NaOAc-Promoted [3+1+2]\nAnnulation of <i>O</i>‑Pivaloyl Oximes, Aldehydes,\nand 2‑Methylbenzothiazole\nSalts: Synthesis of 1‑Azaphenothiazines

This paper presents an efficient strategy for constructing\n1-azaphenothiazines\nthrough the NaOAc-promoted [3+1+2] annulation of <i>O</i>-pivaloyl oximes, aldehydes, and 2-methylbenzothiazole salts. The\nreaction is conducted in ethanol and employs oxygen as the oxidant\nunder catalyst-free conditions. The process is amenable to various <i>O</i>-pivaloyl oximes, 2-methylbenzothiazole salts, and aldehydes,\naffording the target products in satisfactory yields.