Study On The Green Method Of The C-N Bond Formation Reactions

The C-N bond formation reactions play important roles in the methodologies of organic synthesis. Such reactions can afford amines and its derivatives and nitrogen-containing heterocycles, which are kinds of valuable compounds possesing important biological and pharmaceutical activities or useful synthones for the synthesis of various pharmaceutical and bioactive heterocycles. Because of prominent role of their products, the C-N bond formation reactions have attracted considerable attention of organic worker. Moreover, carrying out organic reactions under the green condition has become highly desirable in recent years. In this dissertation, we studied C-N bond formation by rearrangement and condensation reactions which were also investigated on greener pathway.1. The conversion of heterocyclic ylthio (yloxy) secondary benzamides into substituted heterocyclic amines mediated by metallic hydrides via a novel reductive rearrangement pathway forming C-N bond was investigated. Afforded substituted heterocyclic amines are a kind of important biologically active compounds which have aroused considerable interest and attention in drugs and pesticides. We explored the novelty, applicability and mechanism by studying the reactions of different substrates and metallic hydrides. Our finding provides a new route to prepare substituted heterocyclic amines which can be protected against oxidation in reductive condition and can be afforded by an atom-economic rearrangement pathway. Our finding also the first insight into a novel hydride-promoted reductive rearrangement of amides.2. Two green and efficient pathways to pyrazoles, diazepines, enaminones and enamino esters were developed. Pyrazoles, diazepines are kinds of valuable bio-active heterocycles. In addition,β-enaminones and -enamino esters are useful synthones for the synthesis of various pharmaceuticals and bioactive heterocycles. (1). Room temperature condensation of hydrazines/hydrazides, diamines and primary amines with various 1,3-dicarbonyl compounds to form C-N bond in pure water in presence of a catalytic amount of H3PW12O40 as a heterogeneous inorganic catalyst was adopted. (2). Room temperature solventless condensation of hydrazines/hydrazides, diamines and primary amines with variousβ-dicarbonyl compounds to form C-N bond in the presence of H2SO4·SiO2 as a heterogeneous catalyst was adopted. The aqueous medium or solvent-free conditions, simple experimental procedure, mildness of the conversion, high yields and chemo-and regioselectivities and reusability of the catalyst are the noteworthy advantages of the protocol.3. We developed a green and efficient pathway to-amino carbonyl and nitrile compounds which have attracted considerable attention in organic synthesis because of their wide range of biological activities and pharmacological properties. Room temperature Michael additions of various aliphatic and aromatic amines to a,-unsaturated esters and acrylonitrile to form C-N bond in pure water in presence of a catalytic amount of H3PW12O40 as a reusable catalyst was adopted. The aqueous medium, simple experimental procedure, mildness of the conversion, high yields, participation of wide range of substrate including aromatic amines, employment of a catalytic amount of the catalyst and reusability of the catalyst are the noteworthy advantages of the protocol.