First Total Synthesis of Piperenol B and Configuration Revision of the Enantiomers Piperenol B and Uvarirufol A

Abstract

AbstractWe report herein the first total synthesis of piperenol B, a polyoxygenated cyclohexene derivative with reported pharmacological activity isolated from Piper cubeb. The chiral building block for this synthetic approach is derived from microbial cis‐ipso,ortho‐dihydroxylation of sodium benzoate, which was optimized to the multi‐ten‐gram scale by reaction medium engineering. Final‐stage deprotection of an acetonide was investigated in detail, leading to an efficient eight‐step protocol for the synthesis of piperenol B with a total yield of 10 %. Most importantly, the previously assigned absolute configuration of piperenol B was revised and unequivocally established by 2D NMR analysis and the Mosher's ester method.