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Synthesis of 4-(1,3,5-thiadiazinan-2-ylidene)-2-(3,4-dihydro-2H-1,3,5-thiadiazin-6-yl)pent-2-enedinitriles
* 1, 2, 3 , 4 , 2, 5
1  Kuban State University, 149 Stavropolskaya Str., Krasnodar 350040, Russian Federation
2  ChemEx Lab, Vladimir Dal’ Lugansk National University, Lugansk, 91034 Russia.
3  North-Caucasus Federal University, 1 Pushkina St., 355009 Stavropol, Russian Federation
4  The Federal State Unitary Enterprise "Institute of Chemical Reagents and High Purity Chemical Substances" of National Research Centre "Kurchatov Institute", 3 Bogorodsky Shaft, Moscow 107076, Russia
5  Lugansk State Medical University, 1-g 50 years of Lugansk Defence, Lugansk 91045, Russia


The reaction of cyanothioacetamide with diethyl ethoxymethylenemalonate in the presence of triethylamine in hot EtOH proceeds non-selectively and leads to the formation of a mixture of triethylammonium 1,5-diamono-2,4-dicyano-5-thioxopenta-1,3-diene-1-thiolate (minor) and triethylammo-nium 3-cyano-5-ethoxycarbonyl-6-oxo-1Н-pyridine-2-thiolate (major). Upon treatment with primary amines and 37% aqueous HCHO in the boiling aqueous ethanol, the reaction product affords only 4-(1,3,5-thiadiazinan-2-ylidene)-2-(3,4-dihydro-2H-1,3,5-thiadiazin-6-yl)pent-2-enedinitrile derivatives, instead of the expected pyrido[2,1-b][1,3,5]thiadiazines. Triethylammonium 3-cyano-5-ethoxycarbonyl-6-oxo-1Н-pyridine-2-thiolate does not react under these conditions. The structure of the resulted products was confirmed by means of NMR, IR spectroscopy and LCMS. The mechanism of the formation of the products is discussed.

Keywords: cyanothioacetamide, diethyl ethoxymethylenemalonate, aminomethylation, Mannich reaction, 1,3,5-thiadiazines