Chirality transfer during the [2,3]-sila-Wittig rearrangement and cyclopropanation reaction of optically active [(sec-allyloxy)silyl]lithiums

Full text of DOI:10.1021/ja003749i

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J. Am. Chem. Soc. 2001, 123, 3143-3144
3143
Scheme 1a
Chirality Transfer during the [2,3]-sila-Wittig
Rearrangement and Cyclopropanation Reaction of
Optically Active [(sec-Allyloxy)silyl]lithiums
Atsushi Kawachi,* Hirofumi Maeda, Hiroshi Nakamura,
Noriyuki Doi, and Kohei Tamao*
Institute for Chemical Research
Kyoto UniVersity, Uji, Kyoto 611-0011, Japan
ReceiVed October 23, 2000
Intramolecular reactions of organolithium reagents with olefins
have been extensively studied in organic synthesis. One repre-
sentative reaction is the Wittig rearrangement1 of R-alkoxy-
organolithium compounds, which provides a versatile method for
the regio- and stereoselective C-C bond formation along with
the allylic transposition. Another topic is the intramolecular
carbolithiation of olefins,2 which allows regio- and stereoselective
cyclizations. Much attention has recently been paid to asymmetric
variants of these reactions.1b-e,2a-d
In contrast to this, less attention has been paid to the
intramolecular reactions of silyllithium reagents3 with olefins
despite the potential utility for the regio- and stereoselective Si-C
bond formations. Recently, we found two reaction modes for the
intramolecular rearrangements of the [(sec-allyloxy)dimesitylsilyl]-
lithiums,4 as shown in eq 1. One is the [2,3]-sila-Wittig rear-
a (a) n-BuLi (×2), THF, 0 °C, 3 h. (b) 5% NH4Cl aq.
allylsilane (R)-(E)-2 in 88% yield with 97% ee.11 In contrast, (S)-
(Z)-1 (98% ee) afforded the allylsilane (S)-(E)-2 in 87% yield
with 96% ee. Thus, the resulting stereochemistry of the new chiral
center significantly depends on the olefin geometry of the
substrate, while the resulting olefin geometry is always E.
These aspects provide an insight into the mechanism,12 as
shown in Scheme 2. For instance, the silyllithium (S)-(E)-3 derived
from (S)-(E)-1 undergoes suprafacial attack on the olefin in the
lower-energy conformer (S)-(E)-3a, to give the observed (R)-(E)-
2, whereas the higher energy conformer (S)-(E)-3b due to the
allylic strain would provide (S)-(Z)-2, but this is not experimen-
tally observed. This is consistent with the general attributes of
the [2,3]-Wittig rearrangement.1a
(7) Synthesis of optically active allylsilanes: (a) For a review; Sarkar, T.
K. Synthesis 1990, 969 and 1101. (b) Catalytic asymmetric cross-coupling of
R-(silyl)alkyl Grignard reagents with alkenyl bromides; Hayashi, T.; Konishi,
M, Okamoto, Y.; Kabeta, K.; Kumada, M. L. J. Org. Chem. 1986, 51, 3772.
(c) Claisen rearrangement of optically active allylic alcohol derivatives; Sparks,
M. A.; Panek, J. S. J. Org. Chem. 1991, 56, 3431. (d) Nucleophilic substitution
of optically active allyl esters and carbamates with (organosilyl)cuprates;
Fleming, I.; Higgins, D.; Lawrence, N. J.; Thomas, A. P.; J. Chem. Soc., Perkin
Trans. 1 1992, 3331. (e) Wittig olefination of optically active R-silylaldehydes;
Bhushan, V.; Lohray, B. B.; Enders, D. Tetrahedron Lett. 1993, 34, 5067. (f)
Catalytic asymmetric hydrosilylation of 1,3-dienes; Hayashi, T.; Matsumoto,
Y.; Morikawa, I.; Ito, Y. Tetrahedron Asymmetry 1990, 1, 151. (g) Hatanaka,
Y.; Goda, K.; Yamashita, F.; Hiyama, T. Tetrahedron Lett. 1994, 35, 7981.
(h) Catalytic asymmetric silylation of allylic chlorides with chlorodisilanes;
Hayashi, T.; Ohno, A.; Lu, S.-J.; Matsumoto, Y.; Fukuyo, E.; Yanagi, K.; J.
Am. Chem. Soc. 1994, 116, 4221. (i) Palladium-catalyzed bis-silylation of
optically active allylic alcohols; Suginome, M.; Matsumoto, A.; Ito, Y. J. Am.
Chem. Soc. 1996, 118, 3061. (j) Substitution reactions of alkylmagnesium
reagents with optically active silyl-substituted allylic carbamates; Smitrovich,
J. H.; Woerpel, K. A. J. Org. Chem. 2000, 65, 1601.
(8) Synthesis of optically active cyclopropanes by intramolecular cyclization
of organolithium compounds, e.g.: (a) Krief, A.; Hobe, M. Tetrahedron Lett.
1992, 33, 6527 and 6529. (b) Hoppe, D.; Paetow, M.; Hintze, F. Angew. Chem.,
Int. Ed. Engl. 1993, 32, 394. (c) Norsikian, S.; Marek, I.; Klein, S.; Poisson,
J. F.; Normant, J. F. Chem. Eur. J. 1999, 5, 2055.
(9) Other methods for synthesis of optically active cyclopropanes, e.g., for
a general review: (a) Salau¨n, J. Chem. ReV. 1989, 89, 1247. Asymmetric
variants of Simmons-Smith reaction: (b) Charette, A. B.; Marcoux, J.-F.
Synlett 1995, 1197 and references therein. (c) Denmark, S. E.; O’Connor, S.
P. J. Org. Chem. 1997, 62, 584. Transition metal-catalyzed asymmetric
cyclopropanation of olefins with diazoacetates: (d) Pfaltz, A. Acc. Chem. Res.
1993, 26, 339 and references therein. (e) Park, S.-B.; Sakata, N.; Nishiyama,
H. Chem. Eur. J. 1996, 2, 303.
rangement, the silicon analogues to the [2,3]-Wittig rearrange-
ment,5 that is, the [(allyloxy)silyl]lithium bearing an alkyl group
on the terminus of the olefin undergoes the [2,3]-rearrangement
to afford the (E)-allylsilanes. The other is the cyclopropanation
reaction in which the [(allyloxy)silyl]lithium bearing a phenyl
group on the terminus of the olefin gives the corresponding
substituted cyclopropylsilane as a single diastereoisomer.6 We now
disclose the chirality transfer of these reactions using enantio-
enriched sec-allylic alcohol derivatives; the center of chirality at
one allylic carbon atom is intramolecularly transferred to the
newly formed stereogenic centers, which leads to optically active
allylsilanes7 and cyclopropylsilane.8,9
We first investigated the 1,3-chirality transfer during the [2,3]-
sila-Wittig rearrangement, as shown in Scheme 1. Treatment of
the [(sec-allyloxy)dimesitylsilyl]stannane10 (S)-(E)-1 (98% ee)
with n-BuLi (2.0 mol amt.) in THF at 0 °C for 3 h provided the
(1) For reviews of [2,3]-Wittig rearrangement: (a) Nakai, T.; Mikami, K.
Org. React. 1994, 46, 105. Asymmetric variants, e.g.: (b) Mikami, K.;
Fujimoto, K.; Kasuga, T.; Nakai, T. Tetrahedron Lett. 1984, 25, 6011. (c)
Marshall, J. A.; Wang, X. J. Org. Chem. 1992, 57, 2747. (d) Enders, D.;
Backhaus, D.; Runsink, J. Angew. Chem., Int. Ed. Engl. 1994, 33, 2098. (e)
Manabe, S. Chem. Commun. 1997, 737.
(2) Intramolecular carbolithiation, e.g.: (a) Coldham, I.; Hufton, R.;
Snowden, D. J. J. Am. Chem. Soc. 1996, 118, 5322. (b) Woltering, M. J.;
Fro¨hlich, R.; Hoppe, D. Angew. Chem., Int. Ed. Engl. 1997, 36, 1764. (c)
Hoppe, D.; Woltering, M. J.; Oestreich, M.; Fro¨hlich, R. HelV. Chim. Acta
1999, 82, 1860. (d) Tomooka, K.; Komine, N.; Sasaki, T.; Shimizu, H.; Nakai,
T. Tetrahedron Lett. 1998, 39, 9715. (e) Cheng, D.; Knox, K. R.; Cohen, T.
J. Am. Chem. Soc. 2000, 122, 412.
(3) For reviews of silyl anions: (a) Tamao, K.; Kawachi, A. AdV.
Organomet. Chem. 1995, 38, 1. (b) Lickiss, P. D.; Smith, C. M. Coord. Chem.
ReV. 1995, 145, 75. (c) Belzner, J.; Dehnert, U. In The Chemistry of Organic
Silicon Compounds; Rappoport, Z., Apeloig, Y., Eds.; John-Wiley & Sons:
Chichester, 1998; Vol. 2, pp 779-826.
(4) The term “sec-allylic” means that the allylic carbon is secondary.
(5) Kawachi, A.; Doi, N.; Tamao, K. J. Am. Chem. Soc. 1997, 119, 233.
(6) Kawachi, A.; Maeda, H.; Tamao, K. Chem Lett. 2000, 1216.
(10) The [(allyloxy)dimesitylsilyl]stannanes were prepared by the reaction
of the corresponding enantio-enriched sec-allylic alcohols and the chloro-
(dimesityl)silylstannane in THF in the presence of triethylamine and 4-(di-
methylamino)pyridine; see ref 5. The optically active allylic alcohols were
derived from commercially available (S)-(-)-3-butyn-2-ol (98% ee); see
Supporting Information.
(11) The enantiomeric excess of 2 was directly determined by chiral HPLC
analysis using CHIRALPAK AD column eluted with hexane/2-propanol (50/
1). The absolute configuration of the allylsilanes was determined after
conversion to the allylic alcohols by m-chloroperbenzoic acid according to
the literature; Hayashi, T.; Okamoto, Y.; Kabeta, K.; Hagihara, T.; Kumada,
M. J. Org. Chem. 1984, 49, 4224, and see ref 7i.
(12) For transition state structures of the [2,3]-Wittig rearrangement: (a)
Wu, Y.-D.; Houk, K. N.; Marshall, J. A. J. Org. Chem. 1990, 55, 1421. (b)
Mikami, K.; Uchida, T.; Hirano, T.; Wu, Y.-D.; Houk, K. N. Tetrahedron
1994, 50, 5917. (c) Okajima, T.; Fukazawa, Y. Chem. Lett. 1997, 81.
10.1021/ja003749i CCC: $20.00 © 2001 American Chemical Society
Published on Web 03/08/2001

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3144 J. Am. Chem. Soc., Vol. 123, No. 13, 2001
Scheme 2
Communications to the Editor
Scheme 5
Scheme 3a
whereas 8b results from (S)-(Z)-4 via (S)-(Z)-7. The epimers 8a
and 8b are expected to be configurationally labile at the benzylic
center and are in equilibrium.2b,c Subsequently, cyclopropanation
of the oxasilacyclobutanes 8a and 8b takes place from a
conformation, avoiding steric strain between the phenyl residue
and the mesityl group(s), with inversion at the C-O bond. For
the formation of (1R,2S,3S)-5 from 8a, inversion of the benzylic
center is required, whereas starting from 8b, retention leads to
the observed stereochemistry.14
In conclusion, we have achieved the chirality transfer in the
[2,3]-sila-Wittig rearrangement and the cyclopropanation reaction
of the chiral [(sec-allyloxy)silyl]lithiums. While the former
reaction allows the stereoselective formation of one Si-C bond,
the latter reaction allows the stereoselective formation of one C-C
bond in addition to one Si-C bond and can define the absolute
configurations of three stereocenters in the cyclopropane ring.
Since a variety of optically active allylic alcohols are now
available by established methods,15,16 the present method will
widen its variation. The scope and limitations are now under
investigation.
a (a) n-BuLi (×1.2), THF, 0 °C, 3 h. (b) 5% NH4Cl aq.
Scheme 4
We next applied this chirality transfer technique to the
cyclopropanation reaction, the other reaction mode of the [(sec-
allyloxy)silyl]lithiums,6 in which the sense of chirality at the allylic
position in the substrate would define the absolute configuration
of three stereocenters in the resulting cyclopropane. The results
are shown in Scheme 3. Thus, treatment of the enantio-enriched
(S)-(E)-4 (98% ee)10 with n-BuLi (1.2 mol amt.) in THF at 0 °C
for 3 h afforded (1R,2S,3S)-5 in 79% yield with 98% ee.13 Under
the same reaction conditions, (S)-(Z)-4 (98% ee) gave the same
stereoisomer (1R,2S,3S)-5 in 71% yield with 98% ee. The absolute
configuration (1R,2S,3S) of 5 was definitely determined by the
X-ray crystallographic analysis of the ester 6 obtained by treatment
with (R)-R-methoxy-R-(trifluoromethyl)phenylacetyl chloride, as
shown in Scheme 4. Thus, the resulting stereochemistry depends
on the absolute configuration of the allylic carbon independent
of the olefin geometry in 4, in sharp contrast to the [2,3]-sila-
Wittig rearrangement mentioned above.
Acknowledgment. We thank the Ministry of Education, Science, and
Culture, Japan, for Grants-in-Aid for Scientific Research (Nos. 12042241
and 12750763). H.M. and H.N. thank the Japan Society for the Promotion
of Science (fellowship for Japanese Junior Scientists). We are grateful
to Dr. Michinori Suginome and Professor Yoshihiko Ito for their
instruction of the determination of the absolute configuration of the
allylsilanes.
Supporting Information Available: Experimental details and X-ray
structural information of 6 (PDF). An X-ray crystallographic file (CIF).
This material is available free of charge via the Internet at http://pubs.acs.org.
JA003749I
(14) For stereochemistry at the lithiated carbon for the reaction of the
organolithium compounds with electrophiles: Gawley, R. E.; Low, E.; Zhang,
Q.; Harris, R. J. Am. Chem. Soc. 2000, 122, 3344 and references therein.
(15) (a) Martin, V. S.; Woodard, S. S.; Katsuki, T.; Yamada, Y.; Ikeda,
M.; Sharpless, K. B.; J. Am. Chem. Soc. 1981, 103, 6237. (b) Gao, Y.; Hanson,
R. M.; Klunder, J. M.; Ko, S. Y.; Masamune, H.; Sharpless, K. B. J. Am.
Chem. Soc. 1987, 109, 5765.
(16) Synthesis of optically active propargylic alcohols, e.g.: (a) Matsumura,
K.; Hashiguchi, S.; Ikariya, T.; Noyori, R. J. Am. Chem. Soc. 1997, 119, 8738.
(b) Tan, L.; Chen, C.-y.; Tillyer, R. D.; Grabowski, E. J. J.; Reider, P. J.
Angew. Chem., Int. Ed. 1999, 38, 711. (c) Zhen, L.; Upadhyay, V.; DeCamp,
A. E.; DiMichele, L.; Reider, P. J. Synthesis 1999, 1453. (d) Frantz, D. E.;
Fa¨ssler, R.; Carreira, E. M. J. Am. Chem. Soc. 2000, 122, 1806.
The stereochemical course is rationalized as follows.6 An
intramolecular syn-lithiosilylation via 7 proceeds in the initial step,
facilitated by the stabilizing phenyl residue, as shown in Scheme
5. The intermediate 8a is formed from (S)-(E)-4 via (S)-(E)-7,
(13) The enantiomeric excess of 5 was directly determined by chiral HPLC
analysis using CHIRALCEL OD column eluted with hexane/2-propanol (100/
1.5).