Synthesis of β-Substituted α-Amino Acids via Lewis Acid Promoted Radical Conjugate Additions to α,β-Unsaturated α-Nitro Esters and Amides
作者:G. S. C. Srikanth、Steven L. Castle
DOI:10.1021/ol036461h
日期:2004.2.1
[reaction: see text] Beta-substituted alpha,beta-unsaturated alpha-nitro esters and amides undergo radical conjugate additions when treated with an appropriate Lewis acid. Deuterium studies revealed that the acidic alpha-stereocenter of the alpha-nitro ester products does not racemize under strictly controlled workup conditions. The alpha-nitro amides did racemize significantly during chromatography
Synthesis of β-Substituted α-Amino Acids via Lewis Acid Promoted Enantioselective Radical Conjugate Additions
作者:Liwen He、G. S. C. Srikanth、Steven L. Castle
DOI:10.1021/jo051334f
日期:2005.9.1
Lewisacid promoted radicalconjugateadditions to β-substituted α,β-unsaturated α-nitro esters and amides were investigated. With achiral Lewisacids, there was competition between the desired radicalconjugateaddition and undesired alkene reduction mediated by Bu3SnH. Zinc Lewisacids provided the greatest amounts of addition products with both substrate classes. Studies with Bu3SnD indicated that