Facile Synthesis of Oleanane-type Pentacyclic Triterpenoids Bearing Hydroxy Groups on D/E Rings

Abstract

Pentacyclic triterpenoids (PTs) comprise one of the largest class of natural products; many bear higher oxidation state on the D/E rings and exhibit a wide range of biological activities. Here, we report the chemical synthesis of a series of oleanane-type PTs bearing hydroxy groups on D/E rings from the largely available oleanolic acid by transformations following site-selective C−H hydroxylation.