Platinum- and nickel-catalyzed reactions of 1,2-dimethyl-1,2-diphenyl-1,2-disilacyclopentane with alkynes

The platinum-catalyzed reactions of cis-1,2-dimethyl-1,2-diphenyl-1,2-disilacyclopentane (1a) with terminal acetylenes such as phenylacetylene and 1-hexyne in a degassed sealed tube at 150 °C for 24 h afforded cis-1,4-dimethyl-1,2,4-triphenyl-1,4-disilacyclohept-2-ene (2a) and cis-2-n-butyl-1,4-dimethyl-1,4-diphenyl-1,4-disilacyclohept-2-ene (3a), respectively, arising from insertion of a triple bond in the acetylenes into a siliconsilicon bond. Similar reactions of trans-1,2-dimethyl-1,2-diphenyl-1,2-disilacyclopentane (1b) with phenylacetylene and 1-hexyne gave trans-1,4-dimethyl-1,2,4-triphenyl-1,4-disilacyclohept-2-ene (2b) and trans-2-n-butyl-1,4-dimethyl-1,4-diphenyl-1,4-disilacyclohept-2-ene (3b), respectively. The platinum-catalyzed reactions of 1a and 1b with di-substituted acetylenes such as diphenylacetylene, 1-phenyl-1-propyne, and 3-hexyne gave the respective cis- and trans-1,4-dimethyl-1,4-diphenyl-1,4-disilacyclohept-2-ene derivatives with high stereospecificity. The nickel-catalyzed reactions of 1a and 1b with di-substituted acetylenes also proceeded with high stereospecificity to give the adducts as observed in the platinum-catalyzed reactions.