Methylene Insertion into Nitrogen‐Heteroatom Single Bonds of 1,2‐Azoles via a Zinc Carbenoid: An Alternative Tool for Skeletal Editing

Abstract The nitrogen‐heteroatom single bonds of 1,2‐azoles and isoxazolines underwent methylene insertion in the presence of CH 2 I 2 (6 equiv.) and diethylzinc (3 equiv.) to produce a wide variety of the ring‐expanded six‐membered heterocycles. Density functional theory calculations suggest that the methylene insertion proceeds via cleavage of nitrogen‐heteroatom single bonds followed by ring closure.