Silylboranes bearing dialkylamino groups on silicon as silylene equivalents: Palladium-catalyzed regioselective synthesis of 2,4-disubstituted siloles

Article abstract of DOI:10.1021/ja073896h

Silylpinacolboranes bearing dialkylamino groups on the silicon atom served as synthetic equivalents of silylene in palladium-catalyzed reactions with terminal alkynes, leading to the formation of 2,4-disubstituted siloles in high yield. It was found that the amino group on the silicon atom was critically important for the reaction; no silole products were found in reactions using silylpinacolboranes carrying aryl, chloro, or alkoxy groups on the silicon atoms. Site-selective bromination of 1,1-dimethyl-2,4-diphenylsilole followed by Migita-Kosugi-Stille coupling with (arylalkynyl)tributylstannanes gave novel π-conjugated siloles with good total yields. Copyright