The use of diazophosphonates in the synthesis of cyclic ethers

Abstract

Two routes to cyclic ethers based on diazophosphonates are described. The first involves the rhodium(II) catalysed O-H insertion of 2-propanol followed by Wadsworth-Emmons reaction to give the enol ethers 3, and deprotection and cyclisation to the cyclic enol ethers 5. The second route involves the preparation of aldehyde and ketone phosphonates 9, also by rhodium carbenoid O-H insertion reactions, followed by functional group interconversion. On treatment with sodium hydride the phosphanates 9 undergo intramolecular Wadsworth-Emmons reaction to give cyclic ethers 13.