Polycondensed Heterocycles. VII. A Convenient Synthesis of Pyrrolo[1,2-a]quinoxaline Derivatives by Intramolecular Aromatic Nucleophilic Displacement (original) (raw)
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Zeitschrift für Naturforschung B, 1986
3-Thiocyanatomethyl C innam onitrile, R eductive Cleavage, Pyrrole Derivatives /3-Thiocyanatomethyl cinnam onitrile derivatives coupled with aromatic diazonium salts to afford the corresponding azo com pounds, which undergo reductive cyclization into pyrrole derivatives. The utility of organic cyano com pounds in heterocyclic synthesis has recently received consider able attention [1, 2], Our group has been involved in the last years in a program aiming to develop effi cient procedures for synthesis of polyfunctionally substituted azoles [3, 4], azines [5, 6 ] and their con densed derivatives [7, 8 ] utilizing simple and readily obtainable polyfunctionally substituted nitriles. D u ring this phase of our research we could show that whereas ethylidenem alononitrile derivative l a does not couple with aromatic diazonium salts, the pre sence o f cyano substituent on the methyl m oiety (as in lb ) sufficiently activates the adjacent m ethylene group for coupling [9], The resulting hydrazones could be utilized for synthesis of pyridazine-6 -imine derivatives [10]. It seem ed to us of value to see if the presence of other functional substituent on the methyl m oiety in 1 can effect similar activation.
Archives of Pharmacal Research, 1994
Phenylazocyanothioacetarnide 1 reacts with malononitrile to afford the pyridinethione 4 which reacts with phenacylbromide to yield the p~dine-S-phenacyl derivative 6. 1 reacts with ethyl cyanoacetate to yield the pyridazine derivative, 8, and with phenacyl bromide to afford the N-phenao/I derivative 11, instead of the thiazole 10. Compound 11 afforded the pyrazolopyridine 13 on reaction with malononitrile while 10 was obtained on coupling of the thiazole 14 with diazotised aniline. Compound 10 reacts with malononitrile to afford the thiazolyl pyridazine 15. Compound 1 reacts with maiononitrile dimer to afford the pyridopyridazine derivative 17a. 1 reacts also with active methylene heterocycles to afford the pyrazolo and thiazolo-fused pyridazines 20 and 23 respectively.
Molecules, 2009
Phenacylmalononitrile 1 reacts with dimethylformamide dimethyl acetal to yield an enaminone which could be readily converted into a pyrrole or an aminopyridazine by treating with ammonium acetate and hydrazine hydrate, respectively. Compound 1 reacted with hydrazine hydrate in ethanol at room temperature to yield the dihydropyridazine 9 as a single product. In refluxing ethanol this product further reacted with hydrazine hydrate to yield the novel dihydropyrazolopyridazinamine 10.
ChemInform, 2007
4-Hydroxy-1-methyl-3-[E-3-(4-oxo-4H-chromen-3-yl)acryloyl]quinolin-2(1H )-one (3) was smoothly obtained via a one-pot aldol dehydration reaction of 3-acetyl-4-hydroxyquinolin-2(1H)-one with 3-formylchromone and was utilized to prepare miscellaneous triheterocyclic systems containing the quinolinone moiety. Both the a,b-unsaturated ketone side chain and the g-pyrone ring in compound 3 were subjected to nucleophilic cyclization with certain 1,2-and 1,3-bifunctional N,N-, N,O-, N,C-, and O,C-nucleophiles under different reaction conditions. Many pyrazolinyl-, isoxazolinyl-, pyrimidinyl-, and pyridinylquinolinones bearing other six-or five-membered heterocyclic systems have been conveniently synthesized using more than one synthetic route. 330 b-proton is considerably shifted to d ¼ 9.24 as doublet (J ¼ 16 Hz). The structure is assuming E-form, which suffers anisotropic effect due to the neighboring C5 5O of chromone system.