K2CO3-Promoted oxy-Michael Addition/Cyclization of α,β-Unsaturated Carbonyl Compounds with Naphthols: Synthesis of Naphthopyrans

Abstract

A potassium carbonate promoted tandem oxy-Michael addition/cyclization of α,β-unsaturated carbonyl compounds with naphthol derivatives for the synthesis of 2-substituted naphthopyrans was developed. Using the readily available, inexpensive potassium carbonate as the promoter, a range of different substituted naphthopyrans were prepared.

Total Synthesis of (+)-Peniciketal B

“…It was noteworthy that this key cascade process was accomplished under air at room temperature, which was an operationally simple protocol for the synthesis of the benzo-fused 2,8-dioxabicyclo[3.3.1]­nonane structure. Interestingly, a series of naphthopyrans were achieved when potassium carbonate was added as a reagent to the mixture of S6a and S8a , which was reported by our group recently …”