Abstract
Hetaryl-substituted aminomethylenemalonates obtained by the condensation of aminoazoles with 2-alkoxymethylenemalonates are commonly used for the synthesis of biologically active azolopyrimidines [1, 2]. However, cyclization of hetaryl-substituted aminomethylenemalonates to give azolopyrimidines often proceeds only at high temperature or under upon microwave activation [1] or by using special reagents [2]. In the present work, we found that brief heating of diethyl aminomethylenemalonates 1a and 1b in ethanol in the presence of sodium ethylate leads to the formation of mesoionic 1,2,4-triazolo[4,3-a]pyrimidin-5-ones 2a or 2b in high yield. This reaction does not occur upon heating aminomethylenemalonates 1a or 1b with tertiary aliphatic amines in ethanol at reflux. However, heating esters 1 with primary or secondary amines in ethanol or acetonitrile at reflux leads to nucleophilic substitution of the malonate ester and formation of amidines 3a-c in high yield.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.