3-Oxo-N-[4-[4-(3-oxobutanoylamino)phenyl]ethylphenyl]butanamide Gulten, S, SyntheticPages, 2011, 498
Benzaldehyde (Acros Organics)
Thiourea (Acros Organics)
37% HCl (Merck)

A mixture of 3-oxo-N-[4-[4-(3-oxobutanoylamino)phenyl]ethylphenyl]butanamide (300 mg, 0.789 mmol), thiourea (183 mg, 2.41 mmol), benzaldehyde (0.24 mL, 2.41 mmol) and catalytic amount of conc. HCl (4 drops) in EtOH (10 mL) was refluxed overnight. After the completion of reaction, the reaction mixture was allowed to cool. The solid product formed was filtered, washed with water (5 mL) and cold ether (3x5 mL) to remove the unreacted thiourea or benzaldehyde or 3-oxo-N-[4-[4-(3-oxobutanoylamino)phenyl]ethylphenyl]butanamide and dried. The title compound was obtained as a cream coloured solid (450 mg, 88% yield).

This reaction was carried out with catalytic amount of pTSA to give the corresponding bis Biginelli product in good yield.
This reaction was carried out by Elif Özdemir in the  final year research project under my supervision.

IR-ATR:  3377, 3188,  3031, 2969, 2922, 2858, 1672, 1632, 1593, 1515, 1180, 824 cm^-1.
¹H NMR (400 MHz, DMSO-d₆): ppm = 2.06 (s, 6H, CH₃), 2.76 (s, 4H, CH₂), 5.39 (s, 2H, CH) 7.08 (d, 4H, J= 7.8 Hz,  CH_Ar), 7.25-7.40 (m, 10H, CH_Ar), 7.43 (d, 4H, J= 7.8 Hz, CH_Ar), 9.41 (s, 2H, NH), 9.65 (s, 2H, NH), 9.97 (s, 2H, NH).
¹³C NMR (100 MHz, DMSO-d₆): ppm = 174.10, 164.74, 143.04, 136.75, 136.48, 135.23, 128.58, 128.38, 127.63, 126.33, 119.62, 107.29,  55.06, 36.47, 16.45.

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B.R. Prashantha Kumar, Gopu Sankar, R.B. Nasir Baig, Srinivasan Chandrashekaran, Novel  Biginelli dihydropyrimidines with potential anticancer activity: A parallel synthesis and CoMSIA study, Eur. J. Med. Chem., 44, 2009, 4192-4198. doi:10.1016/j.ejmech.2009.05.014