Journal of the American Chemical Society, Vol.132, No.43, 15185-15191, 2010
Catalytic Asymmetric Synthesis of Chiral Allylic Esters
A broadly useful catalytic enantioselective synthesis of branched allylic esters from prochiral (Z)-2-alkene-1-ols has been developed. The starting allylic alcohol is converted to its trichloroacetimidate intermediate by reaction with trichloroacetonitrile, either in situ or in a separate step, and this intermediate undergoes clean enantioselective S(N)2 ' substitution with a variety of carboxylic acids in the presence of the palladium (II) catalyst (R-p,S)-di-mu-acetatobis[(eta(5)-2-(2 '-(4 '-methylethyl)oxazolinyl)cyclopentadienyl-1-C,3 '-N)(eta(4)-tetraphenylcyclobutadiene)cobalt]dipalladium, (Rp,S)-[COP-OAc](2,) or its enantiomer. The scope and limitations of this useful catalytic asymmetric allylic esterification are defined.