Novel green technologies for the synthesis of biologically important molecules in nearcritical water and ionic liquids.

摘要

There is a growing interest among the pharmaceutical and the chemical industries to develop processes and technologies that are environmentally friendly (green chemistry). An important area of research toward this goal deals with the reduction in the amount of organic solvents used as reaction media. In recent years water (under the conditions of heat and pressure) and ionic liquids have been emerging as viable substitutes for organic solvents. We have attempted to develop novel technologies for the synthesis of biologically and industrially important molecules using water and ionic liquids as the reaction media.;Water has been shown to be a useful green medium for the reduction of various aromatic nitro compounds to amines using HCO2Et as the reducing agent. These reductions were carried out at a temperature well below what has been generally described as the nearcritical range for water.;Quinolines are an interesting class of heterocyclic molecules that show a wide range of biological activity (as antimalarial, anti-inflammatory, and anticancer agents). The synthesis of quinoline derivatives via various green routes is one of the main focal points of this dissertation. This has been achieved in nearcritical water using several different starting materials and reagents (2-nitrobenzaldehyde, anthranil, 2-nitrobenzaldoxime, isatin etc.). In addition to quinolines, a benzisoxazole has been prepared in hot pressurized water via nucleophilic aromatic substitution on a benzene ring.;Indium and gallium have recently emerged as promising mediators of various reactions (allylation, propargylation, Reformatsky etc.). Some efficient and green indium and gallium mediated reactions of ally halides with carbonyl groups have been developed in water. Indium mediated synthesis of quinolines using isatin and alpha-haloketone has also been achieved in nearcritical water. In addition, novel methodologies for the synthesis of quinolines have been developed in water as well as ionic liquids using indium and HCO 2NH4 as the reducing agents.