An enantioselective synthesis of biologically important imidazolidines has been achieved via a tandem [3 + 2] cycloaddition/1,4-addition reaction of azomethine ylide and aza-o-quinone methides. With the use of this tool, various imidazolidinederivatives are obtained in good yields with excellent diastereoselectivities and enantioselectivities.
Diversity Oriented Synthesis of Pyrrolidines via Natural Carbohydrate Solid Acid Catalyst
作者:Atul Kumar、Garima Gupta、Suman Srivastava
DOI:10.1021/cc100007a
日期:2010.7.12
carbohydrate scaffold catalyzed diastereoselective synthesis of functionalized pyrrolidines have been developed via 1,3-dipolarcycloaddition of azomethine ylides derived from α-imino esters with dienes or dipolarophiles. Naturally most abundant carbohydrates, like cellulose and starch, were converted into their sulfuric acid derivative, which are exhibiting efficient catalytic properties, along with excellent
The first metal-catalyzed [6 + 3] cycloaddition of tropone with azomethine ylides has been developed. With the use of a chiral ferrocenylphosphine-copper(I) complex as the catalyst, the asymmetric variant of the [6 + 3] cycloaddition has also been successfully achieved. The reactions proceeded smoothly under mild conditions, affording piperidine-fused bicyclic heterocycles in moderate to high yields with good to excellent diastereo- and enantioselectivies. The procedures are operationally simple and the catalysts are cheap and readily accessible, thus providing a practical approach to piperidine-fused bicyclic heterocycles.