3-Methyl-3-sulfolene, in Diels-Alder

W-Methylpiperidine, 52, 127 3-Methyl-3-sulfolene, in Diels-Alder reaction, 50, 48 MODIFIED CLEMMENSEN REDUCTION CHOLESTANE, 53, 86... 

A report of Backer and Blaas6 is responsible for evolution of the present procedure these workers were first to conduct a Diels-Alder synthesis utilizing a 3-sulfolene in place of the free diene (by heating the cyclic adduct of sulfur dioxide and 2-methyl-3-thiomethyl-1,3-butadiene with maleic anhydride). The generality of the method as a variant of the conventional diene synthesis is limited largely by the availability of the appropriate 3-sulfolene its greatest utility, perhaps, will be presently realized in those diene reactions normally requiring 1,3-butadiene, since 3-sulfolene itself is now the least expensive and most widely available diene cyclic sulfone. 

In our laboratories, problems have been encountered in predicting the stereoselectivity of intramolecular Diels-Alder reactions from 2,3-disubstituted sulfolenes bearing a methyl ester or dimethylamide in the 3-position, intermediate dienes of differing geometries perhaps being responsible [70,72,75]. Model sulfolenes we therefore constructed to find out the effect of changing substituents... 

---