Synthesis of some tetrahydrosantonin derivatives with functionalised angular substituents based on remote oxidation

Abstract

On treatment with lithium di-isopropylamide, the tosylhydrazone (3b) of tetrahydrosantonin (3a) provided the olefin (4) regioselectively, from which the bromohydrin (5) was obtained by the addition of hypobromous acid. Photochemical remote oxidation of (5) was executed in the presence of lead tetraacetate and iodine to give the bromo dilactone (8) as the major product. Tetrahydrosantonin derivatives with functionalised angular substituents (10)–(18) were efficiently derived from (8).