Asymmetric routes in the reaction of cyclic ketene ortho ester with aldehydes involving the use of chiral Lewis acid
作者:Chan-Mo Yu、Jae-Young Lee、Kwangwoo Chun、In-Kyung Choi、Suk-Ku Kang
DOI:10.1039/b107454g
日期:2001.12.19
Enantio- and diastereoselective synthesis of threo 2 and erythro 3 was accomplished by the conversion of 1 with aldehydes promoted by chiral borane 10; enantioselctivities range from 45–95% ee, while diastereoselectivities vary from 4.3–49∶1 with 8 different aldehydes.
Regulation of diastereoselectivity through the epimerisation of a cyclic intermediate in the reaction of cyclic ketene ortho ester with aldehydes
作者:Chan-Mo Yu、Jae-Young Lee、Kwangwoo Chun、Junhee Lee、Yong-Am Lee
DOI:10.1039/b005086p
日期:——
A highly stereocontrolledsynthesis of 3 was accomplished. This involves the conversion of the cyclic intermediate 5 (from the reaction of dihydropyran 1 with aldehyde promoted by Lewis acid catalyst) to 6 in the presence of bases and introduction of an ester functionality from hydrolysis of the ortho ester intermediate. The method described herein is successful with a variety of aldehydes and affords