Synthesis of 3,3-dimethoxy-2-aryl-2,3-dihydro-1-oxa-cyclopenta[l]phenanthren-2-ols and their conversion to 2(3H)- and 3(2H)-furanones

A number of new 3,3-dimethoxy-2-aryl-2,3-dihydro-1-oxacyclopenta[l]phenanthren-2-ols were synthesized by the base-catalyzed reaction between phenanthrenequinone and 4-substituted acetophenones in methanol. These furanols are unstable and are easily converted to stable 3-methoxy-3-aryl-3H-1-oxacyclopenta[l]phenathren-2-ones in excellent yields. The furanols are converted to 2-aryl-1-oxacyclopenta[l]phenanthren-3-ones on treatment with acids. Plausible mechanisms for some of these new transformations are proposed.