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Both metal-catalyzed and organocatalytic transfer hydrogenation reactions are widely employed for the reduction of CO and CN bonds. However, selective transfer hydrogenation reactions of CC bonds remain challenging. Therefore, the chemoselective transfer hydrogenation of olefins under mild conditions and in the absence of metal catalysts, using readily available and inexpensive reducing agents ( i.e. primary and secondary alcohols), will mark a significant advancement towards the development of green transfer hydrogenation strategies. Described herein is an unconventional catalyst-free transfer hydrogenation reaction of activated alkenes using isopropanol as an eco-friendly reductant and solvent. The reaction gives convenient synthetic access to a wide range of substituted malonic acid half oxyesters (SMAHOs) in moderate to good yields. Mechanistic investigations point towards an unprecedented hydrogen bond-assisted transfer hydrogenation process. 

The Ti^IV‐mediated synthesis of spirocyclicNH‐azetidines from oxime ethers using either an alkyl Grignard reagent or terminal olefin ligand exchange coupling partner is described. Through a proposed Kulinkovich‐type mechanism, a titanacyclopropane intermediate forms and serves as a 1,2‐aliphatic dianion equivalent, inserting into the 1,2‐dielectrophilc oxime ether to ultimately give rise to the desired N‐heterocyclic four‐membered ring. This transformation proceeds in moderate yield to furnish previously unreported and structurally diverseNH‐azetidines in a single step.

 

The Ti^IV‐mediated synthesis of spirocyclicNH‐azetidines from oxime ethers using either an alkyl Grignard reagent or terminal olefin ligand exchange coupling partner is described. Through a proposed Kulinkovich‐type mechanism, a titanacyclopropane intermediate forms and serves as a 1,2‐aliphatic dianion equivalent, inserting into the 1,2‐dielectrophilc oxime ether to ultimately give rise to the desired N‐heterocyclic four‐membered ring. This transformation proceeds in moderate yield to furnish previously unreported and structurally diverseNH‐azetidines in a single step.

 

A direct and general mono-arylation of activated C(sp³)–H bonds with nitroarenes under transition metal-free conditions has been developed.