Synthesis of Tertiary α-Hydroxy Acids by Silylene Transfer to α-Keto Esters
摘要:
alpha-Keto esters can be converted into alpha-hydroxy acids in a single flask involving metal-catalyzed silylene transfer, 6 pi-electrocyclization, Ireland-Claisen rearrangement, and hydrolysis. This reaction sequence is stereoselective and tolerates alkyl- and aryl-substituted a-keto ester substrates as well as an alpha-imino ester.
undergoes facile thermal cyclisation affording nitrones 1c and 1d in good yield. Oximes E-5a,b with a terminal methyl substituent on the alkene moiety furnish nitrone only under the influence of an external electrophile [PhSeBr/AgBF4]. A terminal Ph substituent on 5c,d prohibits formation of the cyclic dipole irrespective of reaction conditions, and whilst 5d reacts to afford a bicyclic isoxazolofuranone
Synthesis of Tertiary α-Hydroxy Acids by Silylene Transfer to α-Keto Esters
作者:Brett E. Howard、K. A. Woerpel
DOI:10.1021/ol702148x
日期:2007.10.1
alpha-Keto esters can be converted into alpha-hydroxy acids in a single flask involving metal-catalyzed silylene transfer, 6 pi-electrocyclization, Ireland-Claisen rearrangement, and hydrolysis. This reaction sequence is stereoselective and tolerates alkyl- and aryl-substituted a-keto ester substrates as well as an alpha-imino ester.