A novel approach to chiral amino-cyclopropanes via cyclopropanations of enamides and allenamides.

摘要

Optically enriched chiral amino- and amido-cyclopropanes are very interesting building blocks due to their structural and biological activities. However, preparation of chiral amino-cyclopropanes via cyclopropanation of chiral enamides, which should be an efficient route, has received very little attention. Similar situation is also faced by the preparation of chiral amino-spiropentanes via direct cyclopropanation of allenamides. Recent developments in powerful metal catalyzed C-N bond formation methodology, together with our group's systematical research on stereoselective cyclization reactions based on chiral enamides and allenamides, bring this dissertation the opportunity to explore straightforward cyclopropanations of enamides and allenamides to prepare chiral amido-cyclopropanes and amido-spiropantanes, respectively. This dissertation is divided into three studies, which are: (1) Stereoselective Simmons-Smith cyclopropanation of chiral enamides and its application to the preparation of chiral amino-cyclopropanes; (2) Cyclopropanation of chiral enamides via Rhodium(II) catalyzed decomposition of alpha-diazo esters, which provides a method to stereoselectively construct highly functionalized amido-cyclopropanes. (3) Simmons-Smith cyclopropanation of allenamides, which represents the most straightforward method to prepare the structurally and biologically intriguing amido-spiropentanes.