Studies On Catalytic Hydrogenation Of N-sulfonyl Ketimines And Nitrones

Nitrogen-containing compounds?such as sulfonamides,secondary amines,etc.?are a very important organic synthesis intermediates as the basic skeleton of many physiologically active natural products and pharmaceutical compounds.On the other hand,RnSiH_4–n/B?C₆F₅?₃ is a new type of catalytic reduction system that has received much attention in recent years.The catalyst system does not contain any metal and is environmentally friendly and has no metal residues.At the same time,these catalytic reactions can be carried out at normal temperature and pressure.In this paper,we chose B?C₆F₅?₃ as Lewis acid,chose cyclic sulfonimides and nitrone compounds as Lewis base,and methylphenylsilane as small molecule to explore and synthesize a series of potentially biologically active cyclic sulfonamides and benzyl.optimization conditions and range of use of amine compounds.By using catalytic system B?C₆F₅?₃/PhMeSiH₂ to catalyze the hydrogenation of cyclic sulfonimides,a simple,mild and low-cost metal-free catalytic system for the formation of cyclic sulfonamides was proposed.The yield was synthesized.74-99%of 23 aryl-substituted and heterocyclic-substituted cyclic sulfonamide compounds have realized the rapid and efficient construction of sulfonamide skeletons,which are important organic synthesis intermediates,and have potential application value.Based on the research literature and summarizing the experimental facts,a feasible reaction mechanism was proposed.Throughout the catalysis process,the cycle of Lewis acid-base was followed by the theory.Using B?C₆F₅?₃ as a Lewis acid,combined with a chiral thiourea catalyst and a chiral phosphoric acid catalyst to form a Lewis pair,tried to achieve asymmetric catalytic reduction of B?C₆F₅?₃/PhMeSiH₂on a cyclic sulfonimide,up to 9%of the enantioselectivity.The nitrone compound was reduced by the catalytic action of B?C₆F₅?₃/PhMeSiH₂ to obtain 12 kinds of aryl substituted and heterocyclic substituted secondary amine compounds with a yield of 24-85%.The method was simple,mild,and in the course of the reaction.Without the participation of metals,it was possible to quickly and efficiently construct an important secondary intermediate skeleton of organic synthesis intermediates.Based on the research literature and summarizing the experimental facts,the reaction mechanism of the first deoxygenation of nitrone to form an imine under the catalysis of B?C₆F₅?₃/PhMeSiH₂ and the reduction of the imine to form a secondary amine compound was proposed.