The chemistry of santonene. Part III. Some autoxidation products

Abstract

Autoxidation of santonene (6-hydroxyeudesma-1,5,7(11)-trien-3-one-13-oic acid 6 → 13-lactone) affords 4β-, 4α-, and 6β-hydroxysantonenes, and the 6-hydroxy-13-noreudesma-1,4,6-trien-3,11-dione (IV). The 4α- and 4β-hydroxysantonenes afford 1,2-dihydro-derivatives, and also acetates. Catalytic hydrogenation of the 4β-acetate leads to hydrogenolysis of the acetoxyl group. Acetylation of 1,2-dihydro-4β-hydroxysantonene affords 2β-acetoxy-3-O-acetyl-1,2-dihydrosantonene (X). The 4α-hydroxy-santonene shows normal reactions. Acetylation of the 6β-hydroxysantonene affords 6α-, 6β- and 11-acetates. The rearrangement of these acetates under acidic conditions is described.