Divergent Oxidation Reactions of E- and Z-Allylic Primary Alcohols by an Unspecific Peroxygenase

Abstract

Unspecific peroxygenases (UPOs) catalyze the selective oxygenation of organic substrates using only hydrogen peroxide as the external oxidant. The PaDa−I variant of the UPO from Agrocybe aegerita catalyses the oxidation of Z- and E-allylic alcohols with complementary selectivity, giving epoxide and carboxylic acid/aldehyde products respectively. Both reactions can be performed on preparative scale with isolated yields up to 80 %, and the epoxidations proceed with excellent enantioselectivity (>99 % ee). The divergent reactions can also be used to transform E/Z mixtures of allylic alcohols, enabling both product series to be isolated from a single reaction. The utility of the epoxidation method is exemplified in the total synthesis of both enantiomers of the insect pheromone disparlure, including a highly enantioselective gram-scale transformation. These reactions provide further evidence for the potential of UPOs as catalysts for the scalable preparation of important oxygenated intermediates.