Synthesis of 2‐Alkenyl‐4H‐3,1‐Benzoxazin‐4‐Ones through HFIP‐Mediated Decarboxylative [4+2]‐Annulation of Isatoic Anhydrides with Cyclopropenones under Silver Catalysis

Abstract

We herein describes an HFIP‐mediated [4+2]‐cycloaddition reaction from simple and easily available isatoic anhydrides and cyclopropenones under silver catalysis. This transformation involves the tandem decarboxylative esterification, intermolecular addition, intramolecular substitution, small ring opening and isomerization processes, which allows the rapid assembly of versatile 2‐diarylalkenyl‐4H‐3,1‐benzoxazin‐4‐ones.

Palladium-catalysed dual ring-opening [3 + 4] annulation of isatoic anhydrides with cyclic iodoniums to build tribenzo[b,d,f]azepines and a mechanistic DFT study

“…On the other hand, isatoic anhydrides are readily available cyclic synthons. Low-valence metals are prone to become inserted into the C–O bonds of isatoic anhydrides, followed by subsequent decarboxylative and/or decarbonylative [3 + 2] or [4 + 2] cycloadditions with alkynes to obtain N-heterocycles, 11–14 but there has not been sufficient experimental and computational evidence to support any specific mechanism. In particular, there is no evidence for a process involving C–O bond activation and subsequent decarboxylation/decarbonylation.…”