SYNTHESIS OF FLUOROALKYLATED DIHYDROAZOLO[1,5-a]PYRIMIDINES AND THEIR RING-CHAIN ISOMERISM

摘要

Cyclisation of ethyl 2-ethoxymethylidene-3-polyfluoroalkyl-3-oxo-propionates with 3-amino-1H-[1,2,4]triazole, 3-amino-5-rnethylpyrazole, ethyl 3-aminopyrazole-4-carboxylate and ethyl 5-aminoimidazole-4-carboxylate hydrochloride results in the formation of polyfluoroalkylated dihydroazolo[1,5-a]pyrimidines. The latter are subject to ring-chain isomerisation in solutions depending on the solvent and the "length" of the fluoroalkyl substituent to yield ethyl 3-polyfluoroalkyl-3-oxo-2-[(azol-3-yl)aminornethyli-dene]propionates via opening of the heterocycle at the C-N bond. Dehydration of dihydroazolo[1,5-a]pyrimidine were realized.