Rh-Catalyzed One-Pot Reductive Alkylation of Malononitrile Under Transfer Hydrogenation Conditions

Abstract

Efficient synthesis of monosubstituted malononitriles was achieved by one-pot reductive alkylation of malononitrile with carbonyl compounds via [Cp*RhCl₂]₂-catalyzed transfer hydrogenation reaction.

Keywords:

• Monosubstituted malononitrile
• reductive alkylation
• rhodium
• transfer hydrogenation

Notes

^a Reaction conditions: 0.5 mmol benzaldehyde, 0.5 mmol malononitrile, metal complex (0.5 mol%), 1.5 mL solvent, and 0.2 mL HCOOH–Et₃N (5:2) at 40 °C for 1 h.

^b Isolated yield.

^c Benzylidenemalononitrile was isolated in 82% yield.

^d Benzylidenemalononitrile also isolated (58%).

^e Benzylidenemalononitrile also isolated (32%).

^f Benzylidenemalononitrile also isolated (62%).

^g With neat formic acid–triethylamine azeotropic mixture (0.5 mL).

^a Reaction condition: 0.5 mmol aldehyde/ketone, 0.5 mmol malononitrile, [Cp*RhCl₂]₂ (0.5 mol%), 1.5 mL CH₂Cl₂, and 0.2 mL HCOOH–Et₃N (5:2) at 40 °C.

^b Isolated yield.

^c 1.2 equiv. of aldehyde was used due to evaporation.

^d 1.2 equiv. of ketone was used due to evaporation.