Aqueous-phase catalytic oxidation, transfer hydrogenation, reductive amination and hydration reactions

• Water-soluble copper catalyst for oxidation of alcohols, alkylarenes and alkynes.
• Oppenauer-type oxidation catalyzed by water-soluble iridium catalyst.
• Meerwein–Ponndorf–Verley-type reduction catalyzed by water-soluble rhodium catalyst.
• Reductive amination catalyzed by water soluble palladium catalyst.
• Hydration of nitriles to amides catalyzed by water-soluble rhodium catalyst.

As part of our work devoted to the synthesis of organic compounds using “green” processes, we developed several water-soluble catalysts that allow efficiently the synthesis of ketones, amines, alcohols and amides. CuCl2·2H2O combined to 2,2′-biquinoline-4,4′-dicarboxylic acid dipotassium salt (BQC) was reported as an active catalyst for the selective oxidation with TBHP of alcohols, alkylarenes and alkynes. We developed also successfully hydrogen transfer reactions. While [Ir(COD)Cl]2/BQC proved to be efficient for Oppenauer-type oxidation of secondary alcohols, [Rh(COD)Cl]2/P(m-C6H4SO3Na)3 (TPPTS) showed very good activities for Meerwein–Ponndorf–Verley-type reduction of ketones and aldehydes. Higher alkylated amines and amides were also synthesized respectively, by direct reductive amination of aldehydes with primary and secondary amines catalyzed by water soluble Pd(PhCN)2Cl2/BQC, and hydration of nitriles with [Rh(COD)Cl]2/TPPTS. Many of these catalytic systems are recycled with no significant loss of activity and the final products are isolated in easy manners.

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