The Claisen rearrangement approach to fused bicyclic medium-ring oxacycles

Abstract

The synthesis of five fused-bicyclic medium-ring lactones carrying identical ring-fusion to that in the polyether toxins is described using an enolate hydroxylation, intramolecular hydrosilation, Claisen rearrangement sequence.

Rhodium Carbenoid Initiated O–H Insertion/Aldol/Oxy-Cope Cascade for the Stereoselective Synthesis of Functionalized Oxacycles

“…In continuation of our interest in cascade reactions initiated by carbene O–H insertion, we now report a new approach involving β-hydroxy vinyl ketones and vinyl diazo esters for the synthesis of functionalized nine-membered oxacycles, which are important structural motifs found in many bioactive natural products . There have been several reports in literature for the synthesis of oxacycles through cyclization of an appropriate linear precursor (Figure a) .…”

Stereoselective Synthesis of Bicyclic Lactones Via Annelation Protocol

“…In particu lar, the γ-butyrolactone mo iety is a recurrent feature of many naturally occurring substances examp les are brasoside and littoralissone. 1,2 The synthetic approaches to th is b icyclic lactones have been imaginative and numerous, [3][4][5][6][7][8] there is a continued demand fo r efficien t methods fo r the assemb ling o f these key co mp o u n d s wh ich g iv e es p ec ia lly h ig h lev e ls o f stereoselectivity. In this report, it is reported some of our preliminary resu lts in the estab lish ment o f an effect ive met h odo logy fo r th e const ruct io n o f t hes e impo rtant compounds.…”