Unusual behaviour of thermally generated oxygen 1,3-diradicals from β-peroxylactones: stereoselective synthesis of a tetrahydrofuran ring by intramolecular hydrogen abstraction

Abstract

Thermolysis of the steroidal β-peroxylactone (3) gave ether (4), produced by Intramolecular hydrogen abstraction from a non-activated carbon; the reaction occurs with complete stereoselectivity by abstraction of the C₇-pro-R hydrogen, and a concerted mechanism is proposed, no free radicals seem to be involved in the reaction since when a true free radical hydrogen abstraction was realized with alcohol (7) no selectivity was observed and a mixture of ethers (4) and (8) was obtained.