Diels-Alder Reactions of 12-Hydroxy-9(10？20)-5aH-abeo-abieta-1(10),8(9),12(13)-triene-11,14-dione

12-Hydroxy-9(10？20)-5aH-abeo-abieta-1(10),8(9),12(13)-triene-11,14-dione (quinone 2) served as the dienophile in numerous intermolecular Diels-Alder reactions. These cycloadditions were conducted either thermally (including microwave heating) or with Lewis acid activation. While most dienes reacted with quinone 2 in good chemical yield, others were incompatible under the experimental conditions used.