Asymmetric vicinal acylation of olefins: A new approach to enantiomerically pure γ-lactones.
作者:Christophe Genicot、Léon Ghosez
DOI:10.1016/s0040-4039(00)60187-9
日期:1992.11
Amide 3 derived from N-tosylsarcosine and (2R,5R)-dimethylpyrrolidine was converted into keteniminium salt 4 which readily cycloadded to olefins. Hydrolysis of the adducts yielded cyclobutanones which were regiospecifically oxidized to gamma-lactones 7. High enantioselectivities were observed with 1,2-cis-disubstitued olefins.
A two-step sequence for the asymmetric vicinal acylation of olefins by a [2+2+1] strategy is reported. The key reaction is a [2+2] cycloaddition of an olefin to a chiral keteniminium salt derived from N-tosylsarcosinamide. This is followed by a regioselective Baeyer-Villigeroxidation of the resulting cyclobutanone to yield a lactol derivative that is equivalent to the product of addition of a carboxyl