The Synthesis Of Spiropyrazolines And Sulfinates And Conjugate Reduction Of Chalcones

Sulflonyl hydrazides are low toxic and safe, and thus have been widely used in organic chemistry. Hydrazones, which are readily obtained by the condensation of aldehydes or ketones with commercially available sulflonyl hydrazides, represent an important source of stable nitrogenated compounds. Recently, hydrazones have emerged as divergent reagents that have been used as in situ source of diazo compounds in the synthesis of nitrogen heterocyclic compounds. Besides, hydrazones have been used as the source of sulfone groups.Basing on the characteristics of hydrazones mentioned above, this thesis includes catalyst- free synthesis of spiropyrazolines from chalcones and hydrazones, conjugate reduction of chalcones with tosylhydrazines, and intramolecular rearrangement of hydrazones to sulfinates.Treatment of N-tosylhydrazones with chalcones in the presence of cesium carbonate at 110℃ affords spiropyrazolines with high selectivity and excellent yields. This protocol possesses many advantages such as readily available and stable starting materials, high selectivity, operational simplicity, and catalyst-free conditions.During the synthesis of spiropyrazolines, a chemoselective conjugate reduction of chalcones with tosylhydrazine has been developed to afford the corresponding saturated ketones in moderate to good yields. These reactions are simple and economic. Firstly, the reduction of chalcone was used as the probe for the evaluation of the reaction conditions. Finally, with the optimized reaction conditions in hand, the scope of the reaction was subsequently investigated.As reported in literature, sulfinates exhibited antibiotic activity against a human leukaemia which has attracted increasing attention. This thesis describes that hydrazones undergoes rearrangement to afford sulfinates in the present of DIPEA. It is worth noting that these reactions agree well with the requirements of sustainable chemistry as water and nitrogen are the only byproducts.