Procyanidin C1
Procyanidin C1 is a B type proanthocyanidin. It is an epicatechin trimer found in grape.The stereoselective synthesis of seven benzylated proanthocyanidin trimers -epicatechin--epicatechin trimer, catechin--catechin--catechin trimer, epicatechin--epicatechin--catechin trimer and epicatechin--catechin- can be achieved with TMSOTf-catalyzed condensation reaction, in excellent yields. The structure of benzylated procyanidin C2 was confirmed by comparing the 1H NMR spectra of protected procyanidin C2 that was synthesized by two different condensation approaches. Finally, deprotection of -catechin and -epicatechin trimers derivatives gives four natural procyanidin trimers in good yields.
