Chemistry of 2-methoxy-2,5-cyclohexadienones. I. Photochemistry of 2-methoxy-4,4-dimethyl-2,5-cyclohexadienone.

Abstract

The title compound, 2-methoxy-4, 4-dimethyl-2, 5-cyclohexadienone (V), was prepared from 2-methoxy-4, 4-dimethyl-2-cyclohexenone (VIa). A methanolic solution of V was irradiated with a 200 W mercury lamp at -3°C to give 2, 2-dimethoxy-6, 6-dimethylbicyclo [3. 1. 0] hexan-3-one (X) and 6, 6-dimethoxy-5, 5-dimethyl-2-cyclohexenone (XI) in yields of 36.5 and 7.8%, respectively. On the other hand, a methanolic solution of V was irradiated in the presence of a catalytic amount of sulfuric acid to give only 2-methoxy-4-(1-methoxy-1-methylethyl)-2-cyclopentenone (XIII) in 35.4% yield. The behavior of V and VIa in the presence of a catalytic amount of acid is also described.