Synthesis of 2H-naphtho[2,3-b]thiopyranoquinones and density functional study for the Diels-Alder reaction of a benzothiopyranoquinone

The synthesis of benzothiopyranoquinone (6) in three step from benzothiopyr an (3) is described. Diels-Alder reaction of quinone (6) with 1,3-pentadien e (7), cyclopentadiene, 1-methoxy-1,3-cyclohexadiene (11) and 1-dimethylami no-1-aza-1,3-pentadiene (14) was studied. The Density Functional Theory was applied to explain the orientation of the cycloaddition reaction of quinon e (6) with dienes (7), (11) and (14).