Stereochemistry of Disilanylene-Containing Cyclic Compounds. Synthesis and Reactions of cis- and trans-3,4-Benzo-1,2-di(tert-butyl)-1,2-dimethyl-1,2- disilacyclobut-3-ene

Abstract

The reaction of cis- and trans-3,4-benzo-1,2-di(tert-butyl)-1,2-dimethyl-1,2-disilacyclobut-3-ene (1a and 1b) with chlorine gas in carbon tetrachloride proceeded stereospecifically to give meso- and rac-1,2-bis[(tert-butyl)chloromethylsilyl]benzene (2a and 2b, respectively). The condensation of 2a and 2b with lithium and sodium produced a mixture of cis- and trans-benzodisilacyclobutene 1a and 1b, respectively. The reaction of 1a and 1b with molecular oxygen proceeded with high stereospecificity to give the respective cis- and trans-4,5-benzo-2-oxa-1,3-disilacyclopent-4-ene. The palladium-catalyzed reactions of 1a and 1b with phenylacetylene, 1-hexyne, tert-butylacetylene, phenyl-1-propyne, and diphenylacetylene proceeded in a stereospecific fashion to give the corresponding 5,6-benzo-1,4-disilacyclohexa-2,5-diene derivatives. Similar reactions of 1a and 1b with trimethylsilylacetylene, dimethylphenylsilylacetylene, and mesitylacetylene gave stereospecifically the erythro- and threo-1,2-bis(silyl)benzene derivatives. The structure of trans-5,6-benzo-1,4-di(tert-butyl)-1,4-dimethyl-2-phenyl-1,4-disilacyclohexa-2,5-diene was determined by single-crystal X-ray crystallography.