_Molbank_**2010**, M655  
_Molnak_  
**ISSN 1422-8599**  
www.mdpi.com/journal/molbank  
_Short Note_  
Ethyl 2-[(_Z_)-2-(4-Cyanophenyl)-2-hydroxyvinyl]-4-(4-methoxy-phenyl)-6-methyl-1,4-dihydropyrimidine-5-carboxylate  
**[PERSON] 1, [PERSON] 1 and [PERSON] 2,*  
Footnote 1: The \(\alpha_{1}\)-\(\alpha_{2}\)-\(\alpha_{3}\) plane is the \(\alpha_{1}\)-\(\alpha_{2}\) plane, and the \(\alpha_{1}\)-\(\alpha_{2}\) plane is the \(\  
1,2,3,4-tetrahydropypyrimidine-5-carboxylate (**1**) in a one-pot, two-step synthesis (Scheme 1). The reaction sequence includes the S-alkylation of DHPM **1** by the \(\alpha\)-bromoketone **2**. The resulting intermediate undergoes in the presence of triphenylphosphine an Eschenmoser sulfide contraction to yield the desired product **3**[5]. Separation of the arising triphenylphosphine sulfide from the reaction mixture can be done by column chromatography, but is not an easy task. To prevent this costly separation procedure, we chose the application of polymer-bound triphenylphosphine. The reaction selectivity and yields of both phosphine agents are comparable. The presented synthetic method is well suited for a diversity-oriented synthesis strategy, using differently substituted Bignelli compounds and various \(\alpha\)-bromoketones. **Scheme 1. ** DHMP **1** alkylation/sulfide contraction sequence yielding product **3**. The title compound **3** has been fully characterized by \({}^{1}\)H- and \({}^{13}\)C-NMR, IR, Raman and ESI-TOF MS analysis. It was observed that the \({}^{1}\)H NMR spectra of **3** show a duplicate set of some signals (approximately 3:1 ratio) due to different conformers of **3** in solution. No tautomeric form of **3** was observed in the NMR experiments. The \({}^{1}\)H NMR as well as the \({}^{13}\)C NMR did not show appropriate signals for the expected aliphatic CH\({}_{2}\) group of a keto tautomer. **Experimental Procedure**  
To a suspension of ethyl 4-(4-methoxyphenyl)-6-methyl-2-thioso-1,2,3,4-tetrahydropyrimidine-5-carboxylate **1** (110 mg, 0.36 mmol, 1 equiv) in acetone (2 mL), powdered K\({}_{2}\)CO\({}_{3}\) (75 mg, 0.54 mmol, 1.5 equiv) and 2-bromo-4'-cyanoacetophenone **2** (96 mg, 0.43 mmol, 1.2 equiv) were added subsequently. The reaction mixture was vigorously shaken at ambient temperature in a 4 mL capped glass vial, using an automatic shaker. A colour change of the solution from light yellow to dark brown took place. After shaking at ambient temperature under TLC monitoring (ethyl acetate/hexane 1:1, R\({}_{f}\): 0.3), complete conversion of **1** into the S-alkylated intermediate was observed after 30 min. Polymer-bound triphenylphosphine (0.54 mmol) (polystyrene, 2% DVB, 3 mmol/g, Fluka) was added in one portion, and the reaction temperature was raised to 80 \({}^{\circ}\)C. Shaking of the suspension was continued for additional 10 h to complete the sulfide contraction reaction. For work-up, the polymer was filtered off and washed with approx. 5 mL of ethyl acetate. The collected filtrates were concentrated under reduced pressure and subjected to flash chromatography (Silica-60, 0.06-0.20 mm, ethyl acetat/hexane 20% vol./vol.) to obtain pure viscous yellow product as an approx. 3:1 inseparable mixture of isomers in 65% (97 mg) yield. HR-MS (ESI-Q-TOF) calcd. for C\({}_{24}\)H\({}_{24}\)N\({}_{3}\)O\({}_{4}\) [MH]\({}^{+}\): 418.1761 found [MH]\({}^{+}\): 418.1769. UV-Vis (CH\({}_{3}\)CN), \(\lambda\) (nm): 374, 282, 244, 193. IR (KBr, cm-1): 2977 (C-H aromatic), 2227 (-C\(\equiv\)N), 1700 (C=O), 1630 (C=C), 1573, 1532, 1509, 1476, 1368, 1328, 1244, 1203, 1172, 1092, 1058, 1031. Raman (powder, ATR, cm-1): 2229, 1649, 1605, 1502, 1382, 1300, 1222, 1177, 1111, 872, 763.