氮杂环卡宾催化α,β-不饱和酰氯与亚硝基化合物的[4＋2]环化反应

N-heterocyclic carbene-catalyzed [4 + 2] annulation of α,β-unsaturated acyl chlorides and nitroso compound

报道氮杂环卡宾催化的α,β-不饱和酰氯与亚硝基化合物的形式[4+2]环化反应合成氮杂-δ-内酯([1,2]嗪-6-酮)化合物.反应机理推测可能是卡宾进攻现场生成的烯基烯酮,得到烯基烯醇负离子,然后与取代的亚硝基苯发生[4+2]环合反应,从而得到的氮杂-δ-内酯产物.

The N-heterocyclic carbene-catalyzed [4 ＋ 2] annulation of α,β-unsaturated acyl chlorides with a nitroso compound was developed for the synthesis of aza-δ-lactones （2H-1,2-oxazin-6-one）.It is proposed that the catalytic reaction was initiated by the nucleophilic addition of the N-heterocyclic carbene to the vinylketenes in situ generated from the acyl chloride to give a vinylenolate,followed by the [4 ＋ 2] cycloaddition of the vinylenloate with nitroso compound to give the final aza-δ-lactones.