Methylation of 2-(2'-pyridyl) indole provides the corresponding N-methylated salt that undergoes deprotonation with mild base to provide the tautomeric (E)-1-methyl-2-(2'- indolenylidene)-1, 2-dihydropyridine, whose geometry is established through a NOE experiment. Bridging at the 3, 3'-positions leads to tautomers having the opposite stereochemistry. A benzo-fused analogue exhibits similar behavior as does 2-(2'- ...
