title: Diastereoselective tandem Michael-intramolecular Wittig reactions of a cyclic phosphonium ylide with 8-phenylmenthyl enoates.
abstract: The diastereoselective tandem Michael-intramolecular Wittig reactions of a five-membered cyclic phosphonium ylide 2 using 8-phenylmenthyl enoates were examined. The reaction of the phosphonium ylide with 8-phenylmenthyl cinnamate followed by the hydrolysis of the resulting enol ether 4a afforded (3R,4S)-4-(diphenylphosphinyl)-3-phenylcycloheptanone (3R,4S)-5a as the major isomer. The diastereoselectivity of the initial tandem reactions was estimated to be 94:6 from the 31P NMR of a mixture of the diastereomeric ketal derivatives 6a and 6'a which were obtained by the reaction of 5a with (2R,3R)-2,3-butanediol, and the absolute configuration of the major isomer was determined by the single-crystal X-ray analysis. Similar reactions using some 8-phenylmenthyl alkenoates were attempted. As a result, it was clarified that the corresponding trans-ketones 5b-d were obtained and that the diastereomer ratios of their ketal derivatives were 60:40-73:27.
authors: Department of Functional Polymer Science, Shinshu University, Tokida Ueda 386-8567, Japan.
authors: T
authors: T
authors: Nagao
authors: T
authors: T
authors: Suenaga
authors: T
authors: T
authors: Ichihashi
authors: T
authors: T
authors: Fujimoto
authors: I
authors: I
authors: Yamamoto
authors: A
authors: A
authors: Kakehi
authors: R
authors: R
authors: Iriye