Ritter Reactions. VII. Diverse Reactivity of the 3-Azatricyclo[5.3.1.0^4,9]-undec-2-ene System With Dimethyl Acetylenedicarboxylate

Abstract

The imine functionality of the 3-azatricyclo[5.3.1.0^4,9]undec-2-ene derivatives (3a-c) reacts with dimethyl acetylenedicarboxylate to yield the lactam (5), the amino ester (6), and the oxopyrroline (7) respectively. Crystal structures of (6) [C₃₁H₃₄N₂O₅, Pca2₁, a 17.736(1), b 9.8412(4), c 15.584(1) Å , Z 4, R 0.032] and (7) [C₃₃H₃₆N₂O₆, Pca2₁, a 14.0610(8), b 9.6602(6), c 20.818(1) Å , Z 4, R 0.038] were determined. These widely differing modes of reaction result from the nature of the imine C2 substituent present in the starting material(3). Tentative mechanistic explanations are presented.