Aniline derivatives malononitrile

Azobenzenes 5 were synthesized by coupling of the dialkyl aniline derivative 2 with 4-nitro- or 4-methyl-sulfonylbenzene diazonium salt (Figure 3). Vinylidine compound 6 was prepared by Knoevenagel condensation of the corresponding aldehydes with malononitrile (Figure 4). 

Pyrrole 66 was prepared via a four-component coupling of glyoxal 64, aniline derivative 36, dimethyl acetylenedicarboxylate (65), and malononitrile (61) in good to excellent yields. A catalyst is not required the desired products are obtained simply by refluxing the four components in ethanol for 30 min. The functional group tolerance is somewhat limited however,... 

Among all the pyridine derivatives, 2-amino-3,5-dicyano-6-sulfanyl pyridines are even more interesting because of their potential therapeutic applications. In synthetic chemistry, the cyclocondensation of aldehydes, malononitrile, and thiols is the most straightforward pathway. In general, this transformation can be realized under basic conditions. The bases reported included EtsN, DABCO, piperidine, morpholine, thiomorpholine, pyrrolidine, N,N-DIPEA, pyridine, 2,4,6-collidine, DMAP, aniline, iV-methylaniline, A,A-dimethylaniline and N,N-diethylaniline. Reactions under neutral conditions have been explored as well. In these cases, Cul nanoparticles [75], ZnCl2 [76], and nanocrystalline magnesium oxide [77] have been applied as the catalysts. 

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