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The synthesis of 3,3'‐bioxindoles employing deacylative alkylations (DaA) in one‐pot process, where the 3‐bromooxindoles are generated in situ, is described. Good yields and moderate diastereoselections are obtained. By the modification of this procedure the synthesis of pure 3‐bromooxindoles through a deacylative bromination (DaB) is achieved. These bromides are efficiently employed in a photoredox dimerization process to get the desired 3,3'‐bioxindoles in good yields and low diastereoselections. In this single‐electron‐transfer (SET) mechanism the presence of a high quantum‐yield iridium(III) complex ensures high conversions in short reaction times. [ABSTRACT FROM AUTHOR]

Herein we introduce the recent developments of a new strategy based on deacylative alkylation (DaA) reactions for the generation of quaternary stereocenters based on the in situ preparation and functionalization of enolates under very mild reaction conditions. Palladium‐catalyzed deacylative allylation and benzylation reactions of carbon nucleophiles are performed with the corresponding alcohols. This methodology has been applied to the synthesis of the calcium ion channel blocker verapamil, the antiviral (+)‐hamigeran B, several oxindole precursors of esermethole, horsfiline, physostigmine, phenserine, meso‐folicanthine, meso‐chinonanthine and the dimer cyclotriptamine alkaloids. Base‐promoted deacylative reactions enable the functionalization of 2‐oxindole enolates at the 3‐position with alkyl halides and electrophilic alkenes. In the presence of oxygen or air, 3‐hydroxy‐2‐oxindoles are prepared by deacylative oxidation. Detrifluoroacylative reactions are promoted by a base generating fluoroenolates, which can participate in aldol, Mannich and Michael reactions for the preparation of important fluorinated intermediates. Finally, palladium‐catalyzed deacylative cross‐coupling of acetyl diazoacetates and phosphonates with aryl iodides let to the formation of aryl diazoacetates and phosphonates, respectively. The same process, with 2‐iodoazoarenes and 2‐iodoaryltriazenes, gives 2H‐indazoles, which are important pharmacophores. [ABSTRACT FROM AUTHOR]

An innovative and efficient monoalkylation and nonsymmetrical 3,3-dialkylation of oxindoles has been achieved. First, the monoalkylation of 3-acetyl-2-oxindoles can be performed in good yields under mild reaction conditions using alkyl halides and benzyltrimethylammonium hydroxide (Triton B) as base at room temperature. This methodology is applied to construct the synthetically challenging compound 1,3-dimethyl-2-oxindole. Subsequent deacylative alkylation (DaA) of the alkylated 3-acetyl-2-oxindoles with alkyl halides takes place efficiently using LiOEt or by conjugate addition with electron-deficient alkenes in the presence of Triton B at room temperature under argon, affording the corresponding unsymmetrically 3,3-disubstituted 2-oxindoles. This simple methodology has been applied to the synthesis of precursors of horsfiline, esermethole, physostigmine, and phenserine alkaloids. [ABSTRACT FROM AUTHOR]