The Study Of Multicomponent Tandem Reactions Of Malononitrile

Multicomponent reactions (MCRs) are one-pot processes in which several easily accessible components react to form a single product. They offer significant advantages over conventional linear-type syntheses due to their flexible, convergent and atom efficient nature and have become an important area of research in organic, medicinal and combinatorial chemistry. Malononitrile is an exceptionally versatile compound and is therefore used extensively as a reactant or reaction intermediate. It exhibits unique reactivity since the strongly electron-withdrawing cyano groups activate the methylene group, their polar multiple bond is suitable for nucleophilic addition and is also a good leaving group for substitution. This exceptional behavior makes malononitrile an important candidate for the design of new practical multicomponent reaction procedures. So we developed some new one-pot multicomponent reactions with malononitrile as one of the components in the reaction and found some intriguing results.1. Malononitrile was condensed with aromatic aldehydes to give arylidenemalononitriles in basic conditions, which were reacted with pyridinium saltes (N-ethoxycarbonylmethylpyridium bromide, N-phenacylpyridinium bromide, and N-N', N'-diethylaminocarbonylmethylpyridinium chloride) to give corresponding polysubstituted cyclopropanes. The polysubstituted cyclopropanes were fully characterized by NMR, IR spectra. The single crystal structures of five cyclopropanes were determined by X-ray diffraction method.2. Unprocedent polysubstituted benzene derivatives were produced in multi-component cyclization reactions of pyridine, ethylα-bromoacetate (methylα-chloroacetate), malononitrile and aromatic aldehydes in refluxing acetonitrile. The polysubstituted benzene derivatives were fully characterized by NMR, IR spectra and were confirmed by X-ray diffraction determined of five single crystal structures of polysubstituted benzene derivatives.3. Novel polysubstituted benzene derivatives and nitrogen containg heterocyclic compounds were produced in a multi-component cyclization reaction of pyridine, chloroacetonitrile, malononitrile and aromatic aldehydes in refluxing acetonitrile under the protection of nitrogen. All the compounds were fully characterized by NMR, IR spectra. the single crystal structure of six compounds and two intermediate compounds were determined by X-ray diffraction method.