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Copper-catalyzed regioselective trans-silaboration of internal arylalkynes with stereochemical switch to cis-addition
Toshimichi Ohmura1, Yuta Takaoka1, Michinori Suginome1
1Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura Nishikyo-ku Kyoto 615-8510, Japan. ohmura@sbchem.kyoto-u.ac.jp suginome@sbchem.kyoto-u.ac.jp.
Abstract:
Copper-catalyzed silafunctionalization of alkynes using a silylboronic ester as a silicon source has recently progressed rapidly. Generally, the reaction affords a product with cis-stereoselectivity. We herein describe trans-selective 1,2-addition of silylboronic esters to internal arylalkynes, which was promoted efficiently by the CuOt-Bu/RCy2P/NaOt-Bu catalysts. Moreover, we report a stereochemical switch to cis-addition in the reactions of Me2(i-PrO)Si-B(pin) in hydrocarbon solvents including cyclohexane.
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