The mechanism of [2 + 1] and [2 + 2] cycloaddition reactions of 1-phenylseleno-2-(trimethylsilyl)ethene: An isotopic labelling study

Article abstract of DOI:10.1039/a909919k

The reactions of deuterio-labelled 1-seleno-2-sitylethenes with trimethyl 2-phosphonoacrylate 2 and methyl vinyl ketone 4 in the presence of SnCl₄ gave deuterio-substituted cyclopropanes with 1,2-silicon migration. The reaction of deuterio-labe

Full text of DOI:10.1039/a909919k

View Article Online / Journal Homepage / Table of Contents for this issue
The mechanism of [2 ؉ 1] and [2 ؉ 2] cycloaddition reactions
of 1-phenylseleno-2-(trimethylsilyl)ethene: an isotopic labelling
study†
1
Shoko Yamazaki,*a Yuichiro Yanasea and Kagetoshi Yamamotob
a Department of Chemistry, Nara University of Education, Takabatake-cho, Nara 630-8528,
Japan
b Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka,
Osaka 560-0043, Japan
Received (in Cambridge, UK) 21st December 1999, Accepted 5th April 2000
Published on the Web 25th May 2000
The reactions of deuterio-labelled 1-seleno-2-silylethenes with trimethyl 2-phosphonoacrylate 2 and methyl vinyl
ketone 4 in the presence of SnCl4 gave deuterio-substituted cyclopropanes with 1,2-silicon migration. The reaction
of deuterio-labelled 1-seleno-2-silylethenes with dimethyl 2,2-dicyanoethene-1,1-dicarboxylate 6 in the presence of
SnCl4 and ZnBr2 gave deuterium-substituted cyclobutanes without silicon migration. This labelling study strongly
confirms the 1,2-silicon migration for [2 ϩ 1] cycloadditions of 1 and non-1,2-silicon migration for the [2 ϩ 2]
cycloaddition reactions, respectively.
migration in the resulting zwitterionic intermediate. In order to
Introduction
clarify the origin of preferential formation of a cyclopropane
instead of a cyclobutane, various theoretical studies have been
carried out.1a,c–f Recently, higher level calculations have been
initiated which promise to unveil the detailed features of this
novel cyclopropanation.2 The theoretical study indicates that
silicon migration occurs, rather than selenium migration.
Because the possibility of selenium migration instead of silicon
migration (Scheme 2) also exists,3 we wished to make sure
We have recently reported a novel [2 ϩ 1] cycloaddition method
involving reactions of the (E)-1-phenylseleno-2-silylethene
1 with electrophilic olefins to afford cyclopropane products
with high stereoselectivity in the presence of Lewis acids
(Scheme 1).1 This new approach to cyclopropane construction
is based on a 1,2-silicon-migration process. A possible reaction
mechanism for the [2 ϩ 1] cycloaddition involves a 1,2-silicon
Scheme 2 Alternative mechanism for [2 ϩ 1] cycloaddition of 1. The
carbon numbering of 1 and 2 corresponds to Scheme 1.
experimentally that this mechanism involves not selenium but
silicon migration.
In addition to 2 and 4, (E)-1-phenylseleno-2-silylethenes
such as 1 react with some electrophilic olefins such as dimethyl
2,2-dicyanoethene-1,1-dicarboxylate 64 to afford cyclobutane
products without 1,2-silicon migration (Scheme 3).5 The
dependency of the regiochemistry on Lewis acids for cyclo-
butane formation with 1 has also been observed. In the ZnBr2
case, the involvement of both silicon migration and selenium
migration as an alternative mechanism cannot be completely
ruled out (Scheme 4).
Scheme 1 A possible reaction mechanism for [2 ϩ 1] cycloaddition of
1 with electrophilic olefins. The carbon numbering refers to starting
olefins 1 and 2. a 1,2-Si shift and C3-C2 ring closure could be stepwise
rather than concerted.
In order to gain more insight into the mechanism of these
transformations, reactions using one-deuterium-labelled 1-
seleno-2-silylethenes 1-1-d or 1-2-d are required. The labelled
nucleophilic olefins 1-1-d and 1-2-d were readily prepared
† NOESY spectra for 3-1-d and 9-2-d and HMBC spectra for 7-1-d and
8-1-d are available as supplementary data. For direct electronic access
see http://www.rsc.org/suppdata/p1/a9/a909919k/
DOI: 10.1039/a909919k
J. Chem. Soc., Perkin Trans. 1, 2000, 1991–1996
This journal is © The Royal Society of Chemistry 2000
1991

View Article Online
Results and discussion
The deuterium-labelled selenosilylethenes 1-1-d and 1-2-d were
prepared by treatment of the corresponding (E)-1- and -2-
deuterio-1-tributylstannyl-2-(trimethylsilyl)ethenes with n-
butyllithium followed by diphenyl diselenide, according to
the preparation method of non-labelled substrate 1 [equations
(1) and (2)].1a The precursors, (E)-1- and -2-deuterio-1-tributyl-
(1)
(2)
stannyl-2-(trimethylsilyl)ethenes 11-1-d and 11-2-d were
obtained by the reaction of (deuterioethynyl)trimethyl-
silane6 10-d and tri-n-butyltin hydride, and the reaction of
(ethynyl)trimethylsilane 10 and tri-n-butyltin deuteride,7
respectively.
There are various electrophilic olefins that give cycloprop-
anes in their reaction with 1-seleno-2-silylethenes. Amongst
them, the reaction of trimethyl 2-phosphonoacrylate 2 with
deuterium-labelled 1 was examined first because it affords
cyclopropanes chemoselectively, stereoselectively and in high
yield. The reaction of 1-deuterio-1-phenylseleno-2-(trimethyl-
silyl)ethene 1-1-d with phosphonoacrylate 2 in the presence of
SnCl4 at Ϫ78 ЊC gave a C-1 deuterio-substituted cyclopropane
product 3-1-d in 76% yield [equation (3)].‡ Similarly, reaction
Scheme 3 A possible mechanism for [2 ϩ 2] cycloaddition of 1 and 6
in the presence of SnCl4 or ZnBr2. The carbon numbering refers to
starting olefins 1 and 6.
‡ The chemical shifts of our deuterium-labelled cyclopropanes and
cyclobutanes are essentially the same as for the non-deuterium-labelled
products which were reported previously, except at the deuterium-
labelled positions.1,5 Therefore, the stereochemistry of these cyclo-
adducts is assigned as the same as the non-deuterium products reported
previously. An example of the determination of the stereochemistry
for the deuterium-labelled cyclopropane 3-1-d by NMR is as follows. In
3-1-d, NOEs [between SiMe3 and H-4 (cis to CSeSi group) and between
CO2Me and Ph] were observed. These NOEs are also seen in the non-
deuterium-labelled cyclopropanes 3 [e.g., E = PO(OMe)2, R = Me].1e
In the non-deuterium-labelled cyclopropanes 3, J1,2 is 12.5 Hz. The
large coupling constant, together with considerations of molecular
models, suggests that the favoured dihedral angle ЄH-1–C-1–C-2–H-2
is close to 180Њ. By a combination of the suggested favoured structure
and observed NOEs, the relative stereochemistry of C-2,C-1 was
assigned as (R,R) or (S,S). The relative stereochemistry for a sulfone-
substituted cyclopropane prepared by this [2 ϩ 1] cycloaddition
method was recently confirmed by X-ray analysis.1f
Scheme 4 Alternative mechanism for cyclobutane formation with
ZnBr2. The carbon numbering of 1 and 6 corresponds to Scheme 3.
by straightforward methods and their [2 ϩ 1] and [2 ϩ 2]
reactions were examined. As a result, the cyclopropanation
sequence in Scheme 1, rather than that in Scheme 2, is strongly
supported by the labelling study reported herein. For cyclo-
butane formation, the possibility of silicon–selenium double
migration was eliminated, and it was unequivocally shown
that the metal-coordination site depends on the Lewis acid, and
controls the regiochemistry, as suggested before.5
On the regiochemistry of cyclobutanes, for example, the HMBC
correlations of H-2 ؒ ؒ ؒ CN for 7-1-d and H-2 ؒ ؒ ؒ CO2Me for 8-1-d
were observed. The stereochemistry of the Me3Si and PhSe groups
of cyclobutanes 7-1-d, 8-1-d, 7-2-d and 8-2-d was deduced as trans
according to the assignment of non-deuterium-labelled cyclobutanes
by NOESY spectra.5
1992
J. Chem. Soc., Perkin Trans. 1, 2000, 1991–1996

View Article Online
of 1-deuterio-2-phenylseleno-1-(trimethylsilyl)ethene 1-2-d
with phosphonoacrylate 2 gave a C-2 deuterio-substituted
cyclopropane product 3-2-d in 78% yield [equation (4)]. Thus,
in this case as well. The formation of cis-cyclopropane 5-2-d-cis
as a minor product may be explained by a steric isotope effect8
in C–C bond rotation in the zwitterion intermediate X (see
Scheme 1).
Next, [2 ϩ 2] cycloaddition reactions of deuterium-labelled
1 with dimethyl 2,2-dicyanoethene-1,1-dicarboxylate 6 were
examined [equations (7) and (8)]. The reaction of 1-deuterio-1-
(3)
(7)
(8)
(4)
phenylseleno-group migration as an alternative to silicon
migration is completely ruled out.
Reaction of vinyl ketones with 1 in the presence of SnCl4 led
totrans-cyclopropanespreferentially(Scheme1).Thereactionof
1-deuterio-1-phenylseleno-2-(trimethylsilyl)ethene 1-1-d with
methyl vinyl ketone 4 in the presence of SnCl4 at Ϫ78 ЊC gave
the C-1 deuterio-substituted trans-cyclopropane product 5-1-d
in 59% yield [equation (5)]. The reaction of 1-deuterio-2-
phenylseleno-1-(trimethylsilyl)ethene 1-2-d with 4 gave the C-2
deuterio-substituted cyclopropanes 5-2-d-trans and 5-2-d-cis in
48% yield (3.8:1 trans:cis ratio) [equation (6)]. Thus, phenyl-
seleno-group migration instead of silicon migration is ruled out
phenylseleno-2-(trimethylsilyl)ethene 1-1-d with 6 in the pres-
ence of SnCl4 at Ϫ78 ЊC gave C-1 deuterium-substituted
cyclobutane 7-1-d in 62% yield.‡ The reaction of 1-deuterio-
2-phenylseleno-1-(trimethylsilyl)ethene 1-2-d with 6 in the
presence of SnCl4 gave C-2 deuterium-substituted cyclobutane
7-2-d exclusively in 56% yield. Thus, the mechanism is in com-
plete agreement with that proposed previously (Scheme 3).
In contrast to the [2 ϩ 1] cycloaddition described above,
[2 ϩ 2] cycloaddition proceeds without silicon migration.
This result can be explained by destabilization of the corre-
sponding intermediate after silicon migration (I-CN2) and/or
the silicon-migration transition state (TS-CN2) by the two
electron-withdrawing cyano groups next to the cationic centre
(at C-4).
(5)
The reaction of deuterium-substituted 1 and 6 in the pres-
ence of ZnBr2 was also examined [equations (9) and (10)]. As a
result, the deuterium atoms on 1-1-d and 1-2-d stayed on the
original carbons adjacent to the heteroatoms. It was confirmed
that no silicon and selenium double migration as depicted in
Scheme 4 occurred. Thus, the regioselectivity was controlled by
the Lewis acid coordination sites as previously predicted.5
In summary, this labelling study strongly supports the previ-
ously proposed 1,2-silicon migration for [2 ϩ 1] cycloaddition
of 1 and non-1,2-silicon migration for [2 ϩ 2] cycloaddition,
respectively. The deuterium-substituted cyclopropanes and
cyclobutanes were stereoselectively prepared.
(6)
Experimental
General methods
Mps were measured on a Yamato MP-21 melting point appar-
atus and are uncorrected. IR spectra were recorded with a
JASCO FT-IR 5000 spectrophotometer. NMR spectra were
recorded on a Varian INOVA 400 spectrometer. Chemical shifts
are reported in ppm relative to Me4Si or residual non-
deuterated solvent. J-Values are given in Hz. 13C multiplicities
were determined by DEPT and HSQC. Mass spectra were
recorded on a JEOL JMS-01SG-2 spectrometer at an ionizing
J. Chem. Soc., Perkin Trans. 1, 2000, 1991–1996
1993

View Article Online
mmol) in THF (37 mL) with stirring. The solution was allowed
(9)
to warm to Ϫ30 ЊC slowly. After 2 h at Ϫ30 ЊC, the solution was
re-cooled to Ϫ78 ЊC. To the solution was added diphenyl disel-
enide (4.0 g, 12.8 mmol). The mixture was stirred at Ϫ78 ЊC
for 1 h, and then was allowed to warm to room temperature and
was stirred for 1.5 h. After the addition of water, the mixture
was extracted with hexane–diethyl ether (1:1). The organic
layer was dried over anhydrous MgSO4. The solvent was
removed at reduced pressure, and column chromatography (sil-
ica gel; hexane) of the residue gave 1-1-d (2.2 g, 68%) (Rf 0.5). 1-
1-d: Pale yellow oil; δH (400 MHz, CDCl3) 0.076 (9H, s, SiMe3),
6.18 (1H, t, JHD 2.7, H-2), 7.31–7.34 (3H, m, m,p-H of Ph) and
7.51–7.55 (2H, m, o-H of Ph). Non-deuterium-labelled com-
pound was not detected by 1H NMR analysis; δC (100.6 MHz,
CDCl3) Ϫ1.19 (SiMe3), 127.7 (CH), 129.3 (CH), 129.4 (CH),
133.8 (CH), 134.1 (CH) and 134.2 (t, JCD 28, C-1); νmax/cmϪ1
(neat) 2958, 1524, 1479, 1249, 861 and 837; m/z (EI) 257 (Mϩ);
exact mass Mϩ, 257.0222 (C11H15D80Se28Si requires M,
257.0250) (Found: C, 51.65; H ϩ D, 6.2%. Calc. for C11H15-
DSeSi: C, 51.55; H ϩ D, 6.3%).
(10)
(E)-2-Phenylseleno-1-(trimethylsilyl)[1-2H]ethene 1-2-d
1-2-d was prepared from 11-2-d by the same procedure as for
1-2-d in 67% yield as a pale yellow oil; δH (400 MHz, CDCl3)
0.070 (9H, s, SiMe3), 7.00 (1H, t, JHD 2.7, H-1), 7.30–7.34 (3H,
1
m, m,p-H of Ph) and 7.51–7.55 (2H, m, o-H of Ph). H NMR
analysis indicated 99% D incorporation; δC (100.6 MHz,
CDCl3) Ϫ1.20 (SiMe3), 127.8 (CH), 129.37 (C), 129.42 (CH),
133.8 (CH), 133.9 (t, JCD 21, C-2) and 134.4 (CH); νmax/cmϪ1
(neat) 2958, 1580, 1533, 1479, 1249, 967 and 841; m/z (EI) 257
(Mϩ) (Found: C, 51.5; H ϩ D, 6.3%. Calc. for C11H15DSeSi:
C, 51.55; H ϩ D, 6.3%).
voltage of 70 eV by EI. All reactions were carried out under a
nitrogen atmosphere.
(E)-1-Tributylstannyl-2-(trimethylsilyl)[1-2H]ethene 11-1-d§
Methyl r-1-(dimethoxyphosphoryl)-c-2-[(phenylseleno)(trimeth-
ylsilyl)[2H]methyl]cyclopropanecarboxylate 3-1-d§¶
A neat solution of n-Bu3SnH (6.36 g, 22.9 mmol) and ([2H]-
ethynyl)trimethylsilane6 10-d [prepared from (trimethylsilyl)-
ethynylmagnesium bromide and D2O (CEA, 99.9% D)] (2.90 g,
2.93 mmol) was heated at 100 ЊC for 24 h. The reaction mixture
was cooled and the product was distilled directly to give 11-1-d
(6.87 g, 77%) as a colourless oil; bp 105–110 ЊC/1 mmHg; δH (400
MHz, CDCl3) 0.056 (9H, s, SiMe3), 0.862–0.924 (15H, m),
1.26–1.37 (6H, m), 1.46–1.54 (6H, m) and 6.60 (1H, t, JHD 3.4,
To a solution of 1-1-d (256 mg, 1.00 mmol) in dichloromethane
(2.5 mL) was added SnCl4 (0.176 mL, 391 mg, 1.50 mmol),
followed by 2-phosphonoacrylate 2 (0.202 mL, 252 mg, 1.30
mmol) at Ϫ78 ЊC. The mixture was stirred at Ϫ78 ЊC for 3 h.
The reaction mixture was quenched by triethylamine (0.36 mL,
260 mg, 2.6 mmol) and then with saturated aq. NaHCO3. The
mixture was extracted with dichloromethane and the organic
phase was washed with water, dried (Na2SO4), and evaporated
in vacuo. The residue was purified by column chromatography
over silica gel and eluting with CH2Cl2–diethyl ether (2:1) to
give 3-1-d (340 mg, 76%) (Rf 0.5) as a pale yellow oil; δH (400
MHz, CDCl3) 0.104 (9H, s, SiMe3), 1.62 (1H, ddd, J 9.9, 8.1
and 4.5, H-4), 1.86 (1H, ddd, J 14.1, 8.7 and 4.5, H-4), 2.23 (1H,
ddd, J 14.2, 8.7 and 8.1, H-2), 3.40 (3H, s, CO2Me), 3.80 (3H, d,
J 11.0, POMe), 3.89 (3H, d, J 11.0, POMe), 7.19–7.23 (3H, m,
m,p-H of Ph) and 7.49–7.51 (2H, m, o-H of Ph); δC (100.6
MHz, CDCl3) Ϫ1.87 (SiMe3), 24.01 (d, JCP 3.1, C-4), 25.43
(d, JCP 191, C-3), 28.65 (t, JCD 20, CD), 33.42 (d, JCP 2.3, C-2),
52.66 (CO2Me), 53.55 (d, JCP 6.1, POMe), 53.66 (d, JCP 6.1,
POMe), 127.1 (CH), 128.9 (CH), 130.6 (C), 133.8 (CH) and
168.9 (d, JCP 7.6, CO); νmax/cmϪ1 (neat) 2958, 1721, 1578, 1479,
1437, 1307, 1251, 1036 and 841; m/z (EI) 456; exact mass Mϩ,
451.0576 (C17H26DO5P80Se28Si requires M, 451.0592).
1
H-2). H NMR analysis indicated 99% D incorporation; δC
(100.6 MHz; CDCl3) Ϫ1.39 (SiMe3), 9.49 (CH2), 13.79 (CH3),
27.35 (CH2), 29.19 (CH2), 149.5 (t, JCD 22, C-1) and 155.0 (C-2);
νmax/cmϪ1 (neat) 2960, 2928, 2874, 1464, 1247, 861 and 837; m/z
(EI) 334 (Mϩ Ϫ 55, 100%), 276 (13) and 73 (22).
(E)-2-Tributylstannyl-1-(trimethylsilyl)[1-2H]ethene 11-2-d
11-2-d was prepared from n-Bu3SnD7 [prepared from Bun SnCl
3
and LiAlD4 (Aldrich, 98% D)] and ethynyltrimethylsilane
by the same procedure as for 11-1-d in 79% yield as a colourless
oil; bp 100–110 ЊC/1 mmHg; δH (400 MHz, CDCl3) 0.056
(9H, s, SiMe3), 0.862–0.923 (15H, m), 1.26–1.35 (6H, m), 1.46–
1.54 (6H, m) and 6.95 (1H, t, JHD 3.4, H-1). Non-deuterium-
1
labelled compound was not detected by H NMR analysis;
δC (100.6 MHz, CDCl3) Ϫ1.40 (SiMe3), 9.50 (CH2), 13.80
(CH3), 27.35 (CH2), 29.19 (CH2), 149.8 (C-1) and 154.7 (t, JCD
21, C-2); νmax/cmϪ1 (neat) 2960, 2928, 2874, 2856, 1526, 1464,
1377, 1247 and 837; m/z (EI) 334 (Mϩ Ϫ 55, 100%), 278 (20)
and 73 (20).
Methyl r-1-(dimethoxyphosphoryl)-c-2-[(phenylseleno)(trimeth-
ylsilyl)methyl][2-2H]cyclopropanecarboxylate 3-2-d
3-2-d was prepared from 1-2-d by the same procedure for 3-1-d
in 78% yield as a pale yellow oil; δH (400 MHz, CDCl3) 0.106
(9H, s, SiMe3), 1.61 (1H, dd, J 9.9 and 4.5, H-4), 1.86 (1H, dd,
J 14.2 and 4.5, H-4), 2.59 (1H, s, CHSeSi), 3.39 (3H, s, CO2Me),
3.80 (3H, d, J 11.0, POMe), 3.89 (3H, d, J 11.0, POMe), 7.19–
(E)-1-Phenylseleno-2-(trimethylsilyl)[1-2H]ethene 1-1-d
A solution of 1.42 M n-BuLi (9.0 mL, 12.8 mmol) in hexane
was added to a pre-cooled (Ϫ78 ЊC) solution of (E)-1-
tributylstannyl-2-(trimethylsilyl)[1-2H]ethene 11-1-d (5.0 g, 12.8
1
§ The compound nomenclature in titles is systematic. The H and 13C
assignments follow the Schemes in the text.
¶ Non-deuterium-labelled compounds were not detected in the prod-
ucts by 1H NMR analysis.
1994
J. Chem. Soc., Perkin Trans. 1, 2000, 1991–1996

View Article Online
7.23 (3H, m, m,p-H of Ph) and 7.49–7.52 (2H, m, o-H of Ph);
δC (100.6 MHz, CDCl3) Ϫ1.86 (SiMe3), 23.95 (d, JCP 2.3, C-4),
25.33 (d, JCP 191, C-3), 28.89 (CHSeSi), 33.23 (t, JCD 25, C-2),
52.66 (CO2Me), 53.55 (d, JCP 6.1, POMe), 53.66 (d, JCP 6.1,
POMe), 127.1 (CH), 128.9 (CH), 130.7 (C), 133.8 (CH) and
168.9 (d, JCP 6.9, CO); νmax/cmϪ1 (neat) 2956, 1721, 1578, 1479,
1437, 1311, 1284, 1251, 1035, 839 and 741; m/z (EI) 451 (Mϩ);
exact mass Mϩ, 451.0595 (C17H26DO5P80Se28Si requires M,
451.0592).
followed by a solution of dimethyl 2,2-dicyanoethene-1,1-
dicarboxylate 64 (252 mg, 1.30 mmol) in CH2Cl2 (1.2 mL) at
Ϫ78 ЊC. The mixture was stirred at Ϫ78 ЊC for 1 h. The reaction
mixture was quenched by triethylamine (0.32 mL, 233 mg, 2.3
mmol) and then with saturated aq. NaHCO3. The mixture was
extracted with dichloromethane and the organic phase was
washed with water, dried (Na2SO4), and evaporated in vacuo.
The residue was purified by column chromatography over silica
gel and elution with hexane–diethyl ether (2:1) to give 7-1-d
(279 mg, 62%) (Rf 0.7) as colourless crystals; mp 78–80 ЊC; δH
(400 MHz, CDCl3) 0.239 (9H, s, SiMe3), 2.89 (1H, s, H-2), 3.85
(3H, s, CO2Me), 3.97 (3H, s, CO2Me), 7.30–7.38 (3H, m, m,p-H
of Ph) and 7.60–7.64 (2H, m, o-H of Ph); δC (100.6 MHz,
CDCl3) Ϫ2.57 (SiMe3), 33.29 (C-3), 38.91 (C-2), 41.91 (t, JCD
24, C-1), 53.73 (CO2Me), 53.84 (CO2Me), 67.96 (C-4), 112.6
(CN), 113.9 (CN), 128.7 (CH), 128.7 (C), 129.5 (CH), 134.5
(CH), 165.1 (CO) and 165.7 (CO); νmax/cmϪ1 (KBr) 2960, 2250,
1744, 1578, 1301, 1253 and 847; m/z (EI) 451; exact mass Mϩ,
451.0563 (C19H21DN2O480Se28Si requires M, 451.0576) (Found:
C, 50.8; H ϩ D, 4.7; N, 6.2%. Calc. for C19H21DN2O4SeSi: C,
50.7; H ϩ D, 4.9; N, 6.2%).
trans-1-Acetyl-2-{(phenylseleno)(trimethylsilyl)[2H]methyl}-
cyclopropane 5-1-d-trans
To a solution of 1-1-d (256 mg, 1.00 mmol) in dichloromethane
(2.5 ml) was added SnCl4 (0.176 mL, 391 mg, 1.50 mmol),
followed by methyl vinyl ketone 4 (0.108 mL, 91.1 mg, 1.30
mmol) at Ϫ78 ЊC. The mixture was stirred at Ϫ78 ЊC for 3 h.
The reaction mixture was quenched by triethylamine (0.36 mL,
260 mg, 2.6 mmol) and then with saturated aq. NaHCO3. The
mixture was extracted with dichloromethane and the organic
phase was washed with water, dried (Na2SO4), and evaporated
in vacuo. The residue was purified by column chromatography
over silica gel and elution with hexane–diethyl ether (4:1) to
give 5-1-d (340 mg, 59%) (Rf 0.5) as a pale yellow oil; δH (400
MHz, CDCl3) 0.166 (9H, s, SiMe3), 0.745 (1H, ddd, J 8.1, 6.4,
and 4.0, H-4), 1.32 (1H, ddd, J 8.7, 4.8 and 4.0, H-4), 1.53 (1H,
ddd, J 8.1, 4.8 and 3.9, H-3), 1.72 (1H, ddd, J 8.7, 6.4 and 3.9,
H-2), 1.93 (3H, s, COMe), 7.25–7.30 (3H, m, m,p-H of Ph) and
7.56–7.58 (2H, m, o-H of Ph); δC (100.6 MHz, CDCl3) Ϫ1.84
(SiMe3), 19.78 (C-4), 29.94 (C-2), 30.00 (C-3), 30.53 (COMe),
35.85 (t, JCD 19, CDSeSi), 127.5 (p-C of Ph), 129.1 (m-C of Ph),
130.6 (C of Ph), 134.5 (o-C of Ph) and 207.9 (CO); νmax/cmϪ1
(neat) 2958, 1698, 1578, 1390, 1249 and 843; m/z (EI) 327 (Mϩ,
24%), 170 (57), 96 (38) and 73 (100); exact mass Mϩ, 327.0638
(C15H21DO80Se28Si requires M, 327.0667) (Found: C, 55.2;
H ϩ D, 6.65%. Calc. for C15H21DOSeSi: C, 55.2; H ϩ D, 6.8%).
Dimethyl 3,4-trans-2,2-dicyano-4-phenylseleno-3-(trimethyl-
silyl)[3-2H]cyclobutane-1,1-dicarboxylate 7-2-d
7-2-d was prepared from 1-2-d by the same procedure used for
7-1-d in 56% yield [Rf 0.7 (hexane–diethyl ether 2:1)] as colour-
less crystals; mp 78–81 ЊC; δH (400 MHz, CDCl3) 0.240 (9H, s,
SiMe3), 3.85 (3H, s, CO2Me), 3.97 (3H, s, CO2Me), 4.31 (1H, s,
H-1), 7.31–7.38 (3H, m, m,p-H of Ph) and 7.61–7.64 (2H, m,
o-H of Ph); δC (100.6 MHz, CDCl3) Ϫ2.59 (SiMe3), 33.21 (C-3),
38.54 (t, JCD 21, C-2), 42.12 (C-1), 53.73 (CO2Me), 53.85
(CO2Me), 68.04 (C-4), 112.6 (CN), 113.9 (CN), 128.71 (CH),
128.74 (C), 129.5 (CH), 134.5 (CH), 165.1 (CO) and 165.7
(CO); νmax/cmϪ1 (KBr) 2960, 2370, 2334, 2248, 1744, 1578,
1296, 845 and 743; m/z (EI) 451; exact mass Mϩ, 451.0536
(C19H21DN2O480Se28Si requires M, 451.0576) (Found: C, 50.8;
H ϩ D, 4.9; N, 6.2%. Calc. for C19H21DN2O4SeSi: C, 50.7;
H ϩ D, 4.9; N, 6.2%).
trans-2-Acetyl-1-[(phenylseleno)(trimethylsilyl)methyl][1-2H]-
cyclopropane 5-2-d-trans and cis-2-acetyl-1-[(phenylseleno)-
(trimethylsilyl)methyl][1-2H]cyclopropane 5-2-d-cis
Reaction of 1-1-d and 6 with ZnBr2
5-2-d-trans and 5-2-d-cis were prepared from 1-2-d by the same
procedure used for 5-1-d in 38% and 10% yield, respectively.
5-2-d-trans [Rf 0.15 (hexane–diethyl ether 2:1)] was obtained as
colourless crystals; mp 40–42 ЊC; δH (400 MHz, CDCl3) 0.166
(9H, s, SiMe3), 0.740 (1H, dd, J 8.0 and 4.0, H-4), 1.31 (1H, dd,
J 4.5 and 4.5, H-4), 1.52 (1H, dd, J 8.0 and 5.0, H-3), 1.92 (3H,
s, COMe), 2.09 (1H, s, CHSeSi), 7.24–7.29 (3H, m, m,p-H of
Ph) and 7.56–7.58 (2H, m, p-H of Ph); δC (100.6 MHz, CDCl3)
Ϫ1.83 (SiMe3), 19.70 (C-4), 29.71 (t, JCD 25, C-2), 29.92 (C-3),
30.53 (COMe), 36.13 (CHSeSi), 127.5 (CH), 129.1 (CH), 130.6
(C), 134.4 (CH) and 207.9 (CO); νmax/cmϪ1 (KBr) 2960, 1692,
1576, 1383, 1249 and 839; m/z (EI) 327; exact mass Mϩ,
327.0640 (C15H21DO80Se28Si requires M, 327.0667) (Found: C,
55.1; H ϩ D, 6.5%. Calc. for C15H21DOSeSi: C, 55.2; H ϩ D,
6.8%).
5-2-d-cis [Rf 0.3 (hexane–diethyl ether 2:1)] was obtained as a
colourless oil; δH (400 MHz, CDCl3) 0.058 (9H, s, SiMe3), 1.21
(2H, d, J 6.4, H-4), 2.07 (3H, s, COMe), 2.15 (1H, dd, J 6.4 and
6.4, H-3), 2.66 (1H, s, CHSeSi), 7.19–7.23 (3H, m, m,p-H of Ph)
and 7.49–7.52 (2H, m, o-H of Ph); δC (100.6 MHz, CDCl3)
Ϫ1.74 (SiMe3), 18.60 (C-4), 27.21 (CH), 28.43 (CH), 29.24 (t,
JCD 25, C-2), 32.30 (COMe), 127.2 (CH), 128.9 (CH), 129.9 (C),
134.7 (CH) and 206.9 (CO); νmax/cmϪ1 (neat) 2958, 1692, 1578,
1479, 1381, 1249, 1176, 874 and 837; m/z (EI) 327; exact mass
Mϩ, 327.0652 (C15H21DO80Se28Si requires M, 327.0667).
To a solution of 1-1-d (255 mg, 1.00 mmol) in dichloromethane
(1.2 mL) was added ZnBr2 (338 mg, 1.50 mmol), followed by
a solution of dimethyl 2,2-dicyanoethene-1,1-dicarboxylate 6
(252 mg, 1.30 mmol) in CH2Cl2 (1.2 mL) at 0 ЊC. The mixture
was stirred at 0 ЊC for 5 h, then at room temperature for 2 h.
The reaction mixture was quenched by triethylamine (0.32 mL,
233 mg, 2.3 mmol) and then with saturated aq. NaHCO3. The
mixture was extracted with dichloromethane and the organic
phase was washed with water, dried (Na2SO4), and evaporated
in vacuo. The residue was purified by column chromatography
over silica gel and elution with hexane–diethyl ether (2:1) to give
8-1-d (43 mg, 10%) (Rf 0.7) and 9-1-d (220 mg, 58%) (Rf 0.6).
Dimethyl 3,4-trans-2,2-dicyano-3-phenylseleno-4-(trimethyl-
silyl)[3-2H]cyclobutane-1,1-dicarboxylate 8-1-d. Colourless oil;
δH (400 MHz, CDCl3) 0.112 (9H, s, SiMe3), 2.70 (1H, s, H-2),
3.85 (3H, s, CO2Me), 3.89 (3H, s, CO2Me), 7.34–7.40 (3H, m,
m,p-H of Ph) and 7.65–7.67 (2H, m, o-H of Ph); δC (100.6
MHz, CDCl3) Ϫ2.17 (SiMe3), 37.37 (C-2), 43.82 (t, JCD 25,
C-1), 44.81 (C-3), 53.84 (CO2Me), 53.91 (CO2Me), 60.78 (C-4),
111.8 (CN), 112.8 (CN), 127.1 (C), 129.3 (CH), 129.9 (CH),
135.1 (CH), 166.3 (CO) and 166.4 (CO); νmax/cmϪ1 (neat) 2958,
2270, 1754, 1736 and 1294; m/z (EI) 451; exact mass Mϩ,
451.0517 (C19H21DN2O480Se28Si requires M, 451.0576) (Found:
C, 50.7; H ϩ D, 4.8; N, 6.1%. Calc. for C19H21DN2O4SeSi: C,
50.7; H ϩ D, 4.9; N, 6.2%).
Dimethyl 3,4-trans-2,2-dicyano-4-phenylseleno-3-(trimethyl-
silyl)[4-2H]cyclobutane-1,1-dicarboxylate 7-1-d
Dimethyl 2,2-dicyano-3-(phenylseleno)[3-2H]cyclobutane-1,1-
dicarboxylate 9-1-d. Colourless oil; δH (400 MHz, CDCl3) 2.84
(1H, d, J 12.9, H-2), 2.91 (1H, d, J 12.9, H-2), 3.88 (3H, s,
To a solution of 1-1-d (256 mg, 1.00 mmol) in dichloromethane
(1.2 mL) was added SnCl4 (0.176 mL, 391 mg, 1.50 mmol),
J. Chem. Soc., Perkin Trans. 1, 2000, 1991–1996
1995

View Article Online
CO2Me), 3.90 (3H, s, CO2Me), 7.33–7.42 (3H, m, m,p-H of Ph)
and 7.64–7.67 (2H, m, o-H of Ph); δC (100.6 MHz, CDCl3)
33.93 (C-2), 40.22 (t, JCD 24, C-1), 42.17 (C-3), 54.00 (CO2Me),
54.56 (CO2Me), 58.01 (C-4), 111.79 (CN), 111.82 (CN), 126.3
(C), 129.4 (CH), 129.8 (CH), 135.4 (CH), 165.5 (CO) and 166.1
(CO); νmax/cmϪ1 (neat) 2962, 2344, 2250, 1746, 1578, 1437, 1288,
743 and 692; m/z (EI) 379 (Found: C, 50.85; H ϩ D, 3.8; N,
7.2%. Calc. for C16H13DN2O4Se: C, 50.8; H ϩ D, 3.7; N, 7.4%).
Reaction of 1-2-d and 6 with ZnBr2 by the same procedure
as used for 1-1-d gave 8-2-d and 9-2-d in 10% and 76% yield,
respectively.
111.80 (CN), 126.3 (C), 129.4 (CH), 129.8 (CH), 135.4 (CH),
165.4 (CO) and 166.1 (CO); νmax/cmϪ1 (neat) 2962, 1744, 1578,
1437, 1280, 743 and 692; m/z (EI) 379; exact mass Mϩ, 379.0159
(C16H13DN2O480Se requires M, 379.0181) (Found: C, 50.7;
H ϩ D, 3.6; N, 7.15%. Calc. for C16H13DN2O4Se: C, 50.8;
H ϩ D, 3.7; N, 7.4%).
Acknowledgements
We are grateful to Professor S. Yamabe for helpful discussions.
This work was supported by the Ministry of Education,
Science, Sports and Culture of the Japanese Government,
and by the Sumitomo Foundation.
Dimethyl
3,4-trans-2,2-dicyano-3-phenylseleno-4-(trimeth-
ylsilyl)[4-2H]cyclobutane-1,1-dicarboxylate 8-2-d. [Rf 0.7
(hexane–diethyl ether 2:1)]; colourless crystals; mp 65–68 ЊC; δH
(400 MHz, CDCl3) 0.000 (9H, s, SiMe3), 3.85 (3H, s, CO2Me),
3.89 (3H, s, CO2Me), 4.50 (1H, s, H-1), 7.34–7.40 (3H, m, m,p-H
of Ph) and 7.65–7.67 (2H, m, o-H of Ph); δC (100.6 MHz,
CDCl3) Ϫ2.20 (SiMe3), 37.04 (t, JCD 19, C-2), 44.04 (C-1), 44.87
(C-3), 53.83 (CO2Me), 53.91 (CO2Me), 60.69 (C-4), 111.8 (CN),
112.8 (CN), 127.2 (C), 129.3 (CH), 129.9 (CH), 135.0 (CH),
166.3 (CO) and 166.4 (CO); νmax/cmϪ1 (KBr) 2960, 2348, 1750,
1738, 1439, 1296, 1255 and 845; m/z (EI) 451; exact mass Mϩ,
451.0548 (C19H21DN2O480Se28Si requires M, 451.0576) (Found:
C, 50.5; H ϩ D, 4.8; N, 6.3%. Calc. for C19H21DN2O4SeSi: C,
50.7; H ϩ D, 4.9; N, 6.2%).
References
1 (a) S. Yamazaki, M. Tanaka, A. Yamaguchi and S. Yamabe, J. Am.
Chem. Soc., 1994, 116, 2356; (b) S. Yamazaki, M. Tanaka, T. Inoue,
N. Morimoto, H. Kumagai and K. Yamamoto, J. Org. Chem., 1995,
60, 6546; (c) S. Yamazaki, M. Tanaka and S. Yamabe, J. Org. Chem.,
1996, 61, 4046; (d) S. Yamazaki, H. Kumagai, T. Takada, S. Yamabe
and K. Yamamoto, J. Org. Chem., 1997, 62, 2968; (e) S. Yamazaki,
T. Takada, T. Imanishi, Y. Moriguchi and S. Yamabe, J. Org. Chem.,
1998, 63, 5919; ( f ) S. Yamazaki, Y. Yanase, E. Tanigawa, S. Yamabe
and H. Tamura, J. Org. Chem., 1999, 64, 9521.
2 S. Yamazaki and S. Yamabe, unpublished work.
3 For migration of the PhSe group, see: (a) D. L. J. Clive, G. Chittattu
and C. K. Wong, J. Chem. Soc., Chem. Commun., 1978, 441; (b) W. P.
Jackson, S. V. Ley and J. A. Morton, Tetrahedron Lett., 1981, 22,
2601; (c) S. Yamazaki, M. Hama and S. Yamabe, Tetrahedron Lett.,
1990, 31, 2918; (d) S. Yamazaki, W. Mizuno and S. Yamabe, J. Chem.
Soc., Perkin Trans. 1, 1991, 1555.
4 H. K. Hall, Jr. and R. C. Sentman, J. Org. Chem., 1982, 47, 4572.
5 S. Yamazaki, H. Kumagai, S. Yamabe and K. Yamamoto, J. Org.
Chem., 1998, 63, 3371.
6 M. A. Cook, C. Eaborn and D. R. M. Walton, J. Organomet. Chem.,
1970, 24, 301.
7 W. P. Neumann and R. Sommer, Angew. Chem., 1963, 75, 788.
8 B. K. Carpenter, Determination of Organic Reaction Mechanisms,
Wiley, New York, 1984, pp. 99–101.
Dimethyl 2,2-dicyano-3-(phenylseleno)[4-2H]cyclobutane-1,1-
dicarboxylate 9-2-d. 2:1 Diastereomixture (D:SePh = cis,
major). The observed NOEs were between δ 4.58 and 2.91 and
between δ 4.58 and 7.64–7.67. [Rf 0.6 (hexane–diethyl ether
2:1)]. Pale yellow oil; δH (400 MHz, CDCl3) 2.84 (0.33H, d,
J 11.4, H-2), 2.91 (0.69H, d, J 9.0, H-2), 3.88 (3H, s, CO2Me),
3.90 (3H, s, CO2Me), 4.58 (1H, br d, J 9.2, H-1), 7.33–7.42 (3H,
m, m,p-H of Ph) and 7.64–7.67 (2H, m, o-H of Ph); δC (100.6
MHz, CDCl3) 33.66 (t, JCD 22, C-2), 40.39 (C-1), 42.20 (C-3),
53.98 (CO2Me), 54.55 (CO2Me), 57.86 (C-4), 111.76 (CN),
1996
J. Chem. Soc., Perkin Trans. 1, 2000, 1991–1996