Carbon–carbon bond formation by intramolecular 1, 4-dipolar cycloaddition: heterocyclic betaines generated in situ from amides and N-substituted amides
KT Potts, MO Dery, RK Kullnig
文献索引：Potts, Kevin T.; Dery, Maurice O.; Kullnig, Rudolph K. Journal of the Chemical Society, Chemical Communications, 1987 , p. 840 - 842
Reaction of benzamides and N-substituted benzamides with appropriate o-alkenyl and- alkynyl side-chains and (chlorocarbonyl) phenyl ketene gives transient anhydro-1, 3- oxazinium hydroxides which readily undergo intramolecular 1, 4-dipolar cycloaddition; loss of CO2 from these 1: 1-cycloadducts, isolable with N-substituted systems and alkenyl side- chains, gives chromeno [4, 3-b] pyridin-2-ones.
