INTRAMOLECULAR DIELS-ALDER REACTIONS - CONSTRUCTION OF AZA-STEROID AND DIAZA-STEROID TYPE SKELETONS

The preparation of 2-(4-phenyl)butadienyl-pipcridine 5 is described. An intramolecular Diels-Alder reaction of the intermediately formed fumaramide thereof produces sterooselectively the tricyclic lactam 6. Its structure, as well as the configurational relationship of its 5 asymmetric centers, is corroborated on the basis of the NMR.-data. Cycloacylation of the thermodynamically stable precursors 13 and 20 leads to pentacyclic aza- or diaza-steroid type skeletons. Their structures (14,16 and 21) and in particular their relative configurations arc elaborated. A few qualitative kinetic aspects of this intramolecular (4 + 2)-cycloaddition are presented.