The conjugate addition of LSA 1 to t-butyl (4S)4-(trilyl)oxy-2-pentenoate 2d followed by aldol condensation with acetaldehyde produces a key intermediate 3 to beta-lactam derivatives as a single diastereoisomer in 77% yield.
Asymmetric synthesis of β-amino-γ-substituted-γ-butyrolactones: double diastereoselective conjugate addition of homochiral lithium amides to homochiral α,β-unsaturated esters
作者:Thaïs Cailleau、Jason W. B. Cooke、Stephen G. Davies、Kenneth B. Ling、Alan Naylor、Rebecca L. Nicholson、Paul D. Price、Paul M. Roberts、Angela J. Russell、Andrew D. Smith、James E. Thomson
DOI:10.1039/b712937h
日期:——
Chiral alpha,beta-unsaturated esters, containing a single, gamma-stereogenic centre, show modest levels of substrate control upon conjugate addition of lithium dibenzylamide. Double diastereoselective conjugate additions of homochiral lithium N-benzyl-N-(alpha-methylbenzyl)amide to the homochiral alpha,beta-unsaturated esters display "matching" and "mismatching" effects. In each case, however, these