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Paper | Special issue | Vol 67, No. 2, 2006, pp.679-694
Published online, 18th November, 2005
DOI: 10.3987/COM-05-S(T)56
The Effect of Substituents on the Pyridine Ring in the Diastereoselective Cyclopropanation Reaction of Pyridinium Ylides Bearing an 8-Phenylmenthyl Ester Group

Satoshi Kojima,* Kouji Fujitomo, Yoshiaki Itoh, Kyoko Hiroike, Masaaki Murakami, and Katsuo Ohkata

*Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan

Abstract

The reaction between β-substituted methylidenemalononitriles and the ylide from (-)-8-phenylmenthyl α-pyridiniumacetate, which affords activated cyclopropanes bearing two cyano groups and one carboxylic ester group, was examined. The trans isomer was obtained in up to 91:9 diastereoselectivity under optimized solvent conditions for the t-butyl substituted substrate. The selectivity increased to 96:4 upon using 4-methoxypyridine in the place of pyridine, whereas selectivities were generally lower for N,N-diethylnicotinamide. The major 4-pyridyl substituted cyclopropane was determined to be trans-1R by X-Ray structural analysis.