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Catalytic Asymmetric Synthesis of 4‑Nitropyrazolidines: An Access to Optically Active 1,2,3-Triamines

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posted on 13.08.2014, 00:00 by Lennart Lykke, Bjørn Dreiø Carlsen, Raoní Scheibler Rambo, Karl Anker Jørgensen
The first catalytic enantio- and diastereoselective synthesis of 4-nitropyrazolidines is presented. Asymmetric hydrogen-bonding activation of nitro-olefins facilitated the 1,3-dipolar cycloaddition with hydrazones, affording optically active 4-nitropyrazolidines containing three continuous stereogenic centers as a single diastereomer in up to 99% ee. Furthermore, it is demonstrated that the optically active 4-nitropyrazolidines can be applied as precursors for the synthesis of highly interesting 1,2,3-triamines.