الفهرس 
Synthesis and Spectroscopic Studies of EnaminesDerivatives of p-Nitrobenzylcyanide, Coumarine andAntipyrineOnly 14 pages are availabe for public view
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Abstract
3-(Dimthylamino)-2-(4-nitrophenyl)acrylonitrile (3) has been used as a starting material. Compound 3 was prepared by reacting 2-(4-nitrophenyl)acetonitrile (1) with dimethylformamide dimethylacetal (DMFDMA) (2) in refluxing dry xylene. Trials to prepare the corresponding thiazolone derivative 5 from 3 by reaction with thioglycolic acid in dry pyridine gave the acid 4 in (85%) yield. Also, reaction of 1 with thioglycolic acid in dry pyridine gave the corresponding thiazolone 7 in yield 89%. Trials to prepare 5 by independent synthesis via reaction of 7 with DMFDMA in dry xylene were found failure and only the starting 7 a dark resin was formed. The reaction was performed in dry benzene at 60 ○C. Compound 9 was prepared by independent synthesis by the reaction of 12 with thioglycolic acid in dry pyridine. Compound 12 was formed as a coupling product of 1 with 8. Enaminonitrile 3 has been subjected to transamination reaction. Thus 3 reacted with 2-aminothiophenol (13) in refluxing glacial acetic acid to afford a product for which benzo[b][1,4]thiazepine (14). The thiazepine 14 was also prepared by independent synthesis from the reaction of 2-aminthiophenol (13) with 3-morpholino-2-(4-nitrophenyl)acrylo-nitrile (16) in glacial acetic acid. The later 16 was prepared from reaction of 1, morpholine and triethylorhoformate in dry xylene. The success of utility of N-morpholinomethylene-ρ-nitrobenzylcyanide (16) prompted us to extend this reaction on other aromatic amines and also with other new enamines. Compound 3 was also examined as a transamination reagent with m-anisidine (17) and with 3-chloro-4-methylaniline (18). Thus, reaction of 3 with 17 or 18 was carried out in refluxing glacial acetic acid for 3 hours to give the corresponding enaminonitriles 19 and 20 in excellent yields 82% and 85%, respectively. The same compounds 19 and 20 was obtained by independent method by reacting N-Morpholinomethyl-p-benzylcyanide (16) with the amines 17 and 18 in the same previous conditions used with enamine 16 to give 19 and 20 in moderate yields 65% and 54%, respectively. In contrast to the reaction of 3 with 2-aminothiophenol, reaction of 0-phenylenediamine (21) with 3 in glacial acetic acid was carried out and the obtained compound was found to be acyclic product 22. Also, reaction of 3 with 2-aminophenol (23) gave the corresponding acyclic 24. Although endocyclic nitrogen is the more nucleophilic one it’s also the more hidered, especially when 25 reacted with 3, which have a bulky attacking function in similar transamination reactions. Thus, 25 reacted with 3 in glacial acetic acid to give the corresponding 26 in good yield. Compound 28 reacted with morpholine and triethylorthoformate to the corresponding enaminonitrile 29 in good yield. Also, the reactivity 25 towards dimethylformamide dimethylacetal 2 was studies. Reaction of equimolecular amounts of 28 and DMFDMA in dry xylene for 3 hours gave a brown solid which was identified as 30. Also, compound 28 was examined toward ρ-bromobenzylidene-malononitrile (31). The reaction was carried out in absolute ethanol and catalytic amounts of piperidine. The reaction was resulted in the formation of 32 via Michael addition of activated methylene function in 28 to the ethylinic double bond in 31 followed by cycloaddition of endocyclic nitrogen to cyano group to give the final isolable product 32. Thus, cyanoacetylantipyrine (33) was subjected to the reaction with piperidine and triethylorthoformate in a molar ratio (1:1:1.2) to give the corresponding enaminonitrile 34. Also, the same condition was applied on the reaction of 33, morphline and triethylorthoformate to give 35 in good yield. Enaminonitrile 34 reacted with ρ-toluidine in glacial acetic acid to give the corresponding antipyrinylacrylonitrile 36. The same product was obtained by independent synthesis. Thus, reaction of 35 with ρ-toluidine under the same previous conditions. In the present work, α,α-diamine-β-cyano-β-arylazoethylenes (38a-i) were obtained in pure state and in high yields by heating the arylazomalononitriles (37a-i) with piperidine or morpholine in a molar ratio (1:1.2) in ethanol for few minutes. Thus, compounds 38a,b was prepared by reacting arylazomalononitriles 37a,b with piperidine or morpholine in molar ratio (1:1.2) in ethanol for 30 minutes. Structure of 38a,b was established by X-ray analysis. Also, reaction of arylazomalononirtiles 37c,d with piperidine or morpholine in absolute ethanol gave the corresponding enediamines 38c,d in 97, 96% yields respectively. Enediamines 38e,f were prepared by the previous method, but by adding 37e,f to piperidine or morpholine. By the same method, addition of arylazomalononirtiles 37g,h with piperidine or morpholine gave compounds 38g,h. Reaction of compound 37i with morpholine in absolute ethanol gave the compound 38i (cf. scheme 7). The obtained enediamines was converted to the starting arylazo analogues 37a-i by the action of glacial acetic acid. Also, reaction of 38a,b with hydrazines gave easily the corresponding known 3,5-diaminopyrazoles 41a,b in high yields. Compounds 41a,b was found identical with those obtained from reaction of 37a-i with hydrazines, via elimination of the more bulky subststituted secondary amines.