2-Substituted 3- acrylates flash vacuum thermolysis

Heating diethyl (2-pyridylamino)methylenemalonates 304 (R = COOEt, = Me, OH) in AcOH afforded 4-oxo-4//-pyrido[l, 2-n]pyrimidine-3-carboxylates 305 (R = Me, OH) (96JHC1041). Flash vacuum thermolysis of 2-substituted 3-(2-pyridylamino)acrylates 304 (R = CN, COOEt, R = H) through a packed silica tube (530 °C, 0.01 mmHg) gave 3-substituted 4//-pyrido[l,2-n]pyrimidm-4-ones 306 (R = CN, COOEt) (94AJC1263). Ethyl 7-methyl-4-oxo-l, 4-dihydro-1,8-naphthyridine-3-carboxylate (79%) was... 

The low-temperature, Mn(III)-oxidation of unsaturated derivatives of Meldrum s acid provides a route to cyclohexenes <02T25> and the readily available 5-substituted Meldrum s acids are a convenient source of a-substituted acrylate esters <02JOC7365>. Flash vacuum thermolysis of 5-aminomethylene derivatives of Meldrum s acid 26 generates imino-propadienones, RN=C=C=C=0 <02JOC8558>. 

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