Electrocyclization of β-arylvinyl ketenimines: Formal syntheses of the alkaloid from marine origin, 5,8-dihydro-7-methoxy-1,6-dimethylisoquinoline-5,8-dione, and 3-ethoxycarbonylrenierol

Article abstract of DOI:10.1055/s-1997-1277

A new six-step synthetic route for the preparation of the alkaloid from marine origin, 5,8-dihydro-7-methoxy-1,6-dimethylisoquinoline- 5,8-dione is reported. The method is based on the electrocyclization of the appropriate β-arylvinyl ketenimine, available by aza Wittig reaction of the corresponding vinyl iminophosphorane with (trimethylsilyl)ethenone followed by decarboxylation and further oxidative demethylation. Likewise, this method has successfully been applied to the preparation of the 3-ethoxycarbonylrenierol.