Title:Green and Regioselective Alkylation of Dihydropyrimidinthiones through
Michael Addition
Volume: 20
Issue: 12
Author(s): Fatemeh Yaghoubi, Gholamhassan Imanzadeh*, Roghayyeh Asgharzadeh, Zahra Soltanzadeh and Turan Öztürk
Affiliation:
- Department of Chemistry, Faculty of Sciences, University of Mohaghegh Ardabili, 56199-11367, Ardabil, Iran
Keywords:
Dihydropyrimidin-2(1H)-thiones, aza-michael addition, high regioselective synthesis, sulfur-containing compounds, tetrabutylammonium bromide, green conditions.
Abstract: Dihydropyrimidines are one of the most important heterocyclic ring systems having a serious
place in medicinal and organic synthesis. In this paper, a new series of dihydropyrimidines consisting
of sulfur atoms were synthesized using inorganic base K2CO3 and TBAB as an organic salt to
make high polarity in reaction media. Interestingly, different 3,4-dihydropyrimidin-2(1H)-thiones reacted
smoothly with various acrylic esters to afford adducts via highly regioselective N3-Michael addition
reaction was carried out at 100oC in 12 h. result: Unfortunately, the reaction failed with fumaric
esters owing steric effects. Avoiding organic solvents during this reaction effectively led to the development
of an economic approach. Structures of the new compounds were established on the basis of
1H NMR, 13C NMR, and IR spectral data.