Investigation On The Asymmetric Transfer Hydrogenation Of β-Oxosulfonamides And The Organocatalytic Synthesis Of 5-Hydroxypyrazolidines

1. Investigation on the Asymmetric Transfer Hydrogenation ofβ-OxosulfonamidesA series ofβ-oxo-sulfonamides were synthesized from the corresponding aromatic ketones. The asymmetric transfer hydrogenation of theβ-oxo sulfonamides, using (S,S)-RuCl[N-(tosyl)-1,2-diphenylene-diamine](p-cymene) as the catalyst and HCOOH-Et3N as the hydrogen source, was then investigated. The effects of solvent and catalyst loading on the reaction were firstly explored to optimize the reaction conditions, using N-(4-Chlorophenyl)-2-hydroxy-2-phenylethanesulfonamide as the model, and finally, a series of the corresponding chiralβ-hydroxy sulfonamides were prepared successfully in good to excellent yields (75%–95%), with outstanding enantioselectivities (97% to >99% ee).2. Investigation on the Organocatalytic Synthesis of 5- HydroxypyrazolidinesWe synthesized a series of di-substituted hydrazines and substituted cinnamaldehyde. Synthesis of pyrazolidine-containing compound from these materials by organocatalytic domino reaction with iminium mechanism was then investigated.The reaction coditions were optimized by exploring a series of secondary amine catalysts, solvents and additives. A number of 5-hydroxypyrazolidines, including racemic and optically active ones, were obtained in good yields.