Ghassamipour & Sardarian
obtained using a Shimadzu FT-IR 8300 spectrophotometer.
9.72%. Found: C, 67.00; H, 6.85; N, 9.62%.
Mass spectra were determined on a Shimadzu GCMS-QP
1000 EX instruments at 70 or 20 eV. Melting points were
determined in open capillary tubes in a Büchi-545 circulating
oil melting point apparatus. Materials were purchased from
Fluka, Aldrich and Merck Chemical Companies.
Ethyl 6-methyl-4-(naphthalen-2-yl)-2-oxo-1,2,3,4-tetra-
hydropyrimidine-5-carboxylate (Table 2, Entry 14). Pale-
yellow solid, m.p.: 173-177 °C. IR (KBr): 3224, 3101, 2939,
1
1705, 1651 cm-1. H NMR (250 MHz, DMSO-d6): ꢁ = 1.08
(m, 3H, CH3CH2-), 2.28 (s, 3H, CH3), 3.83 (m, 2H, CH3CH2-),
5.33 (s, 1H, CH-), 7.42-7.48 (m, 3H, arom.), 7.58 (s, 1H, NH),
7.85-7.98 (m, 4H, arom.), 9.25 (s, 1H, NH). 13C NMR (63
MHz, DMSO-d6): ꢁ = 13.89, 17.81, 54.27, 59.13, 98.98,
124.52, 124.84, 125.56, 125.82, 126.20, 127.40, 127.76,
128.26, 132.27, 132.62, 143.20, 148.50, 152.02, 165.29.
EIMS: m/z (%): 311 (19.5, M+1), 310 (M+, 39.1), 309 (42.2),
280 (50.0), 264 (20.5), 237 (49.1), 183 (100.0), 155 (40.6),
127 (33.2), 110 (17.8), 67 (12.4).
5-Benzoyl-6-methyl-4-phenyl-3,4-dihydropyrimidin-2
(1H)-one (Table 2, Entry 16). Yellow solid, m.p.: 173-178
°C. IR (KBr): 3406, 3220, 3105, 2912, 1681, 1654, 1620 cm-1.
1H NMR (250 MHz, DMSO-d6): ꢁ = 2.47 (s, 3H, CH3), 5.07
(s, 1H, CH-), 7.17-7.77 (m, 10H, arom.), 8.09 (s, 1H, NH),
9.15 (s, 1H, NH).13C NMR (63 MHz, DMSO-d6): ꢁ = 18.40,
55.15, 109.40, 126.08, 127.11, 128.40, 128.50, 128.66,
131.38, 140.96, 144.19, 145.29, 152.15, 194.26. EIMS: m/z
(%): 292 (M+, 0.1), 215 (73.7), 187 (51.5), 105 (66.2), 77
(100.0). Anal. Calcd. for C18H16N2O2: C, 73.95; H, 5.52; N,
9.58%. Found: C, 73.78; H, 5.44; N, 9.32%.
4-Phenyl-3,4,7,8-tetrahydroquinazoline-2,5(1H,6H)-
dione (Table 2, Entry 17). Pale-brown solid, m.p.: 226-228.
IR (KBr): 3421, 2920, 1651, 1620 cm-1. 1H NMR (250 MHz,
DMSO-d6): ꢁ = 1.89 (m. 2H, -CH2CH2CH2-), 2.27 (m, 2H,
-COCH2-), 2.57 (m, 2H, -C=C-CH2-), 4.59 (s, 1H, CH-), 7.04-
7.47 (m, 5H, arom.), 8.11 (s, 1H, NH), 9.46 (s, 1H, NH). 13C
NMR (63 MHz, DMSO-d6): ꢁ = 19.80, 26.38, 30.78, 36.33,
115.47, 126.06, 127.90, 128.32, 144.49, 164.78, 193.17.
EIMS: m/z (%): 242 (M+, 2.9), 216 (21.1), 91 (16.3), 71
(25.8), 55 (100.0). Anal. Calcd. for C14H14N2O2: C, 69.42; H,
5.83; N, 11.56%. Found: C, 69.70; H, 6.12; N, 11.65%.
General Procedure for the Biginelli Reaction
Dodecylphosphonic acid (10 mol%) was added to a
mixture of aldehyde (1 mmol), ꢀ-dicarbonyl compound (1
mmol) and urea or thiourea (1.5 mmol). The neat reaction
mixture was heated with stirring for appropriate time at 70 ºC.
The resulting powder was dissolved in hot ethanol. Then, the
solution was poured onto crushed ice. The separated solid was
filtered and recrystallized from hot ethanol to afford pure
product.
Typical Spectral Data
Ethyl
6-methyl-2-oxo-4-(pyridin-3-yl)-1,2,3,4-tetra-
hydropyrimidine-5-carboxylate (Table 2, Entry 9). Brick
red solid, m.p.: 205-207 °C. IR (KBr): 3348, 3112, 2977,
1
1693, 1643 cm-1. H NMR (250 MHz, DMSO-d6): ꢁ = 1.05
(m, 3H, CH3CH2-), 2.24 (s, 3H, CH3), 3.92 (m, 2H, CH3CH2-),
5.16 (s, 1H, CH-), 7.35 (m, 1H, arom.), 7.60 (m, 1H, arom.),
7.78 (s, 1H, NH), 8.42 (2H, arom.), 9.28 (s, 1H, NH). 13C
NMR (63 MHz, DMSO-d6): ꢁ = 13.95, 17.72, 52.06, 59.25,
98.28, 123.73, 133.88, 140.03, 147.81, 148.49, 149.05,
151.80, 165.01. EIMS: m/z (%): 261 (M+, 8.4), 232 (45.4), 183
(100.0), 155 (61.8), 137 (54.6), 110 (19.3), 83 (39.5), 57
(84.9). Anal. Calcd. for C13H15N3O3: C, 59.74; H, 5.74; N,
16.08%. Found: C, 59.45; H, 5.80; N, 15.87%.
Ethyl 6-methyl-2-oxo-4-phenethyl-1,2,3,4-tetrahydro-
pyrimidine-5-carboxylate (Table 2, Entry 10). White solid,
m.p.: 149-152 °C. IR (KBr): 3247, 3116, 2931, 1705, 1651
cm-1. 1H NMR (250 MHz, CDCl3): ꢁ = 1.21 (m, 3H, CH3CH2-
), 1.87 (m, 2H, PhCH2CH2-), 2.28 (s, 3H, CH3), 2.69 (m, 2H,
PhCH2CH2-), 4.12 (m, 2H, CH3CH2-), 4.33 (m, 1H, CH-), 5.83
(s, 1H, NH), 7.03-7.30 (m, 5H, arom.), 7.94 (s, 1H, NH). 13C
NMR (63 MHz, CDCl3): ꢁ = 14.29, 18.59, 30.68, 36.89, 38.14,
51.095, 59.93, 101.38, 125.99, 128.05, 128.29, 128.46,
141.00, 146.97, 154.25, 165.69. EIMS: m/z (%): 288 (M+,
0.2), 243 (2.7), 200 (0.4), 183 (100.0), 155 (34.8), 137 (26.8),
91 (20.1). Anal. Calcd. for C16H20N2O3: C, 66.65; H, 6.99; N,
RESULTS AND DISCUSSION
During preliminary studies, the condensation of 2-
chlorobenzaldehyde, ethyl acetoacetate, and urea was utilized
as the model for finding the optimization conditions (Scheme
1). We can observe that a trace of product (25%) could be
238