Enantioselective preparation of cis-β-azidocyclopropane esters by cyclopropanation of azido alkenes using a chiral dirhodium catalyst.

A diastereo- and enantiocontrolled preparation of the conformationally restricted cis-β-azidocyclopropane esters have been developed. The Rh(2)(S-DOSP)(4) was found to be an efficient catalyst in hexane for the cyclopropanation of azido alkenes with diazo esters, and 19 cis-β-azidocyclopropane esters were prepared in excellent yields. The value of the diastereomer ratio was up to 99:1, and the enantiomeric excess was up to 95%. Furthermore, the relative and absolute configuration was confirmed by X-ray analysis.