Phosphazene Superbase-Mediated Regio- and Stereoselective Iodoaminocyclization of 2‑(1-Alkynyl)benzamides for the Synthesis of Isoindolin-1-ones

Phosphazene superbase P4-t-Bu mediated iodoaminocyclization of 2-(1-alkynyl)­benzamides is reported. The reaction works under ambient conditions and instantaneously results in the synthesis of isoindolin-1-ones in 65–97% yields, in a regio- and stereoselective manner. The exclusive formation of products with Z-geometry (across the exo CC bond) has been confirmed through X-ray crystallography. The methodology also provides an easy access to aristolactams, an important class of natural products. This has been successfully demonstrated by synthesizing two aristolactam derivatives (including Cepharanone B).

本文报道了磷腈超强碱P4-t-Bu（Phosphazene superbase P4-t-Bu）介导的2-(1-炔基)苯甲酰胺（2-(1-alkynyl)benzamides）的碘胺环化反应（iodoaminocyclization）。该反应可在常温常压条件下进行，以区域及立体选择性的方式瞬时完成，以65%~97%的收率合成异吲哚啉-1-酮（isoindolin-1-ones）类产物。通过X射线晶体衍射（X-ray crystallography）分析证实，产物仅以外式碳碳双键（exo C=C bond）的Z-构型形式生成。该合成策略还可便捷地制备一类重要天然产物——马兜铃内酰胺（aristolactams）类化合物，通过合成两种马兜铃内酰胺衍生物（包含Cepharanone B），该方法的实用性已得到成功验证。