A new class of hybrid molecules based on azolo[1,5-a]pyrimidin-7-ones and 3-ethoxycarbonyl-1-ethyl-6-fluoroquinolin-4(1H)-one linked by a 1,2,3-triazole spacer

An atom-efficient synthesis of hybrid molecules based on 7-azido-3-ethoxycarbonyl-1-ethyl-6-fluoroquinolin-4(1H)-one and 4-(prop-2-yn-1-yl)azolo[1,5-a]pyrimidin-7-ones by the azide-alkyne cycloaddition was developed. The synthetic approaches to precursors of hybrid molecules, 4-(prop-2-yn-1-yl)azolo[1,5-a]pyrimidin-7-ones, by alkylation of the corresponding NH-acids were optimized. Alkylation of 1,2,4-triazolo[1,5-a]pyrimidin-7-ones gave the products of alkylation at N(3) and N(4) atoms. Conditions for regioselective synthesis of N(4)-(prop-2-yn-1-yl)triazolopyrimidines were developed.