REINVESTIGATION OF BIRCH REDUCTION OF BENZO[1,3]DIOXOLES AND FURTHER TRANSFORMATIONS OF THE RESULTING DIHYDRO COMPOUNDS

In spite of early reports by Birch, we demonstrated that treatment of benzodioxoles with sodium in ammonia in the presence of methanol almos t quantitatively yields the corresponding dihydro compounds. Despite t heir poor stability these compounds are synthetically useful. Treatmen t of 5-isobutyl-4,7-dihydrobenzo[1,3]dioxole with bromotrimethylsilane gives 6-hydroxy-3-isobutylcyclohex-2-enone in 80% yield. Treatment of 4,7-dihydrobenzo[1,3]dioxole with potassium in liquid ammonia in the presence of iron(III) chloride leads to 3a,4-dihydrobenzo[1,3]dioxole in high yield..