Palladium-catalyzed asymmetric silaboration of allenes
Palladium-catalyzed asymmetric silaboration of allenes
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DOI：
10.1021/ja063934h
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发表时间：
2006-10-25
影响因子：
15
通讯作者：
Suginome, Michinori
中科院分区：
文献类型：
--
作者：
Ohmura, Toshimichi;Taniguchi, Hiroki;Suginome, Michinori
An enantioselective silaboration of allenes was achieved using an achiral silylborane in the presence of a palladium catalyst bearing a chiral monodentate phosphine ligand. (R)-2-Bis(3,5-dimethylphenyl)phosphino-1,1‘-binaphthyl gave the highest enantioselectivities in the addition of (diphenylmethylsilyl)pinacolborane to the internal CC bond of terminal allenes at 0 °C, giving the corresponding β-borylallylsilanes in high yields with high enantiomeric excesses. The enantioselectivity depended on the bulkiness of substituents of allenes: the enantiomeric excesses were found to be 91−93% ee (R =tert- andsec-alkyl), 88−90% ee (R = aryl), and 80−82% ee (R =prim-alkyl and Me) at 0 °C. Perfect chirality transfer was observed in the intramolecular cyclization reactions of the functionalized allylsilanes, affording highly enantioenriched cyclic alkenylboranes, which underwent Suzuki−Miyaura coupling with aryl halides.
