Palladium-catalyzed asymmetric silaborative C-C cleavage of meso-methylenecyclopropanes
Palladium-catalyzed asymmetric silaborative C-C cleavage of meso-methylenecyclopropanes
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DOI：
10.1021/ja0703170
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发表时间：
2007-03-28
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 silaborative C-C cleavage of meso-methylenecyclopropanes (meso-MCPs) was achieved by using a palladium catalyst bearing a chiral monodentate phosphine ligand. The (R)-2-bis(3,5-dimethylphenyl)phosphino-1,1'-binaphthyl gave the highest enantioselectivity in the reactions with (methyldiphenylsilyl)pinacolborane at 50 degrees C, affording derivatives of 2-boryl-4-silyl-1-butene in high yields with high enantiomeric excesses. The reactions of bicyclic MCPs that have fused five- to eight-membered rings gave the corresponding products with 89-91% ee, whereas a little lower ee was observed in the reaction of a non-fused MCP (81% ee). Synthetic applications of the products were demonstrated through synthesis of beta-silyl ketones by H2O2 oxidation and synthesis of stereodefined homoallylic alcohols via homologation-allylboration sequence, in which the chiral beta-substituent of the allylborane has critical impact on the diastereochemical outcome.
