公开(公告)号：US20030100775A1

公开(公告)日：2003-05-29

申请号：US10214830

申请日：2002-08-08

Applicant: Mars Incorporated

Inventor： Alan P. Kozikowski ,  Leo J. Romanczyk JR. ,  Werner Tuckmantel

IPC: C07D311/74

CPC classification number: C07D311/74 ,  C07D311/62 ,  Y02P20/55

Abstract: Oligomeric procyanidins containing 4null-linked epicatechin units are rare in nature and have hitherto not been accessible through stereoselective synthesis. Provided herein is the preparation of the prototypical dimer, epicatechin-4null,8-epicatechin, by reaction of the protected 4-ketones with aryllithium reagents derived by halogen/metal exchange from the aryl bromides. Removal of the 4-hydroxyl group from the resulting tertiary benzylic alcohols is effected by tri-n-butyltin hydride and trifluoroacetic acid in a completely stereoselective manner, resulting in hydride delivery exclusively from the null face.