P. Kumar et al., AN EFFICIENT SYNTHESIS OF QUINOLONES USING N-PHENYL(TRIPHENYLPHOSPHORANYLIDENE)ETHENIMINE, Tetrahedron letters, 35(49), 1994, pp. 9229-9232
The acylphosphoranes 5 formed in a highly selective and sequential man
ner from the reaction of N-substituted anthranilic acids 1 and N-pheny
l(triphenylphosphoranylidene)ethemine ethenimine 2 undergo intramolecu
lar Wittig cyclization on the imide carbonyl to afford the pyrrolo- an
d pyrido[1,2-a]quinolones 6 in moderate to good yields.