ChemInform Abstract: Acid‐Induced Rearrangements of 2,8‐Diazabicyclo(3.2.1)octa‐3,6‐dienes Leading to 1,4‐Dihydropyridine and Pyrrole Derivatives.

Abstract

212ChemInform Abstract The 2,8-diazabicyclo(3.2.1)octadiene (Ia) is rearranged upon treatment with acids to give the pyrroles (IV) and (V), together with the dihydropyridine (III). A mixture of (III) -(V) is also obtained from the N-methoxycarbonylimine (VI). Silylation of (Ia) yields the N-pyrrolylvinyl O-silyl carbaminate (II). Reduction of the diester (Ia) produces the dimethyl derivative (Ib) which is converted tothe dihydropyridines (VII) or (VIII). The diazabicyclooctene (IX) forms the pyrrole (X) when heated in the presence of p-toluenesulfonic acid.