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

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.