and diastereoselective synthesis of 4-nitropyrazolidines is presented. Asymmetric hydrogen-bonding activation of nitro-olefins facilitated the 1,3-dipolar cycloaddition with hydrazones, affording opticallyactive 4-nitropyrazolidines containing three continuous stereogenic centers as a single diastereomer in up to 99% ee. Furthermore, it is demonstrated that the opticallyactive 4-nitropyrazolidines