Synthesis of Unsymmetrical Biaryls from Arylsilacyclobutanes
摘要:
[GRAPHICS]Aryl(fluoro)silacyclobutanes and aryl(chloro)silacyclobutanes have been found to undergo cross-coupling reactions with aryl iodides. The rate of reaction and extent of homocoupling were dramatically affected by the addition of ligands for the palladium catalyst. With (t-Bu)(3)P a wide range of electronically and structurally diverse unsymmetrical biaryls have been prepared in good to excellent yields.
Palladium-Catalyzed Desymmetrization of Silacyclobutanes with Alkynes: Enantioselective Synthesis of Silicon-Stereogenic 1-Sila-2-cyclohexenes and Mechanistic Considerations
摘要:
A palladium-catalyzed enantioselective desymmetrization of silacyclobutanes with alkynes has been developed to give silicon-stereogenic 1-sila-2-cyclohexenes with high enantioselectivity. The products thus obtained undergo further derivatizations with complete stereoselectivity, and a new catalytic cycle involving alkyne coordination (oxidative cyclization)-transmetalation (sigma-bond metathesis)-reductive elimination has also been proposed.