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Paper | Special issue | Vol 42, No. 1, 1996, pp.305-317
Published online, 1st January, 1970
DOI: 10.3987/COM-95-S35
Enantiopsecific Ring Expansion of Oxetanes: Stereoselective Synthesis of Tetrahydrofurans

Katsuji Ito, Miwa Yoshitake, and Tsutomu Katsuki

*Department of Chemistry, Faculty of Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan

Abstract

Enantiospecific ring expansion of oxetanes to tetrahydrofurans with diazoacetic acid ester was found to be catalyzed by the copper complex of (7R,7’R)-7,7’-di(1-tert-butyldimethylsiloxy-1-methylethyl)-6,6’,7,7’-tetrahydro-5H,5’H-2,2’-bi-1,1’-pyrindine (4). For example, the reaction of (R)-2-phenyloxetane of 89% ee and tert-butyl diazoacetate with Cu-4 complex as a catalyst provided (2S,3R)-tert-butyl 3-phenyltetrahydrofuran-2-carboxylate of 92% ee as a major product, while that of (S)-2-phenyloxetane of 85% ee provided (2S,3S)-tert-butyl 3-phenyltetrahydrofuran-2-carboxylate of 93% ee as a major one.