Pd(II)-Catalyzed Annulative Difunctionalization of Two Inert C(sp3)-H Bonds by a Bifunctional Reagent



Illustrated herein is a Pd(II) catalyzed one-pot direct difunc-tionalization of two distinct C(sp3)-H bonds [gem-ʹ-di-Me groups bearing aliphatic carboxylic acid] with bifunctional reagent (BFR) 2-iodo benzoic acid. The methyl 2-pyridyl sul-foximine (MPyS) bidentate directing group (DG), 2-chloro-5-trifluoromethyl ligand, and NaBrO3 co-oxidant combination helps the concerted metalation deprotonation (CMD) of inert C(sp3)-H bond as well reductive elimination steps; density functional theory (DFT) studies validate such insights. This process makes two [CC and CO] bonds of gem-ʹ-di-Me groups of DG-enabled aliphatic carboxylic acids in a single operation offering access to unusual benzo-fused peripheral substituted ω-membered lactones. This concept is uncovered for the first time. The transformation tolerates labile functional groups featuring broad scope with the construction of wide range of novel molecules of structural diversity. Ki-netic and control experiments study reveal the participation of monomeric-Pd-species on the catalytic cycle. Synthetic versatility of the complex molecular entities is also presented.


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