Di-isophorone and related compounds. Part 5. 2,7-Epoxydi-isophoranes: oxiran cleavage by perchloric acid

Abstract

Perchloric acid slowly converts 2,7-epoxy-1-hydroxydi-isophoran-3-one into 1,4-dihydroxydi-isophor-2(7)-en-3-one, the structure of which is in accord with its alternative formation from 2,7-epoxy-1-hydroxydi-isophorane-3,4-dione by reduction with zinc in dimethylformamide. The 1,4-dihydroxy-3-one yields monoketonic and diacyl derivatives, including two stereoisomeric 1,4-diacetates. Its hydrogenation produces di-isophor-2(7)-ene-1,4-diol, while zinc in acetic acid regenerates the parent 1-hydroxydi-isophor-2(7)-en-3-one. Reduction of the 1,4-dihydroxy-3-one with lithium aluminium hydride or sodium borohydride yields two of the possible four stereoisomeric di-isophor-2(7)-ene-1,3,4-triols.