Transformation of fused bicyclic and tricyclic beta-lactones to fused gamma-lactones and 3(2H)-furanones via ring expansions and O-H insertions.
A two-step strategy for conversion of beta-lactones to gamma-lactones and 3(2H)-furanones was developed involving initial acyl C-O cleavage leading to delta-hydroxy-alpha-diazo-beta-ketoesters and beta-ketophosphonates. Subsequent tandem Wolff rearrangement/lactonization of these alpha-diazo intermediates provided cis-fused gamma-lactones efficiently under photolytic or thermolytic conditions. In addition, cis-fused 3(2H)-furanones were obtained by rhodium(II)-catalyzed O-H insertion reactions of the delta-hydroxy-alpha-diazo intermediates.
Zhang
Wei
W
Department of Chemistry, Texas A&M University, College Station, TX 77842-3012, USA.
Romo
Daniel
D