However, the use of chiral auxiliary unsaturated ester or amide with stabilised sulfur ylide is limited. So far few methods has been reported, such as using pyroglutamic acid (O,N-acetal and N-Boc-pyrrolinone) as a chiral auxiliary  unsaturated amide with stabilized sulfur ylide. However the Diastereoselectivity is very poor. Still there are demands for better Diastereoselectivity methods. Therefore, development of new methods for stereoselective cyclopropanation of the unsaturated ester or amide which bear an appropriate chiral auxiliary continues to be an important area of research.