SYNTHESIS OF TRANS-1,1-DIALKOXY-2,5-DIPHE NYL-1-SILA-3-CYCLOPENTENES AND THEIR 2-ALKYL DERIVATIVES

The reaction of 1,1-diethoxy or 1-diisopropoxy-2,5-diphenyl-1-sila-3-c yclopentene, containing cis and trans isomers, with LDA followed by th e reaction with alkyl bromides (alkyl=Et, n-Pr, i-Pr, i-Bu, s-Bu) and then acetic acid was investigated. The cis isomer of the 2,5-diphenyl- 1-sila-3-cyclopentene was selectively substituted by alkyl group to gi ve y-r-2-alkyl-2,t-5-diphenyl-1-sila-3-cyclopentenes. The trans isomer of 2,5-diphenyl-1-sila-3-cyclopentenes could be isolated by silica ge l chromatography from the reaction mixture.