A semi-synthetic route to the D-ring analogs of (–)-epigallocatechin gallate (EGCG) from the relatively abundant (–)-epigallocatechin (EGC), isolated from green tea leaves, is described. A natural product (13), found in Cistus salvifolius, its acetate (14) and analog (17) were synthesized by this method. Their inhibitory activities against proteasomes were investigated.Key words: green tea, (–)-epigallocatechin gallate (EGCG), (–)-epigallocatechin (EGC), proteasome inhibition.