Carbon–carbon bond formation by intramolecular 1,4-dipolar cycloaddition: heterocyclic betaines generated in situ from amides and N-substituted amides
作者:Kevin T. Potts、Maurice O. Dery、Rudolph K. Kullnig
DOI:10.1039/c39870000840
日期:——
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.
苯甲酰胺和N-取代的苯甲酰胺与适当的邻-烯基和-炔基侧链以及(氯羰基)苯基乙烯酮的反应得到瞬态的脱水-1,3-恶嗪鎓氢氧化物,其容易经历分子内的1,4-偶极环加成;从这些1:1-环加合物中损失的CO 2与N-取代的体系和烯基侧链可分离,得到chromeno [4,3 - b ]吡啶-2-酮。