The 2 structures of la and its azido analogue 2a are established by the coupling constants of the olefinic protons (J= 12 Hz). The 2 structures of lb and IC were assigned on the basis of their facile conversion to the quinolines 4b and 4c by boiling in ethanol. Conversely, the isomers 5b and 5c (see Chart 11) were unchanged in boiling ethanol, indicating E structures, although 5b, like 5a, 1 could be converted to the quinoline by treatment with ...