Friedlander condensation of 0-aminoacrolein with a-oxo-2, 3-cycloalkenopyridines or thermolysis of the 0-allyloximes derived from these ketones leads to the formation of 3, 3'- bridged-2, 2'-bipyridines 2a-d. Reaction of 2a-d with 1, 2-dibromoethane gives rise to the corresponding 1, 1'; 3, 3'-doubly bridged diquaternary salts. The NMR spectra of the dimethylene-and trimethylene-bridged compounds are consistent with structures which ...
