Tartaric acid–zinc nitrate has been found to be an efficient Brønsted acid-assisted Lewis acid catalytic system for the facile synthesis of β-amino carbonyl compounds through the one-pot Mannich reaction of aldehydes, aromatic amines and ketones in ethanol at room temperature. Remarkable enhancement of reactivity by tartaric acid (Brønsted acid) was observed in these reactions in the presence of anhydrous zinc nitrate (Lewis acid), due to coordination of the tartaric acid ligand to zinc ions increasing the acidity of the system. This procedure shows some advantages such as mild reaction conditions, short reaction times and high yields.
Biomimetic synthesis of 2-substituted N-heterocycle alkaloids by one-pot hydrolysis, transamination and decarboxylative Mannich reaction