Divergent Reaction of Indoline‐derived Azadienes withα‐Bromohydroxamates: Synthesis of Spiro‐indolinepyrrolidinones and Indoline‐fused Diazepinones

Abstract

A divergent reaction of indoline-derived azadienes with α-bromohydroxamates for the selective synthesis of spiro-indolinepyrrolidinones and indoline-fused diazepinones was disclosed. This reaction sequence involved an initial formation of five-membered spirocyclic products followed by an intramolecular ring-opening and ring expansion to produce seven-membered diazepinones. We demonstrated that controlling the reaction time could modulate the reaction pathway for formation of different molecular frameworks for the same set of substrates. Based on the experimental results, the reaction mechanism was also discussed and proposed to explain the phenomena observed in the process.

Base-Promoted Formal (3 + 2) Cycloaddition of α-Halohydroxamates with Electron-Deficient Alkenyl-iminoindolines To Synthesize Spiro-indolinepyrrolidinones

“…For example, imines, as a traditional class of electrophile, were successfully applied in the (3 + 2) cyclization with aza-oxyallyl cations by several groups (Scheme a) . Interestingly, unsaturated imines provide different regioselectivity where aza-oxyallyl cations more likely reacted with the aza-diene moiety to enable formal (4 + 3) cycloaddition . Obviously, there is another possible regioselectivity of aza-dienes where the C–C double bond acts as the reactive species.…”