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 [2+2+1] strategy for the conversion of olefins into cyclopentenones. Ring expansion of 2-N-methyl-N-tosyl-cyclobutanones
作者:Florence Mahuteau-Betzer、Léon Ghosez
DOI:10.1016/s0040-4039(99)00948-x
日期:1999.7
alpha-N-Methyl-N-tosylcyclobutanones prepared by asymmetric cycloadditions of the corresponding keteniminium triflate to olefins have been converted into a mixture of epoxides using dimethylsulfonium ylide. Treatment of these epoxides with lithium iodide unexpectedly yielded the corresponding cyclopentenones. This sequence amounts to a [2+2+1] cyclopentannulation of an olefin. (C) 1999 Elsevier Science Ltd. All rights reserved.