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Paper | Regular issue | Vol 78, No. 2, 2009, pp.435-447
Published online, 6th October, 2008
DOI: 10.3987/COM-08-11524
Synthesis of Fluoroalkylated Dihydroazolo[1,5-a]pyrimidines and Their Ring-Chain Isomerism

Marina V. Goryaeva,* Yanina V. Burgart, Victor I. Saloutin, Elena V. Sadchikova, and Evgeny N. Ulomskii

*I. Ya. Postovsky Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, 620041, Russia

Abstract

Cyclisation of ethyl 2-ethoxymethylidene-3-polyfluoroalkyl-3-oxo-propionates with 3-amino-1H-[1,2,4]triazole, 3-amino-5-methylpyrazole, 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)aminomethylidene]propionates via opening of the heterocycle at the C-N bond. Dehydration of dihydroazolo[1,5-a]pyrimidine were realized.