Asymmetric aerobic oxidative NHC-catalysed synthesis of dihydropyranones utilising a system of electron transfer mediators.

A Axelsson,E Hammarvid,H Sundén,L Ta

doi:10.1039/c6cc06060a

Abstract

In the context of green chemistry, the replacement of high molecular weight stoichiometric oxidants with O2 is most desirable but difficult. Here, we report the asymmetric aerobic oxidative synthesis of dihydropyranones. The oxidation is aided by a system of electron transfer mediators and is selective toward the homoenolate. The dihydropyranones can be isolated in high to excellent yields, with high ee (up to 95%).

Highlights

In the context of green chemistry, the replacement of high molecular weight stoichiometric oxidants with O2 is most desirable but difficult
Asymmetric aerobic oxidative N-heterocyclic carbene (NHC)-catalysed synthesis of dihydropyranones utilising a system of electron transfer mediators†
Within the field of asymmetric N-heterocyclic carbene (NHC) catalysis,[1,2,3,4,5,6,7,8] oxidative reaction paths have emerged as an attractive way to activate a,b-unsaturated aldehydes towards nucleophiles.[9,10,11]

Summary

Introduction

In the context of green chemistry, the replacement of high molecular weight stoichiometric oxidants with O2 is most desirable but difficult. Asymmetric aerobic oxidative NHC-catalysed synthesis of dihydropyranones utilising a system of electron transfer mediators† We report the asymmetric aerobic oxidative synthesis of dihydropyranones.

Results

Conclusion