Synthesis
General procedure: o-chlorobenzaldehyde (1 mmol), ethyl acetoacetate (1 mmol; 0.132 g) and thiourea (1.5 mmol; 0.114 g) were added in a round bottom flask, followed by the addition of nanomaterials of silica disulfate (NMSDSA) (10 mol%; 0.024 g) or nanomaterials of silica monosulfate sodium salt (NMSMSA) (10 mol%; 0.018 g) as catalysts. The reaction mixtures were stirred without magnetic stirring at 80 °C under solvent-free conditions. The reaction progress was monitored by TLC (unfolding agent: hexane/ethyl acetate, 5:2). Upon completion of the reaction, ethyl acetate (10 mL) was added to the mixture, stirred and refluxed for 5 min, followed by washing with water (10 mL). The aqueous and organic phases were separated by decantation (the reaction product was soluble in hot ethyl acetate, while the NMSDSA or NMSMSA catalyst was soluble in water). The solvent in the organic phase was evaporated and the crude product was purified by recrystallization from ethanol/water (10:1) to give ethyl 4-(2-chlorophenyl)-6-methyl-2-thio-1,2,3,4-tetrahydropyrimidine-5-carboxylate.
References
[1] Synthetic Communications, 2013, vol. 43, # 11, p. 1477 - 1483
[2] Chinese Journal of Chemistry, 2011, vol. 29, # 9, p. 1863 - 1868
[3] Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 2007, vol. 46, # 12, p. 2045 - 2048
[4] Synthetic Communications, 2009, vol. 39, # 5, p. 880 - 886
[5] Tetrahedron Letters, 2009, vol. 50, # 24, p. 2889 - 2892
