Asymmetric [2 + 1] cycloaddition reactions of 1-seleno-2-silylethene

Article abstract of DOI:10.1021/jo960194u

The reaction of (E)-1-(phenylseleno)-2-(trimethylsilyl)ethene (1) and vinyl ketones 2a-d in the presence of a chiral Lewis acid prepared from TiCl₄, Ti(OⁱPr)₄, (R)- or (S)-1,1′-binaphthol (BINOL), and MS4A gave enantiomeri

Full text of DOI:10.1021/jo960194u

4046
J . Org. Chem. 1996, 61, 4046-4050
Asym m etr ic [2 + 1] Cycloa d d ition Rea ction s of
1-Selen o-2-silyleth en e
Shoko Yamazaki,* Mayumi Tanaka, and Shinichi Yamabe
Department of Chemistry, Nara University of Education, Takabatake-cho, Nara 630, J apan
Received J anuary 30, 1996X
The reaction of (E)-1-(phenylseleno)-2-(trimethylsilyl)ethene (1) and vinyl ketones 2a -d in the
presence of a chiral Lewis acid prepared from TiCl4, Ti(OiPr)4, (R)- or (S)-1,1′-binaphthol (BINOL),
and MS4A gave enantiomerically enriched cis cyclopropane products 3a -d . The enantiomeric excess
and chemical yield varied depending on the ratio of TiCl4 and Ti(OiPr)4 to 1. Reproducible results
(43-47% ee/33-41% yields) for cis-1-acetyl-2-[(phenylseleno)(trimethylsilyl)methyl]cyclopropane
(3a ) were obtained using 1.1 equiv of TiCl4, 0.54-0.65 equiv of Ti(OiPr)4, and 1.65 equiv of BINOL.
The observed enantioselectivity was explained by consideration of the structure of the postulated
intermediates, alkoxy titanium-carbonyl complexes, via ab initio MO calculations.
The development of new synthetic methodology for
preparation of optically active cyclopropane derivatives
is an important objective. Recently, various methods for
the synthesis of cyclopropanes have been developed, in
part because the cyclopropyl group is found to be a basic
structural unit in a wide range of biologically active
natural and non-natural products.1 We have recently
reported a novel [2 + 1] cycloaddition synthesis of 1,2-
trans cyclopropanes by the combination of (E)-1-(phen-
ylseleno)-2-silylethenes and vinyl ketones in the presence
of SnCl4.2 It is of synthetic and mechanistic interest to
investigate the possibility of asymmetric synthesis in this
novel [2 + 1] cycloaddition. Herein, we report that the
reaction of (E)-1-(phenylseleno)-2-(trimethylsilyl)ethene
(1) and vinyl ketones 2a -d in the presence of a chiral
Lewis acid gave enantiomerically enriched 1,2-cis cyclo-
propane products 3a -d (eq 1). The Lewis acid was
prepared from TiCl4, Ti(OiPr)4, (R)- or (S)-1,1′-binaphthol
(BINOL), and MS4A. In order to understand the ob-
served enantioselectivity, the structure of a Lewis acid-
carbonyl complex was determined by ab initio MO
calculations, and a possible mechanism is discussed.
Asym m etr ic [2 + 1] Cycloa d d ition of 1. After
extensive experimentation involving screening of various
Lewis acids and chiral ligands, the best chiral Lewis acid
was prepared as follows: into a flask containing activated
powdered molecular sieves (MS4A)3 was added a solution
of TiCl4 and Ti(OiPr)4 in CH2Cl2 followed by (R)-BINOL.
The mixture was stirred for 1 h at room temperature and
then cooled to -78 °C. To the mixture were then added
successively a solution of 1 in CH2Cl2 and vinyl ketones
2a -d . The mixture was then warmed to -30 °C and
stirred for 4-5.5 h. Quenching with triethylamine gave
enantiomerically enriched cis cyclopropane products
3a -d as the major products. The chemical yield and
enantiomeric excess for 3a depended on the ratio of TiCl4
and Ti(OiPr)4 to 1 and varied from 12% (57% ee) to 45%
(26% ee) as shown in Table 1.4,5 Reproducible results
(43-47% ee/33-41% yields) for 3a were obtained using
1.1 equiv of TiCl4, 0.54-0.65 equiv of Ti(OiPr)4, and 1.65
equiv of BINOL (entries 5-7 in Table 1). The % ee of
the produced cyclopropanes 3a -d was determined by
HPLC analysis by using a chiral column (CHIRALCEL
OF).
The absolute configuration of 3a was determined by
conversion to two different known compounds 6 and 7
(vide infra) (eq 2). Thus, (+)-3a (29% ee) prepared using
(R)-BINOL was oxidized with NaIO4 in a THF-H2O
solution at room temperature to give the sila-Pummerer
product (+)-4. The aldehyde (+)-4 was further oxidized
X Abstract published in Advance ACS Abstracts, J une 1, 1996.
(1) For recent examples of asymmetric synthesis of cyclopropanes,
see: (a) Doyle, M. P.; Austin, R. E.; Bailey, A. S.; Dwyer, M. P.; Dyatkin,
A. B.; Kalinin, A. V.; Kwan, M. M. Y.; Liras, S.; Oalmann, C. J .; Pieters,
R. J .; Protopopova, M. N.; Raab, C. E.; Roos, G. H.; Zhou, Q.-L.; Martin,
S. F. J . Am. Chem. Soc. 1995, 117, 5763 and references cited therein.
(b) Charette, A. B.; Prescott, S.; Brochu, C. J . Org. Chem. 1995, 60,
1081 and references cited therein. (c) Denmark, S. E.; Christenson, B.
L.; Coe, D. M.; O’Connor, S. P. Tetrahedron Lett. 1995, 36, 2215.
Denmark, S. E.; Christensen, B. L.; O’Connor, S. P. Tetrahedron Lett.
1995, 36, 2219. (d) Salau¨n, J .; Baird, M. S. Curr. Med. Chem. 1995, 2,
511. (e) White, J . D. J . Am. Chem. Soc. 1995, 117, 6224. (f) White, J .
D.; Kim, T-S.; Mambu, M. J . Am. Chem. Soc. 1995, 117, 5612. (g)
Critcher, D. I.; Connolly, S.; Wills, M. Tetrahedron Lett. 1995, 36, 3763.
(h) Armstrong, R. W.; Maurer, K. W. Tetrahedron Lett. 1995, 36, 357.
Barrett, A. G. M.; Doubleday, W. W.; Kasdorf, K.; Tustin, G. J .; White,
A. J . P.; Williams, D. J . J . Chem. Soc., Chem. Commun. 1995, 407. (i)
Zhao, Y.; Yang, T.; Lee, M.; Lee, D.; Newton, M. G.; Chu, C. K. J . Org.
Chem. 1995, 60, 5236. (j) Hanessian, S.; Andreotti, D.; Gomtsyan, A.
J . Am. Chem. Soc. 1995, 117, 10393 and references cited therein.
(2) (a) Yamazaki, S.; Tanaka, M.; Yamaguchi, A.; Yamabe, S. J . Am.
Chem. Soc. 1994, 116, 2356. (b) Yamazaki, S.; Katoh, S.; Yamabe, S.
J . Org. Chem. 1992, 57, 4.
(3) Molecular sieves (MS4A) were dried overnight at 250 °C in
vacuum or at 350 °C in air before use. The effect of molecular sieves
on enantioselectivity in this reaction was not examined. For previous
examples of the use of molecular sieves in reactions of chiral titanium
alkoxides, see: (a) Hanson, R. M.; Sharpless, K. B. J . Org. Chem. 1986,
51, 1922. Gao, Y.; Hanson, R. M.; Klunder, J . M.; Ko, S. Y.; Masamune,
H.; Sharpless, K. B. J . Am. Chem. Soc. 1987, 109, 5765. (b) Narasaka,
K.; Iwasawa, N.; Inoue, M.; Yamada, T.; Nakashima, M.; Sugimori, J .
J . Am. Chem. Soc. 1989, 111, 5340. Narasaka, K.; Hayashi, Y.;
Shimadzu, H.; Niihata, S. J . Am. Chem. Soc. 1992, 114, 8869. (c)
Mikami, K.; Terada, M.; Nakai, T. J . Am. Chem. Soc. 1989, 111, 1940.
Mikami, K.; Terada, M.; Nakai, T. J . Am. Chem. Soc. 1990, 112, 3949.
Mikami, K.; Motoyama, Y.; Terada, M. J . Am. Chem. Soc. 1994, 116,
2812. (d) Seebach, D.; Dahinden, R.; Marti, R. E.; Beck, A. K.; Plattner,
D. A.; Ku¨hnle, F. N. M. J . Org. Chem. 1995, 60, 1788.
(4) All reactions were carried out using 1.0 mmol of 1. When TiCl4
and Ti(OiPr)4 were measured by volume using syringe, the method gave
3a -d with unreproducible % ee and chemical yield. Therefore, TiCl4
and Ti(OiPr)4 were measured by weight each time. All results shown
in Table 1 were obtained by the latter method.
(5) Using 0.68 equiv of TiCl4 and 0.55 equiv of Ti(OiPr)4 gave 3a in
very low chemical yields (5%, 68% ee).
S0022-3263(96)00194-6 CCC: $12.00 © 1996 American Chemical Society

[2 + 1] Cycloaddition Reactions of 1-Seleno-2-silylethene
J . Org. Chem., Vol. 61, No. 12, 1996 4047
Ta ble 1. Asym m etr ic [2 + 1] Cycloa d d ition of 1 a n d 2a -d (eq 1).
vinyl
ketone
TiCl4
(equiv)
Ti(OiPr)4
(equiv)
BINOL
(equiv)
% yield
% ee
3a -d
recovered
1 (%)
entry
3a -d a
1
2
3
4
5
6
7
8
9
2a
2a
2a
2a
2a
2a
2a
2a
2b
2c
2d
1.57
1.11
1.09
1.58
1.11
1.11
1.11
1.24
1.10
1.10
1.13
0.69
0.60
0.73
1.06
0.56
0.65
0.54
0.50
0.59
0.55
0.58
1.10 (R)
1.10 (R)
1.10 (R)
1.10 (R)
1.65 (R)
1.65 (R)
1.65 (S)
1.10 (R)
1.65 (R)
1.65 (R)
1.65 (R)
45b
35c
12c
36d
39c
33c
41c
46e
42c
27
26
44
57
30
44
47
43
32
43
33
40
9
22
44
22
32
49
35
14
25
26
45
10
11
4f
a
b
Isolated yield. 9% of trans cyclopropane isomer (0% ee, by HPLC using a chiral column (CHIRALCEL OG)) was also isolated. c A
d
trace amount of the trans cyclopropane isomer was produced but not isolated. 6% of the trans cyclopropane isomer was also isolated.
% ee was not determined. e 10% of the trans cyclopropane isomer was also isolated. % ee was not determined. f Purification by column
chromatography was difficult. Less than 15% of 3d was produced (1H NMR of crude product).
to carboxylic acid 5 by RuCl3-NaIO4.6 Treatment of 5
Sch em e 1
with diazomethane in ether gave the enantiomer of
known methyl ester (+)-6. (-)-6 was assigned as (1R,2S)
by comparison with the sign of optical rotation of known
(1S,2R)-(+)-6 and by chiral GC comparison with authen-
tic (1S,2R)-(+)-6.7 By GC, the enantiopurity of (-)-6
prepared from (+)-3a (29% ee) was determined to be 29%
ee, indicating retention of configuration in the transfor-
mation of 3a to 6. Furthermore, Wittig reaction of (+)-4
prepared from (+)-3a (44% ee) with salt-free triphenyl-
pentylidenephosphorane3,8 gave (+)-7 in 45% yield (45%
ee by GC). (1R,2S)-(-)-7 has been described by Meyers
and co-workers as an intermediate for a natural product,
dictyopterene C′.7 Both the measured optical rotations
and chiral GC indicate retention of configuration. Thus,
the absolute configuration of (+)-3a was assigned as
(1S,2R).
or s-trans conformation (vide post). Synclinal stereose-
lective addition (due to a stabilizing secondary orbital
interaction, Se- - -CdO) may affect the face-selectivity.
Subsequent 1,2-silicon migration, generation of a selenium-
bridged intermediate by minimum motion, and ring
closure give the cyclopropane 3. Cis selectivity was
observed with this Lewis acid; thus single-bond rotation
of C1-C3 as well as C2-C3 must be a slower process than
ring closure.2,10 Since the stereochemistry of the original
synclinal addition step is retained throughout this pro-
posed mechanism, the origin of the observed enantiose-
lectivity in 3 should arise from the first addition step.
The experimental results for 3a indicate that the major
approach of 1 should occur from the re face of C1 (for the
numbering, see Scheme 1).
The composition of Lewis acids generated under our
best conditions can be considered as follows. First, TiCl4
and Ti(OiPr)4 equilibrate to give a Ti(IV) species repre-
sented by (TiClx(OiPr)y),12 which then leads to a mixture
When (R,R)-diphenylethanediol (1.65 equiv) was used
as a chiral ligand with TiCl4 (1.1 equiv) and Ti(OiPr)4
(0.55 equiv) in eq 1 instead of (R)-BINOL, (1R,2S)-3a was
obtained with lower % ee and chemical yield (13% ee/
16% yield). Use of TiBr4 instead of TiCl4 using (R)-
BINOL gave (1R,2S)-3a with only 7% ee (25% yield).
Or igin of En a n tioselectivity in [2 + 1] Cycloa d -
d ition of 1. In order to understand the observed
enantioselectivity in this [2 + 1] cycloaddition reaction
of 1, the total reaction mechanism was depicted as
previously discussed in systems with achiral ligands
(Scheme 1).2,9 In the first step, a chiral titanium-vinyl
ketone complex will be attacked by selenosilyl nucleophile
1. The titanium-vinyl ketone complex can adopt an s-cis
(9) Relative stereochemistry of C2 and CH(SePh)(SiMe3) in 3a (for
numbering, see eq 2) is determined as (R,R) by 2D-NOESY. See ref 8
in the following paper: Yamazaki, S.; Tanaka, M.; Inoue, T.; Morimoto,
N.; Kumagai, H.; Yamamoto, Y. J . Org. Chem. 1995, 60, 6546.
(10) Lewis acid dependence in the cis-trans selectivity in these [2
+ 1] cycloadditions has been observed earlier, as follows, and still
remains unclear, although mechanistic interpretation is underway.
AlCl3 (-78 °C),2 TiCl4 (1.1 equiv)/Ti(OiPr)4 (0.55 equiv)/(()-BINOL (1.65
equiv) (-30 °C), or TiCl4 (1.1equiv)/Ti(OiPr)4 (0.59 equiv) (-78 °C),11
gave cis cyclopropane predominantly. SnCl4 (-78 °C),2 TiCl4 (2.2 equiv)/
Ti(OiPr)4 (1.1 equiv) (-78 °C),11 or TiCl4-PPh3 (-78 °C)11 gave trans
cyclopropane predominantly.
(6) Carlsen, P. H. J .; Katsuki, T.; Martin, V. S.; Sharpless, K. B. J .
Org. Chem. 1981, 46, 3936.
(7) Romo, D.; Romine, J . L.; Midura, W.; Meyers, A. I. Tetrahedron
1990, 46, 4951.
(8) Bestmann, H.; Stransky, W.; Vostrowsky, O. Chem. Ber. 1976,
109, 1694.
(11) Yamazaki, S.; Tanaka, M. Unpublished results.

4048 J . Org. Chem., Vol. 61, No. 12, 1996
Yamazaki et al.
of TiCl2((R)-BINOLate) and (TiClx′(OiPr)y′) with evolution
of HCl and alcohol exchange by addition of (R)-BINOL
in the presence of MS4A (eq 3).3c In our best, reproduc-
ible conditions (TiCl4 (1.1 equiv), Ti(OiPr)4 (0.56-0.65
equiv), and (R)-BINOL (1.65 equiv)), TiCl2((R)-BINOLate)
is the major Lewis acid.13,14
F igu r e 1. Ab initio RHF/LANL1MB-optimized17,18 geometry
of TiCl2(R-BINOLate)-2a , A (R ) Me). Positions of all atoms
are fully optimized. The bold arrow indicates the approach
from re face of C1 of the methyl vinyl ketone ligand.
Addition of a vinyl ketone to the Lewis acid system
leads to a chiral titanium-vinyl ketone complex. The
structure of this chiral complex is probably the origin of
the observed enantioselectivity. Recently, the structure
of a complex of chiral alkoxytitanium with a bidentate
R,â-unsaturated carbonyl compound, which is postulated
as the intermediate in an asymmetric Diels-Alder reac-
tion, was elucidated by X-ray analysis and the reaction
mechanism discussed.15 However, the structure of a
complex of alkoxytitanium with monodentate carbonyl
compounds such as aldehydes and vinyl ketones (those
described in this paper) is still unknown. There are
several possibilities for the coordination structure of a
complex of titanium with vinyl ketone 2. These possibili-
ties were examined by the use of model systems and ab
inito calculations (see supporting information, part II).
For the model H (see Scheme 5 and Figures 6 and 7 of
supporting information, part II), ethylene glycoxide was
replaced by (R)-BINOLate.16 The geometry of the pos-
tulated TiCl2((R)-BINOLate)-methyl vinyl ketone (2a )
complex, A (R ) Me), was fully optimized. Restricted
Hartree-Fock (RHF) calculations with the LANL1MB
basis set were carried out for geometry optimizations.
LANL1MB consists of the effective core (pseudo) potential
of inner-shell electrons and valence minimal basis set.17
The RHF/LANL1MB was found to verify the reaction
mechanism of systems containing metal-chloride coor-
dination bonds.2a All the molecular orbital calculations
were performed, using Gaussian 92 and 94 program
packages.18 The obtained structure is shown in Figure
1. Cartesian coordinates and other computational details
are given in the supporting information (part III). In
Figure 2, the proposed synclinal approaches of 1 to A (R
) Me) from the si face and re face of C1 are outlined,
where C3- - -C2 and OdC- - -Se distances are set to ca.
3.0 Å. The approach from the si face of C1 shows steric
repulsion of C1 between the upper portion of the naph-
thalene ring and the Si(CH3)3 group. In contrast, ap-
proach from the re face of C1 seems to be free of steric
repulsion. This indicates that A (R ) Me) should be
attacked by the selenosilylethene nucleophile 1 from the
re face of C1 of methyl vinyl ketone (for numbering, see
eq 4). The conclusion of this discussion is consistent with
the experimental observation that the preferred isomer
for 3a is the (1S,2R) isomer when (R)-BINOL is used.
However, the observed moderate enantioselectivity may
partially result from competing cyclopropane formation
(12) Dijkgraaf, C.; Roussrau, J . P. G. Spectrochim. Acta A 1968, 2,
1213.
(13) In practice, TiCl2(R-BINOLate) may exist in dimeric form, as
shown in eq 5. The dimer may be weakly bound and readily dissociated
to a monomer.14
(14) (a) Duthaler, R. O.; Hafner, A. Chem. Rev. 1992, 92, 807, and
references cited therein. (b) Watenpaugh, K.; Caughlan, C. N. Inorg.
Chem. 1966, 5, 1782. (c) Terada, M.; Mikami, K.; Nakai, T. J . Chem.
Soc., Chem. Commun. 1990, 1623.
(15) (a) Gothelf, K. V.; Hazell, R. G.; J ørgensen, K. A. J . Am. Chem.
Soc. 1995, 117, 4435. (b) Gothelf, K. V.; J ørgensen, K. A. J . Org. Chem.
1995, 60, 6847. See also: (c) Haase, C.; Sarko, C. R.; DiMare, M. J .
Org. Chem. 1995, 60, 1777. Reference 3d.
(16) Although we have considered a hexacoordinate (Lewis acid:
carbonyl compound ) 1:2) form by the use of model compounds
(formaldehyde as a carbonyl compound, see Figure 4 in supporting
information, part II), TiCl2(R-BINOLate)-(2)2 must be sterically
crowded. Also, in view of the stoichiometry of TiCl2(R-BINOLate) and
2, TiCl2(R-BINOLate)-(2)2 will be in very low concentration, even if
it is produced. Furthermore, in view of the reactivity of a carbonyl
compound, dicoordinate vinyl ketones must be less reactive than
monocoordinate vinyl ketones.
(17) (a) Hay, P. J .; Wadt, W. R. J . Chem. Phys. 1985, 82, 270. (b)
Wadt, W. R.; Hay, P. J . J . Chem. Phys. 1985, 82, 284. (c) Hay, P. J .;
Wadt, W. R. J . Chem. Phys. 1985, 82, 299.
(18) (a) Frisch, M. J .; Trucks, G. W.; Head-Gordon, M.; Gill, P. M.
W.; Wong, M. W.; Foresman, J . B.; J ohnson, B. G.; Schlegel, H. B.;
Robb, M. A.; Repologle, E. S.; Gomperts, R.; Andreas, J . L.; Ragha-
vachrni, K.; Binkley, J . S.; Gonzalez, C.; Martin, R. L.; Fox, D. J .;
DeFrees, D. J .; Baker, J .; Stewart, J . J . P.; Pople, J . A. Gaussian 92,
Revision C; Gaussian, Inc., Pittsburgh, PA, 1992. (b) Frisch, M. J .;
Trucks, G. W.; Schlegel, H. B.; Gill, P. M. W.; J ohnson, B. G.; Robb,
M. A.; Cheeseman, J . R.; Keith, T.; Petersson, G. A.; Montgomery, J .
A.; Raghavachari, K.; Al-Laham, M. A.; Zakrzewski, V. G.; Ortiz, J .
V.; Foresman, J . B.; Cioslowski, J .; Stefanov, B. B.; Nanayakkara, A.;
Challacombe, M.; Peng, C. Y.; Ayala, P. Y.; Chen, W.; Wong, M. W.;
Andres, J . L.; Replogle, E. S.; Gomperts, R.; Martin, R. L.; Fox, D. J .;
Binkley, J . S.; Defrees, D. J .; Baker, J .; Stewart, J . J . P.; Head-Gordon,
M.; Gonzalez, C.; Pople, J . A. Gaussian 94, Revision B.1, Gaussian,
Inc., Pittsburgh, PA, 1995. Ab initio calculations using Gaussian 92
and 94 were made on the Convex spp1200/XA at the Information
Processing Center (Nara University of Education).

[2 + 1] Cycloaddition Reactions of 1-Seleno-2-silylethene
J . Org. Chem., Vol. 61, No. 12, 1996 4049
Sch em e 2
for 3a -d . GC analysis was performed using a Chiraldex B-PH
(20 m × 0.25 mm i.d.) column with flame-ionization detectors
and He as carrier gas. Optical rotations were measured with
a 1 cm × 5 cm cell. All reactions were carried out under a
nitrogen atmosphere.
Typ ica l Exp er im en ta l P r oced u r e Usin g TiCl4-Ti(O-
iP r )4-(R)-BINOL/MS4A in Ta ble 1 (En tr y 6). A typical
experimental procedure is described for entry 6 in Table 1. To
a flask containing MS4A (1.3 g) were added a solution of TiCl4
(212 mg, 1.11 mmol) and Ti(OiPr)4 (184 mg, 0.65 mmol) in
dichloromethane (1.7 mL), followed by (R)-BINOL (472 mg,
1.65 mmol), and the mixture was stirred at room temperature
for 1 h. To the mixture cooled to -78 °C was added a solution
of 1 (255 mg, 1.0 mmol) in dichloromethane (0.4 mL), followed
by 2a (0.11 mL, 1.3 mmol). The mixture was warmed to -30
°C and stirred for 4 h. The reaction was quenched by
triethylamine (0.32 mL, 2.3 mmol), and then saturated aque-
ous NaHCO3 was added to the mixture. 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 eluting with hexane-ether (2:1) to give recovered 1 (125
mg, 49%) and the product 3a (109 mg, 33%) (47% ee by HPLC
analysis) (Rf ) 0.4).
F igu r e 2. Proposed synclinal approaches of 1 to A (R ) Me).
For the structure of 1, standard bond lengths and bond angles
are used. C3- - -C2 and OdC- - -Se distances are set to 3.0-
3.1 Å.
promoted by the achiral complexes also present in the
reaction of general formula TiClx′(OiPr)y′ (see eq 3).
(1S,2R)-(+)-1-Acetyl-2-[(p h en ylselen o)(tr im eth ylsilyl)-
m eth yl]cyclop r op a n e (3a ): 1H NMR of 3a was identical with
that reported previously;2 HPLC (hexane-iPrOH ) 200:1)
minor peak tR1 14.3 min, major peak tR2 23.0 min; optical
rotation for 3a was measured for a sample whose ee% was
determined as 21%ee by HPLC analysis, [R]23D ) +19° (c 0.84,
CHCl3).
(1R,2S)-(-)-3a . (entry 7 in Table 1): HPLC (hexane-iPr-
OH ) 200:1) major peak tR1 14.5 min, minor peak tR2 23.9 min,
43% ee; [R]24 ) -36° (c 1.33, CHCl3).
D
(+)-cis-1-P r op ion yl-2-[(p h en ylselen o)(tr im eth ylsilyl)-
m eth yl]cyclop r op a n e (3b) (entry 9 in Table 1) (Rf ) 0.6
(hexane:ether ) 2:1)): pale yellow oil; HPLC (hexane-iPrOH
) 200:1) minor peak tR1 10.4 min, major peak tR2 12.5 min,
Poor results of [2 + 1] cycloadditions with vinyl ketone
t
2d (R ) Bu) (entry 11 in Table 1) can be explained as
follows. The synclinal approach of 1 to A (R ) tBu) from
the re side of C1 is retarded by steric hindrance between
the tBu group and phenyl ring (Scheme 2), indicating that
size limitations exist in the choice of R.
We have shown clearly that ab initio RHF/LANL1MB
calculations can be applied to complex asymmetric reac-
tions involving large molecules such as binaphthol in this
work. Further work is in progress on the design of
reactions of 1 with more reactive electrophilic olefins in
the presence of suitable chiral Lewis acids.
43% ee; [R]24 ) +38° (c 1.40, CHCl3); 1H NMR (200 MHz,
D
CDCl3) δ (ppm) 0.063 (s, 9H), 0.928 (t, J ) 7.2 Hz, 3H), 1.20-
1.27 (m, 2H), 1.66 (dddd, J ) 12.2, 8.1, 8.0, 8.0 Hz, 1H), 2.17
(ddd, J ) 8.1, 7.0, 6.1 Hz, 1H), 2.46 (q, J ) 7.2 Hz, 2H), 2.67
(d, J ) 12.0 Hz), 7.21-7.26 (m, 3H), 7.49-7.54 (m, 2H); 13C
NMR (50.1 MHz, CDCl3) δ (ppm) -1.705, 7.988, 18.35, 26.53,
28.49, 29.01, 38.18, 127.2, 128.8, 130.1, 134.5, 209.4; IR (neat)
3060, 2958, 2900, 1694, 1578, cm-1; MS (70 eV) m/z 340 (M+);
exact mass M+ 340.0776 (calcd for C16H24OSeSi 340.0761).
(+)-cis-1-H exa n oyl-2-[(p h en ylselen o)(t r im et h ylsilyl)-
m eth yl]cyclop r op a n e (3c) (entry 10 in Table 1) (Rf ) 0.6
(hexane:ether ) 2:1)): pale yellow oil; HPLC (hexane-iPrOH
) 400:1) minor peak tR1 12.7 min, major peak tR2 14.5 min,
Exp er im en ta l Section
Gen er a l Meth od s. IR spectra were recorded in the FT-
mode. NMR spectra were recorded in CDCl3 at 200 MHz.
Chemical shifts are reported in ppm relative to Me4Si or
residual nondeuterated solvent. Mass spectra were deter-
mined by electron impact. HPLC analysis was performed with
a UV detector (detection, 254 nm light) and a flow rate of 0.5
mL/min using a CHIRALCEL OF (0.46 cm × 25 cm) column
33% ee; [R]24 ) +24° (c 1.02, CHCl3); 1H NMR (200 MHz,
D
CDCl3) δ (ppm) 0.063 (s, 9H), 0.851 (t, 6.7 Hz, 3H), 1.19-1.75
(m, 9H), 2.15 (dd, J ) 7.1, 7.1 Hz, 1H), 2.36-2.47 (m, 2H),
2.70 (d, J ) 12.0 Hz, 1H), 7.20-7.24 (m, 3H), 7.49-7.53 (m,
2H); 13C NMR (50.1 MHz, CDCl3) δ (ppm) -1.734, 14.00, 18.50,
22.56, 23.52, 26.56, 28.28, 29.10, 31.40, 45.07, 127.1, 128.8,
130.1, 134.4, 209.1; IR (neat) 2958, 1692, 1578 cm-1; MS (70

4050 J . Org. Chem., Vol. 61, No. 12, 1996
Yamazaki et al.
eV) m/z 382 (M+); exact mass M+ 382.1234 (calcd for C19H30
OSeSi 382.1231).
-
peak tR1 ) 16.4 min, major peak tR2 ) 16.9 min, GC analysis
of (1S,2R)-(+)-6 prepared according to the literature7 was
(+)-cis-1-P iva loyl-2-[(p h en ylselen o)(t r im et h ylsilyl)-
m eth yl]cyclop r op a n e (3d ) (entry 11 in Table 1) (Rf ) 0.65
(hexane:ether ) 2:1)): pale yellow oil; HPLC (hexane-iPrOH
identical with tR1;
1H NMR (200 MHz, CDCl3) δ (ppm) 1.24
(ddd, 4.9, 4.9, 8.2 Hz, 1H), 1.71 (ddd, 4.9, 4.9, 6.6 Hz, 1H),
2.06-2.32 (m, 2H), 2.28 (s, 3H), 3.69 (s, 3H); 13C NMR (50.1
MHz, CDCl3) δ (ppm) 12.60, 23.23, 28.78, 30.73, 52.19, 170.5,
204.0; IR (neat) 2958, 1736, 1441 cm-1; MS (70 eV) m/z
(relative intensity) 142 (19) M+, 127 (100), 111 (32), 110 (80),
100 (9.5), 99 (9.0), 69 (13); exact mass M+ 142.0632 (calcd for
C7H10O3 142.0630).
) 400:1) minor peak tR1 9.4 min, major peak tR2 11.1 min, 40%
1
ee; [R]24 ) +31° (c 0.15, CHCl3); H NMR (200 MHz, CDCl3)
D
δ (ppm) 0.016 (s, 9H), 1.09-1.37 (m, 2H), 1.20 (s, 9H), 1.63
(dddd, J ) 12.4, 7.9, 7.9, 7.8 Hz, 1H), 2.42 (ddd, J ) 7.8, 5.7,
5.7 Hz, 1H), 2.80 (d, J ) 12.4 Hz, 1H), 7.18-7.28 (m, 3H),
7.45-7.50 (m, 2H); 13C NMR (50.1 MHz, CDCl3) δ (ppm)
-1.705, 20.05, 22.21, 26.82, 27.58, 28.86, 44.63, 126.7, 128.8,
130.8, 133.4, 214.0; IR (neat) 2968, 1684, 1580 cm-1; MS (70
(1S,2R)-(+)-(Z)-1-Acetyl-2-(1′-pen ten yl)cyclopr opan e (7).
(+)-4 (prepared from (+)-3 (44% ee)) (130.6 mg, 1.16 mmol)
was dissolved in 4.6 mL of THF and cooled to -78 °C. To this
solution was added 4.6 mL (1.27 mmol) of a 0.275 M THF
solution of salt-free triphenylpentylidenephosphorane.7,8 The
resulting mixture was allowed to warm to room temperature
and stirred overnight. Water was added to the mixture. The
mixture was extracted with ether (3×). The ethereal extracts
were washed with brine and then dried (MgSO4) and concen-
trated in vacuo. The residue was purified by column chroma-
tography over silica gel eluting with hexane-ether (2:1) to give
7 (45% ee by GC analysis, 86.9 mg, 45%) (Rf ) 0.4). 7:
eV) m/z 368 (M+); exact mass M+ 368.1038 (calcd for C18H28
OSeSi 368.1074).
-
(1S,2R)-(+)-1-Acetyl-2-for m ylcyclop r op a n e (4) in eq 2.
To a solution of (+)-3a (33% ee, 100 mg, 0.307 mmol) in THF
(5.3 mL) and H2O (0.71 mL) was added NaIO4 (154 mg, 0.718
mmol). The mixture was stirred vigorously for 2 h. The
reaction mixture was poured into ether and saturated aqueous
NaHCO3 solution and extracted with ether (×3). The com-
bined organic layer was dried (MgSO4) and concentrated in
vacuo (with ice-cooling). Distillation of the residue gave 4 (32
mg, ca. 93%, including a trace amount of impurity (PhSeSePh
colorless oil; [R]23 ) +182° (c 0.87, CHCl3) (reported optical
D
rotation for (1R,2S)-(-)-7, [R]22 ) -390° (c 1.54, CHCl3)7);
D
1
by H NMR). 4: colorless oil; bp 60-70 °C/20-21 mmHg; 1H
GC (90 °C) minor peak tR1 ) 15.2 min, major peak tR2 ) 16.2
min; 1H NMR (200 MHz, CDCl3) δ (ppm) 0.903 (t, J ) 6.7 Hz,
3H), 1.13-1.23 (m, 1H), 1.32-1.39 (m, 4H), 2.11-2.30 (m, 4H),
2.23 (s, 3H), 5.19 (dd, J ) 9.8, 10.3 Hz, 1H), 5.45 (td, J ) 7.2,
10.3 Hz, 1H); 13C NMR (50.1 MHz, CDCl3) δ (ppm) 14.06,
15.26, 22.18, 22.38, 27.34, 29.10, 31.84, 125.8, 132.3, 206.0;
IR (neat) 2962, 2930, 1700 cm-1; MS (70 eV) m/z 166 (M+);
exact mass M+ 166.1353 (calcd for C11H18O 166.1357).
NMR (200 MHz, CDCl3) δ (ppm) 1.52 (ddd, J ) 4.6, 4.6, 8.0
Hz, 1H), 1.93-2.17 (m, 2H), 2.36 (s, 3H), 2.54 (ddd, J ) 6.7,
6.7, 8.0 Hz, 1H), 9.28 (d, J ) 6.4 Hz, 1H); 13C NMR (50.1 MHz,
CDCl3) δ (ppm) 14.59, 30.44, 31.55, 32.34, 199.7, 204.9; IR
(neat) 1705 cm-1; MS (25 eV) m/z 112 (M+); exact mass M+
112.0517 (calcd for C6H8O2 112.0524); optical rotation was
measured for samples which were prepared from (+)-3a (20%
23
ee), [R]23 ) +21° (c 0.16, CH2Cl2), and (-)-3a (25% ee), [R]D
D
) -22° (c 0.26, CH2Cl2).
Ack n ow led gm en t. We are grateful to Dr. K. Yama-
moto (Osaka University) for measurement of mass
spectra. We also thank Dr. M. Katoh (Nara Women’s
University) for measurement of optical rotation and Dr.
N. Chatani and Dr. Kakiuchi (Osaka University) for
chiral GC analyses.
(1R,2S)-(+)-Meth yl 2-Acetylcyclop r op a n e-1-ca r boxy-
la te (6) in eq 2. A flask was charged with CCl4 (3 mL), MeCN
(3 mL), water (3 mL), compound (+)-4 (prepared from (+)-3a
(29% ee) (59 mg, 0.526 mmol)), and NaIO4 (783 mg, 3.66 mmol).
To the mixture was added ruthenium trichloride hydrate (11
mg, ∼0.053 mmol), and the reaction mixture was stirred
vigorously for 1 h at room temperature. Water was added,
and the the mixture was extracted three times with CH2Cl2.
The combined organic extracts were dried (Na2SO4) and
concentrated to give crude (1R,2S)-2-acetylcyclopropane-1-
carboxylic acid (5) (21 mg, ca. 31%). The low yield probably
comes from the volatility of the starting material 4. The
reaction was not optimized. Immediate treatment of crude 5
(21 mg, 0.164 mmol) with diazomethane in ether and purifica-
tion by column chromatography (silica gel, hexane-ether (1:
4)) gave 6 (29% ee by GC analysis, 17 mg, 73% yield from crude
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
spectra for compounds 3b-d , 4, 6 and 7, results of theoretical
analyses of model coordination compounds, and Z-matrix of
TiCl2(R-BINOLate)-2a , A (R ) Me) (33 pages). This material
is contained in libraries on microfiche, immediately follows this
article in the microfilm version of the journal, and can be
ordered from the ACS; see any current masthead page for
ordering information.
5) (Rf ) 0.4). 6: colorless oil; [R]21 ) -8°; GC (85 °C) minor
J O960194U
D