Synthesis of 4-Alkynyl-substituted 3,4-Dihydropyrimidin-2(1H)-ones

Abstract

4-Alkynyl-3,4-dihydropyrimidin-2-(1H)-ones were synthesized by a one-pot reaction of propynals, ethyl acetoacetate, and urea. The yields of acetylenic dihydropyrimidinones depend significantly upon the propynal structure and catalyst type. A comparative study of the catalysts revealed an important advantage of polyphosphate ester in tetrahydrofuran in comparison with hydrochloric acid in methanol or trimethylchlorosilane in dimethylformamide, allowing the preparation of target compounds in good or moderate yields.

GRAPHICAL ABSTRACT

Keywords:

• Biginelli reaction
• 3,4-dihydropyrimidin-2-ones
• multicomponent reactions
• propynals

ACKNOWLEDGMENT

The authors thank the Russian Foundation for Basic Research (10-03-01024-a) for financial support.

Notes

^a Method A: HCl/MeOH, reflux, 24 h.

^b Method B: 1.2 equiv Me₃SiCl/DMF, rt, 72 h.

^c Method C: PPE/THF, reflux, 24 h.

^d Resinification.