Cinchona Alkaloid Squaramide Catalyzed Enantioselective Hydrazination/Cyclization Cascade Reaction of α-Isocyanoacetates and Azodicarboxylates: Synthesis of Optically Active 1,2,4-Triazolines

An efficient enantioselective hydrazination/cyclization cascade reaction of alpha-substituted isocyanoacetates to azodicarboxylates catalyzed by Cinchona alkaloid derived squaramide catalysts has been investigated, affording the optically active 1,2,4-triazolines in excellent yields (up to 99%) and good to excellent enantioselectivities (up to 97% ee) under mild conditions.