89385-19-3Relevant articles and documents
Procyanidin oligomers. A new method for 4→8 interflavan bond formation using C8-boronic acids and iterative oligomer synthesis through a boron-protection strategy
Dennis, Eric G.,Jeffery, David W.,Johnston, Martin R.,Perkins, Michael V.,Smith, Paul A.
experimental part, p. 340 - 348 (2012/01/06)
Interest in the synthesis of procyanidin (catechin or epicatechin) oligomers that contain the 4→8 interflavan linkage remains high, principally due to research into their health effects. A novel coupling utilising a C8-boronic acid as a directing group was developed in the synthesis of natural procyanidin B3 (i.e., 3,4-trans-(+)-catechin-4α→8-(+)- catechin dimer). The key interflavan bond was forged using a novel Lewis acid-promoted coupling of C4-ether 6 with C8-boronic acid 16 to provide the α-linked dimer with high diastereoselectivity. Through the use of a boron protecting group, the new coupling procedure was extended to the synthesis of a protected procyanidin trimer analogous to natural procyanidin C2.
