Synthesis of benzopyranopyrrolidines via 1,3-dipolar cycloaddition of nonstabilized azomethine ylides with 3-substituted coumarins

A three-component reaction of 3-substituted coumarins with N-alkyl-α-amino acids and aldehydes gave 1-benzopyrano[3,4-c]pyrrolidines as a result of a 1,3-dipolar cycloaddition of an intermediate nonstabilized azomethine ylide at the double bond of the coumarin system in moderate to good yields. In most cases, high regio- and stereo-selectivity of the [3+2] cycloaddition was observed. © 2013 Elsevier Ltd. All rights reserved

An improved synthesis and some reactions of diethyl 4-oxo-4H-pyran-2,5- dicarboxylate

The reaction of ethyl 2-(dimethylamino)methylene-3-oxobutanoate with diethyl oxalate in the presence of sodium hydride in THF gave diethyl 4-oxo-4H-pyran-2,5-dicarboxylate, from which 4-oxo-4H-pyran-2,5-dicarboxylic and 4-oxo-1-phenyl-1,4-dihydropyridine-2,5-dicarboxylic acids and their derivatives were obtained in good yields. © 2013 Elsevier Ltd. All rights reserved

Novel fluorinated pyrimidines and pyridazines: synthesis and applications

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