Chemistry of the Podocarpaceae. LXI. The rearrangement of aryl phosphates to ortho-hydroxyaryl phosphonates

Abstract

Treatment of methyl 12-(diethoxyphosphoryloxy)podocarpa-8,11,13-trien-19-oate (14) or its 13-bromo derivative (7) with butyllithium effects a rearrangement of the phosphate group to give methyl 13-diethoxyphosphoryl-12-hydroxypodocarpa-8,11,13-trien-19-oate (11) in high yield. Similar treatment of some simple aryl phosphates indicates that the rearrangement is general. The reaction, which probably occurs by means of an ortho-metallation-nucleophilic displacement sequence, is superior to existing methods for the preparation of o-hydroxyaryl phosphonates.