Development of the silyl-zincation of allenes

ORGN 175

Mitsuhiro Yonehara, ff56038@mail.ecc.u-tokyo.ac.jp, Shinji Nakamura, and Masanobu Uchiyama, uchiyama@mol.f.u-tokyo.ac.jp. Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
Allyl- and vinylsilanes are among the most important intermediates in organic chemistry. Recently, we have reported the regio- and chemoselective silyl-zincation of terminal alkenes and alkynes using newly developed dianion-type zincates. In this presentation, we would like to report the silyl-zincation of 1-substituted allenes, which have the potential for the synthesis of allyl- and vinylsilanes. Our initial studies using 1-phenylallene (1) as a model substrate, aimed at identifying favorable reaction conditions, revealed that a dimethylphenylsilyl (DMPS) group as the silyl moiety and THF as a solvent were suitable starting points for optimization of the silyl-zincation reaction conditions. After extensive experimentation, we found two effective reagents, DMPS-Zn-Me and (DMPS)3ZnLi that reacted 1 smoothly at room temperature without any transition metal catalysts to give branched and linear vinylsilanes, respectively.