¼7.3 Hz). 13C
NMR (CDCl3, d): 42.65, 61.14, 127.71, 127.76, 128.06,
128.26, 128.46, 128.55, 133.19, 136.74, 137.60, 141.02,
198.30. Anal. calcd for C22H21NO2: C, 79.67; H, 6.40; N,
4.20. Found: C, 79.73; H, 6.39; N, 4.23.
4.3.8. 3-(3-Chlorophenyl)-3-diphenylmethoxyamino-1-
phenylpropan-1-one (9e). Colorless needles. Mp 93.6–
93.88C. Rf 0.46 (AcOEt–hexana 1:4). [a]1D9¼224.9 (c 1.00,
CHCl3, 99.8% ee by the HPLC analisis). HPLC
(CHIRALPAK AD, 2-propanol–hexane 1:19, 0.5 ml/min):
tR 20.8 min for the major enantiomer (25.4 min for the
minor one). IR (KBr): 3263, 3063, 3029, 2902, 1675, 1597,
1449, 1424, 1359, 1299, 1273, 1204, 1070, 1003, 791, 748,
1
4.3.5. 3-Diphenylmethoxyamino-3-(4-methylphenyl)-1-
phenyl-propan-1-one (9b). Colorless solid. Mp 93.7–
93.98C. Rf 0.44 (AcOEt–hexana 1:4). [a]2D6¼221.4 (c
1.00, CHCl3, 99.7% ee by the HPLC analysis). HPLC
(CHIRALPAK AD, 2-propanol–hexane 1:19, 0.5 ml/min):
tR 24.0 min for the major enantiomer (35.3 min for the
minor one). IR (KBr): 3255, 3062, 3029, 2888, 1960, 1678,
1597, 1582, 1511, 1496, 1449, 1402, 1360, 1343, 1277,
701, 686, 606 cm21. H NMR (CDCl3, d): 3.26 (1H, dd,
J¼4.6, 17.6 Hz), 3.46 (1H, dd, J¼8.3, 17.6 Hz), 4.74 (1H,
dd, J¼4.6, 8.3 Hz), 5.52 (1H, s), 6.21 (1H, s), 6.98–7.01
(2H, m), 7.19–7.35 (11H, m), 7.41 (2H, t, J¼7.8 Hz), 7.47
(1H, s), 7.54 (1H, t, J¼7.3 Hz), 7.85–7.87 (2H, m). 13C
NMR (CDCl3, d): 42.28, 60.63, 87.07, 126.19, 127.21,
127.41, 127.53, 127.82, 128.04, 128.19, 128.40, 128.60,
129.70, 133.38, 134.27, 136.49, 140.91, 141.12, 143.53,
197.88. Anal. calcd for C28H24ClNO2: C, 76.09; H, 5.47; N,
3.17. Found: C, 76.07; H, 5.50; N, 3.15.
1204, 1008, 984, 814, 752, 700, 419 cm21 1H NMR
.
(CDCl3, d): 2.34 (3H, s), 3.28 (1H, dd, J¼5.1, 17.3 Hz),
3.51 (1H, dd, J¼7.9, 17.3 Hz), 4.74 (1H, dd, J¼5.1, 7.9 Hz),
5.55 (1H, s), 6.10 (1H, s), 7.01–7.03 (2H, m), 7.14–7.40
(14H, m), 7.51 (1H, t, J¼7.1 Hz), 7.85 (2H, d, J¼7.1 Hz).
13C NMR (CDCl3, d): 21.13, 42.76, 60.98, 86.89, 127.23,
127.41 127.46, 127.79, 128.06, 128.13, 128.31, 128.50,
129.11, 133.12, 136.76, 137.33, 138.09, 141.21, 141.36,
198.40. Anal. calcd for C29H27NO2: C, 82.63; H, 6.46; N,
3.32. Found: C, 82.61; H, 6.47; N, 3.32.
4.3.9. 3-Diphenylmethoxyamino-3-(4-fluorophenyl)-1-
phenylpropan-1-one (9f). Colorless solid. Mp 115.4–
115.68C. Rf 0.44 (AcOEt–hexana 1:4). [a]2D5¼224.0 (c
1.00, CHCl3, 99.4% ee by the HPLC analisis). HPLC
(CHIRALPAK AD, 2-propanol–hexane 1:19, 0.5 ml/min):
tR 25.7 min for the major enantiomer (34.6 min for the
minor one). IR (KBr): 3267, 3062, 3030, 2905, 2889, 1677,
1601, 1506, 1450, 1353, 1271, 1204, 1152, 1082, 1003, 980,
1
4.3.6. 3-Diphenylmethoxyamino-3-(4-methoxyphenyl)-1-
phenylpropan-1-one (9c). Colorless solid. Mp 105.7–
105.88C. Rf 0.32 (AcOEt–hexane 1:4). [a]2D0¼224.7 (c
1.00, CHCl3, .99.8% ee by the HPLC analysis). HPLC
(CHIRALPAK AD, 2-propanol–hexane 1:19, 0.5 ml/min):
tR 38.4 min for the major enantiomer (52.1 min for the
minor one). IR (KBr): 3060, 3030, 2887, 1678, 1512, 1452,
842, 752, 701, 687, 546 cm21. H NMR (CDCl3, d): 3.26
(1H, dd, J¼5.1, 17.3 Hz), 3.47 (1H, dd, J¼7.8, 17.3 Hz),
4.76 (1H, dd, J¼5.1, 7.8 Hz), 5.51 (1H, s), 6.15 (1H, s),
7.00–7.05 (2H, m), 7.19–7.34 (8H, m), 7.39–7.43 (4H, m),
7.54 (1H, dt, J¼0.7, 7.6 Hz), 7.86 (2H, d, J¼7.6 Hz). 13C
NMR (CDCl3, d): 42.59, 60.45, 87.03, 115.13, 115.34,
127.17, 127.40, 127.50, 128.04, 128.18, 128.38, 128.58,
129.44, 129.52, 133.30, 136.60, 137.01, 137.04, 141.02,
141.23, 161.04, 163.48, 198.11. Anal. calcd for C28H24FNO2:
C, 79.04; H, 5.67; N, 3.29. Found: C, 79.05; H, 5.73; N, 3.29.
1
1244, 1207, 1176, 1028, 835, 752, 702 cm21. H NMR
(CDCl3, d): 3.28 (1H, dd, J¼5.4, 17.1 Hz), 3.51 (1H, dd,
J¼7.8, 17.1 Hz), 3.81 (3H, s), 4.73 (1H, dd, J¼5.4, 7.8 Hz),
5.53 (1H, s), 6.08 (1H, s), 6.87 (2H, d, J¼8.5 Hz), 7.03–
7.04 (1H, m), 7.18–7.42 (12H, m), 7.52 (1H, t, J¼7.3 Hz),
7.86 (2H, d, J¼7.3 Hz). 13C NMR (CDCl3, d): 42.77, 55.29,
60.64, 86.93, 113.80, 127.22, 127.43, 127.45, 128.07,
128.16, 128.32, 128.52, 129.02, 133.14, 136.78, 141.22,
141.37, 159.13, 198.45. Anal. calcd for C29H27NO3: C,
79.61; H, 6.22; N, 3.20. Found: C, 79.50; H, 6.22; N, 3.25.
4.3.10. 3-Diphenylmethoxyamino-1-phenyl-3-(4-cyano-
phenyl)propan-1-one (9g). Colorless solid. Mp 139.0–
139.28C. Rf 0.36 (AcOEt–hexana 1:4). [a]1D9¼234.5 (c
1.00, CHCl3, .99.8% ee by the HPLC analysis). HPLC
(CHIRALPAK AD, 2-propanol–hexane 1:19, 1.0 ml/min):
tR 47.1 min for the major enantiomer (57.8 min for the
minor one). IR (KBr): 3259, 3064, 3030, 2890, 2232, 1678,
1450, 1359, 1276, 1207, 1002, 984, 839, 764, 750, 703, 685,
562, 403 cm21. 1H NMR (CDCl3, d): 3.26 (1H, dd, J¼5.0,
17.8 Hz), 3.43 (1H, dd, J¼8.1, 17.8 Hz), 4.82 (1H, br s),
5.51 (1H, s), 6.25 (1H, s), 6.96–6.98 (2H, m), 7.19–7.20
(3H, m), 7.24–7.34 (5H, m), 7.41 (2H, t, J¼7.6 Hz), 7.53–
7.63 (5H, m), 7.84–7.86 (2H, m). 13C NMR (CDCl3, d):
41.98, 60.62, 87.07, 111.34, 118.78, 127.06, 127.26, 127.44,
127.58, 127.97, 128.18, 128.42, 128.59, 128.63, 132.20,
133.54 136.23, 140.71, 140.94, 147.03, 197.40. Anal. calcd
for C29H24N2O2: C, 80.53; H, 5.59; N, 6.48. Found: C,
80.49; H, 5.63; N, 6.46.
4.3.7. 3-(4-Chlorophenyl)-3-diphenylmethoxyamino-1-
phenylpropan-1-one (9d). Colorless needles. Mp 135.5–
135.78C. Rf 0.44 (AcOEt–hexane 1:4). [a]2D6¼222.1 (c
1.00, CHCl3, 99.7% ee by the HPLC analysis). HPLC
(CHIRALPAK AD, 2-propanol–hexane 1:19, 0.5 ml/min):
tR 27.5 min for the major enantiomer (40.1 min for the
minor one). IR (KBr): 3264, 3063, 3025, 2905, 2873, 2360,
1680, 1490, 1450, 1356, 1270, 1202, 1090, 1003, 816, 750,
1
701, 688, 542, 418 cm21. H NMR (CDCl3, d): 3.18 (1H,
dd, J¼5.1, 17.6 Hz), 3.38 (1H, dd, J¼7.9, 17.6 Hz), 4.67 (1H,
dd, J¼5.1, 7.9 Hz), 5.44 (1H, s), 6.09 (1H, s), 6.91–6.94 (2H,
m), 7.11–7.26 (10H, m), 7.30–7.35 (4H, m), 7.46 (1H, t,
J¼7.3 Hz), 7.77–7.79 (2H, m). 13C NMR (CDCl3, d): 42.40,
60.47, 87.03, 127.16, 127.39, 127.51, 128.02, 128.18, 128.38,
128.56, 128.59, 129.26, 133.34, 136.53, 139.87, 140.97,
4.3.11. 3-Diphenylmethoxyamino-3-(4-nitrophenyl)-1-
phenylpropan-1-one (9h). Yellow needles. Mp
138.1–138.38C.
Rf
0.29
(AcOEt–hexane
1:4).

X. L. Jin et al. / Tetrahedron 58 (2002) 8321–8329
8327
[a]2D5¼232.5 (c 1.00, CHCl3, .99.8% ee by the HPLC
analysis). HPLC (CHIRALPAK AD, 2-propanol–hexane
1:9, 0.5 ml/min): tR 46.1 min for the major enantiomer
(60.9 min for the minor one). IR (KBr): 3260, 3062, 3030,
2902, 2880, 1682, 1598, 1515, 1450, 1274, 1205, 1002, 980,
1:4). [a]1D9¼þ311.7 (c 1.00, CHCl3, 99.7% ee by the HPLC
analysis). HPLC (CHIRALCEL OD, 2-propanol–hexane
1:19, 0.5 ml/min): tR 16.6 min for the major enantiomer
(23.5 min for the minor one). IR (KBr): 3216, 1657, 1450,
1398, 1266, 1234, 1042, 1010, 855, 807, 783, 692,
1
1
754, 701, 688, 626, 540 cm21. H NMR (CDCl3, d): 3.28
529 cm21. H NMR (CDCl3, d): 2.36 (3H, s), 2.65 (1H, br
(1H, dd, J¼5.0, 17.6 Hz), 3.46 (1H, dd, J¼8.1, 17.6 Hz),
4.87 (1H, dd, J¼5.0, 8.1 Hz), 5.53 (1H, s), 6.27 (1H, s),
6.98–6.99 (2H, m), 7.18–7.34 (8H, m), 7.43 (2H, t,
J¼7.8 Hz), 7.56 (1H, dt, J¼1.2, 8.1 Hz), 7.62 (2H, d,
J¼8.1 Hz), 7.86 (2H, d, J¼8.5 Hz), 8.19 (2H, d, J¼7.8 Hz).
13C NMR (CDCl3, d): 42.05, 60.43, 87.14, 123.64, 127.11,
127.29, 127.64, 127.67, 128.02, 128.23, 128.48, 128.70,
133.63, 136.25, 140.74, 140.96, 147.39, 149.14, 197.33.
Anal. calcd for C28H24N2O4: C, 74.32; H, 5.35; N, 6.19.
Found: C, 74.44; H, 5.41; N, 6.18.
s), 3.15 (1H, br s), 3.48 (1H, br s), 7.17 (2H, d, J¼8.1 Hz),
7.26 (2H, d, J¼8.1 Hz), 7.45–7.50 (2H, m), 7.58–7.63 (1H,
m), 7.98–8.00 (2H, m). 13C NMR (CDCl3, d): 21.16, 43.50,
44.18, 126.07, 128.78, 129.23, 133.75, 135.35, 135.94,
137.66, 195.77. Anal. calcd for C16H15NO: C, 80.98; H,
6.37; N, 5.90. Found: C, 80.94; H, 6.38; N, 5.94. CAS
registry no. 101854-88-0 (2R,3S).
4.4.3. trans-2-Benzoyl-3-(4-methoxylphenyl)aziridine
(4c). An orange oil. Rf 0.22 (AcOEt–hexane 1:4).
[a]2D0¼þ334.2 (c 1.00, CHCl3, .99.8% ee by the HPLC
analysis). HPLC (CHIRALCEL OD, 2-propanol–hexane
1:19, 0.5 ml/min): tR 28.1 min for the major enantiomer
(43.5 min for the minor one). IR (KBr): 3264, 2836, 1666,
1612, 1516, 1450, 1403, 1303, 1252, 1177, 1033, 814,
693 cm21. 1H NMR (CDCl3, d): 2.65 (1H, br s), 3.14 (1H, br
d, J¼2.2 Hz), 3.48 (1H, br d, J¼2.4 Hz), 3.81 (3H, s), 6.88–
6.90 (2H, m), 7.28–7.30 (2H, m), 7.46–7.50 (2H, m), 7.58–
7.62 (1H, m), 7.98–8.00 (2H, m). 13C NMR (CDCl3, d):
43.34, 44.11, 55.29, 113.97, 127.29, 128.27, 128.77, 130.34,
133.74, 135.93, 159.39, 195.72. HRMS-FAB (m/z): [MþH]
calcd for C16H16NO2, 254.1181; found, 254.1211.
4.3.12. 3-Diphenylmethoxyamino-4-methyl-1-phenyl-
pentan-1-one (9i). An oil. Rf 0.46 (AcOEt–hexane 1:4).
[a]2D3¼238.4 (c 1.58, CHCl3, 97.8% ee by the HPLC
analysis). HPLC (CHIRALPAK AD, ethanol–hexane
1:300, 0.5 ml/min): tR 25.1 min for the major enantiomer
(20.7 min for the minor one). IR (KBr): 2959, 2360, 1734,
1717, 1684, 1653, 1558, 1541, 1521, 1507, 1456, 745, 696,
668, 484, 468, 458 cm21. 1H NMR (CDCl3, d): 0.94 (3H, d,
J¼6.8 Hz), 0.98 (3H, d, J¼6.8 Hz), 2.03–2.11 (1H, m),
2.99 (1H, dd, J¼4.2, 16.6 Hz), 3.20 (1H, dd, J¼8.3,
16.6 Hz), 3.36–3.41 (1H, m), 5.63 (1H, s), 5.88 (1H, s),
7.21–7.29 (10H, m), 7.42 (2H, t, J¼7.8 Hz), 7.54 (1H, t,
J¼7.3 Hz), 7.91 (2H, d, J¼7.3 Hz). 13C NMR (CDCl3, d):
18.56, 19.39, 29.20, 37.40, 62.31, 86.52, 127.02, 127.16,
127.30, 127.36, 128.08, 128.23, 128.45, 132.91, 137.20,
141.61, 141.71, 199.92. HRMS-FAB (m/z): [MþH] calcd
for C25H28NO2, 374.2120; found, 374.2125.
4.4.4. trans-2-Benzoyl-3-(4-chlorophenyl)aziridine (4d).
Yellow needles. Mp 97.2–97.48C. Rf 0.37 (AcOEt–hexane
1:4). [a]1D9¼þ291.9 (c 1.00, CHCl3, 99.7% ee by the HPLC
analysis). HPLC (CHIRALCEL OD, 2-propanol–hexane
1:4, 0.5 ml/min): tR 12.7 min for the major enantiomer
(20.4 min for the minor one). IR (KBr): 3278, 1659, 1450,
1394, 1259, 1234, 1008, 812, 705 cm21. 1H NMR (CDCl3,
d): 2.68 (1H, br t), 3.15 (1H, br d, J¼6.8 Hz), 3.45 (1H, br d,
J¼5.6 Hz), 7.29–7.35 (4H, m), 7.50 (2H, t, J¼7.3 Hz), 7.63
(1H, t, J¼7.3 Hz), 7.97–8.00 (2H, m). 13C NMR (CDCl3,
d): 42.76, 44.06, 126.51, 127.53, 128.29, 128.46, 128.72,
128.86, 133.66, 133.94, 135.77, 136.87, 195.37. Anal. calcd
for C15H12ClNO: C, 69.91; H, 4.69; N, 5.43. Found: C,
70.08; H, 4.67; N, 5.51. CAS registry no. 10854-87-9
(2R,3S).
4.4. Base-catalyzed aziridine ring formation
4.4.1. Synthesis of (2S,3R)-2-Benzoyl-3-phenylaziridine
(4a). To a solution of 9a (20.35 mg, 0.05 mmol) in dry THF
(0.5 ml) was added NaO-t-Bu (0.1 M in THF, 50 ml,
0.005 mmol) under Ar and the mixture was stirred for
1.5 h at room temperature. The reaction mixture was passed
through a short column of silica gel, the eluent was
evaporated, and the residue was purified by chromatography
on silica gel (AcOEt–hexane 1:8) to give (2S,3R)-4a
(11.2 mg, 100%) as a colorless solid. Mp 124.6–124.88C.
Rf 0.34 (AcOEt–hexane 1:4). [a]1D9¼þ268.7 (c 1.00,
CHCl3, 99.8% ee by the HPLC analysis). HPLC
(CHIRALCEL OD, 2-propanol–hexane 1:19, 0.5 ml/min):
tR 21.4 min for the major enantiomer (27.8 min for the
minor one). IR (KBr): 3222, 1660, 1449, 1413, 1264, 1032,
4.4.5. trans-2-Benzoyl-3-(3-chlorophenyl)aziridine (4e).
An oil. Rf 0.52 (AcOEt–hexane 1:4). [a]1D9¼þ277.8 (c 1.04,
CHCl3, 99.8% ee by the HPLC analysis). HPLC
(CHIRALCEL OD, 2-propanol–hexane 1:19, 0.5 ml/min):
tR 19.2 min for the major enantiomer (43.6 min for the
minor one). IR (KBr): 3266, 1667, 1599, 1578, 1449, 1408,
1
1
1011, 844, 756, 698, 594, 529 cm21. H NMR (CDCl3, d):
1259, 1228, 1010, 773, 712, 688 cm21. H NMR (CDCl3,
2.67 (1H, br t), 3.18 (1H, br d, J¼7.1 Hz), 3.51 (1H, br d,
J¼5.6 Hz), 7.29–7.39 (5H, m), 7.47–7.51 (2H, m), 7.60–
7.63 (1H, m), 7.99–8.01 (2H, m). 13C NMR (CDCl3, d):
43.51, 44.07, 126.18, 127.86, 128.30, 128.53, 128.79,
133.79, 135.89, 138.30, 195.68. Anal. calcd for
C15H13NO: C, 80.69; H, 5.87; N, 6.27. Found: C, 80.49;
H, 5.90; N, 6.22. CAS registry no. 74280-88-9 (2S,3R),
7570-84-5 (2R,3S), 65309-87-7 (2R,3S).
d): 2.68 (1H, br t, J¼8.5 Hz), 3.14 (1H, dd, J¼2.2, 9.3 Hz),
3.48 (1H, dd, J¼2.2, 8.1 Hz), 7.24–7.28 (3H, m), 7.36 (1H,
s), 7.47–7.51 (2H, m), 7.59–7.64 (1H, m), 7.97–8.00 (2H,
m). 13C NMR (CDCl3, d): 42.63, 43.90, 124.55, 126.15,
127.99, 128.29, 128.82, 129.75, 133.93, 134.57, 135.68,
140.45, 195.26. Anal. calcd for C15H12ClNO: C, 69.91; H,
4.69; N, 5.43. Found: C, 69.87; H, 4.73; N, 5.40.
4.4.6. trans-2-Benzoyl-3-(4-fluorophenyl)aziridine (4f).
Yellow solid. Mp 71.8–72.08C. Rf 0.34 (AcOEt–hexana
1:4). [a]1D9¼þ234.6 (c 1.00, CHCl3, 99.4% ee by the HPLC
4.4.2. trans-2-Benzoyl-3-(4-methylphenyl)aziridine (4b).
Yellow solid. Mp 88.8–90.08C. Rf 0.37 (AcOEt–hexane

8328
X. L. Jin et al. / Tetrahedron 58 (2002) 8321–8329
analysis). HPLC (CHIRALCEL OD, 2-propanol–hexane
1:4, 0.5 ml/min): tR 12.9 min for the major enantiomer
(23.9 min for the minor one). IR (KBr): 3260, 1659, 1598,
propan-1-one 39b,c (280 mg, 1.2 mmol) in water–methanol
(1:6, 7 ml) was added methyl formate (1 ml) and sodium
azide (350 mg, 5.4 mmol), and the resulting solution was
stirred for 5 h at 608C and passed through a short column of
anhydrous MgSO4 on silica gel. The eluent was evaporated,
and the residue was subjected to column chromatography on
silica gel (AcOEt–hexane 1:30) to give the desired (2S,3S)-
10 (131 mg, 39%) as a colorless crystal. Mp 86.1–86.98C.
Rf 0.31 (AcOEt–hexane 1:4). [a]2D5¼þ76.0 (c 1.00,
CHCl3). IR (KBr): 3422, 3057, 3036, 2946, 2569, 2469,
2105, 1969, 1677, 1493, 1450, 1398, 1343, 1273, 1182,
1510, 1449, 1397, 1264, 1215, 1032, 1013, 817, 690 cm21
.
1H NMR (CDCl3, d): 2.67 (1H, br s), 3.16 (1H, br s), 3.46
(1H, br s), 7.01–7.08 (2H, m), 7.32–7.36 (2H, m), 7.5 (2H,
t, J¼8.1 Hz), 7.63 (1H, dt, J¼1.2, 7.8 Hz), 7.99 (2H, dd,
J¼1.0, 8.1 Hz). 13C NMR (CDCl3, d): 42.82, 44.04, 115.38,
115.60, 127.76, 127.84, 128.30, 128.86, 133.90, 134.07,
134.10, 135.87, 161.28, 163.73, 195.52. Anal. calcd for
C15H12FNO: C, 74.67; H, 5.01; N, 5.81. Found: C, 74.31; H,
5.06; N, 5.84. CAS registry no. 101854-86-8 (2R,3S).
1111, 1074, 1031, 990, 848, 694, 611 cm21 1H NMR
.
(CDCl3, d): 3.79 (1H, d, J¼7.3 Hz), 4.81 (1H, d, J¼3.9 Hz),
5.29 (1H, dd, J¼3.9, 7.3 Hz), 6,99–7.01 (2H, m), 7.11–7.18
(3H, m), 7.29–7.38 (2H, m), 7.47 (1H, t, J¼7.3 Hz), 7.63–
7.65 (2H, m). 13C NMR (CDCl3, d): 67.82, 75.57, 127.68,
128.39, 128.52, 128.65, 128.72, 128.77, 130.05, 133.95,
134.11, 134.28, 198.40. Anal. calcd for C15H13N3O2: C,
67.41; H, 4.90; N, 15.72. Found: C, 67.40; H, 4.86; N, 15.79.
HRMS-FAB (m/z): [M] calcd for C15H13N3O2, 268.1086;
found, 268.1078.
4.4.7. trans-2-Benzoyl-3-(4-cyanophenyl)aziridine (4g).
Yellow solid. Mp 113.5–113.78C. Rf 0.18 (AcOEt–hexane
1:4). [a]1D9¼þ326.3 (c 1.00, CHCl3, .99.8% ee by the
HPLC analysis). HPLC (CHIRALCEL OD, 2-propanol–
hexane 1:4, 0.5 ml/min): tR 26.7 min for the major
enantiomer (36.5 min for the minor one). IR (KBr): 3273,
3072, 2224, 1658, 1450, 1261, 1232, 1009, 815, 683 cm21
.
1H NMR (CDCl3, d): 2.74 (1H, br t, J¼8.3 Hz), 3.21 (1H,
dd, J¼2.2, 9.1 Hz), 3.49 (1H, dd, J¼2.2, 8.3 Hz), 7.48–7.53
(4H, m), 7.63–7.67 (3H, m), 7.97–7.99 (2H, m). 13C NMR
(CDCl3, d): 42.50, 44.10, 111.61, 118.67, 126.99, 128.33,
128.94, 132.38, 134.16, 135.60, 143.80, 194.91. Anal. calcd
for C16H12N2O: C, 77.40; H, 4.87; N, 11.28. Found: C,
77.36; H, 4.94; N, 11.22.
4.5.2. (2R,3S)-2-Benzoyl-3-phenylaziridine (4a).
A
mixture of (2S,3S)-10 (18.6 mg, 0.07 mmol) and triphenyl-
phosphine (18.2 mg, 0.07 mmol) in acetonitrile (1 ml) was
stirred at room temperature for 4 h. After evaporation, the
residue was subjected to column chromatography on silica
gel (AcOEt–hexane 1:30) to give the desired (2R,3S)-4a
(10.3 mg, 66%). [a]2D3¼2307.8 (c 1.00, CHCl3).
4.4.8. trans-2-Benzoyl-3-(4-nitrophenyl)aziridine (4h).
An orange solid. Mp 136.8–137.08C. Rf 0.25 (AcOEt–
hexane 1:4). [a]1D9¼þ282.5 (c 1.00, CHCl3, .99.8% ee by
the HPLC analysis). HPLC (CHIRALCEL OD, 2-propa-
nol–hexane 1:4, 0.5 ml/min): tR 27.9 min for the major
enantiomer (39.4 min for the minor one). IR (KBr): 3266,
1667, 1601, 1516, 1449, 1345, 1261, 1232, 1019, 829, 746,
709 cm21. 1H NMR (CDCl3, d): 2.78 (1H, br t, J¼8.5 Hz),
3.26 (1H, dd, J¼2.2, 9.1 Hz), 3.51 (1H, dd, J¼2.2, 8.1 Hz),
7.49–7.56 (4H, m), 7.63–7.67 (1H, m), 7.98–8.00 (2H, m),
8.23 (2H, d, J¼8.5 Hz). 13C NMR (CDCl3, d): 42.28, 44.16,
123.85, 127.09, 128.35, 128.97, 134.21, 135.58, 145.80,
147.60, 194.83. Anal. calcd for C15H12N2O3: C, 67.16; H,
4.51; N, 10.44. Found: C, 67.20; H, 4.56; N, 10.42. CAS
registry No. 76336-95-3 (2R,3S), 51659-22-4 (rac).
Acknowledgements
This work was supported by a Grant-in-Aid for Scientific
Research on Priority Areas from the Ministry of Education,
Culture, Sports, Science and Technology, Japan, the Japan
Society for the Promotion of Science, and also by the
Kyushu University P&P Programs ‘Green Chemistry’ (to
J. I.).
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