Organocatalytic Enantioselective Hydroxymethylation of Oxindoles with Paraformaldehyde as C1 Unit
摘要:
A bifunctional thiourea-tertiary amine-catalyzed asymmetric hydroxymethylation of 3-substituted oxindoles using paraformaldehyde as the C1 unit was developed. A wide scope of oxindoles, bearing C3 sterically congested quaternary carbon centers, were smoothly obtained in good to excellent yields (up to 99%) and high enantioselectivities (up to 91% ee) under mild reaction conditions. A more significant feature of this approach employs cheap and readily available paraformaldehyde as a hydroxymethylation Cl unit, which is activated by chiral bifunctional thiourea organocatalysts.
A bifunctional thiourea-tertiary amine-catalyzed asymmetric hydroxymethylation of 3-substituted oxindoles using paraformaldehyde as the C1 unit was developed. A wide scope of oxindoles, bearing C3 sterically congested quaternary carbon centers, were smoothly obtained in good to excellent yields (up to 99%) and high enantioselectivities (up to 91% ee) under mild reaction conditions. A more significant feature of this approach employs cheap and readily available paraformaldehyde as a hydroxymethylation Cl unit, which is activated by chiral bifunctional thiourea organocatalysts.
Chiral Scandium-Catalyzed Enantioselective Hydroxymethylation of Ketones in Water
Form with formalin: Scandium‐catalyzed enantioselective hydroxymethylation of ketones has been developed usingaqueousformaldehyde (formalin) in water. The addition of a catalytic amount of pyridine enables the use of ketones directly in asymmetric hydroxymethylation reactions.