Synthesis of 1-Substituted Derivatives of 2,5-Diphenylsilacyclopent-3-enes and 2,5-Diphenylsilacyclopentanes

Yukinori NAGAO*, Shinichi SAKAMOTO, Kenichi MIYAKAWA, Yoshimoto ABE and Michael E. JUNG†

Department of Industrial Chemistry, Faculty of Science and Technology, Science University of Tokyo, Noda-shi 278-8510 Japan
† Department of Chemistry and Biochemistry, University of California; Los Angeles, CA 90024, U.S.A.

Synthesis of 1,1-disubstituted derivatives of 2,5-diphenylsilacyclopent-3-enes and 2,5-diphenylsilacyclopentanes was investigated.
1,1-Disubstituted derivatives of 2,5-diphenylsilacyclopent-3-enes having dialkoxy, 1-alkoxy-1-methyl, 1-alkoxy-1-chloro, and 1-alkyl-1-chloro were prepared by one-pot reaction of (1E, 3E)-1,4-diphenylbuta-1,3-diene and dichlorosilanes in the presence of magnesium. 1,1-Dialkoxy derivatives were obtained in about 80% yield, but 1-alkyl-1-chloro derivatives were obtained under 50% yield. Each silacyclopentenes was given as the mixture of trans and two cis isomers. 1,1-Dialkoxy derivatives were obtained as a trans rich form and 1-alkyl-1-chloro derivatives were obtained as only cis isomer. Then the hydrogenation of 1,1-disubstituted derivatives of 2,5-diphenylsilacyclopent-3-enes by hydrogen gas in the presence of Pd-C gave the corresponding derivatives of 2,5-diphenylsilacyclopentanes.


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