8952
C. M. L. Delpiccolo et al. / Tetrahedron 63 (2007) 8949–8953
CH(CH3)2), 2.72 (t, J¼6.4 Hz, 2H, CH2), 2.32 (s, 3H, p-
CH3), 1.18 (d, J¼6.8 Hz, 6H, C(CH3)2). 13C NMR (CDCl3,
100 MHz) d 180.1 (Cq, C]O), 169.2 (Cq, C]O), 151.9 (Cq,
C]O), 137.3 (Cq, aromatic Cq), 133.8 (Cq, aromatic Cq),
129.0 (CH, aromatic CH), 128.6 (CH, aromatic CH), 43.8
(CH2, PhCH2), 36.9 (CH2, NCH2), 35.3 (CH, CH(CH3)2),
31.8 (CH2, CH2), 21.0 (CH3, p-CH3), 19.5 (2CH3,
CH(CH3)2). MS (ESI); m/z (%): 311 [M+Na] (60), 312
(10), 313 (2), 314 (1). HRMS [M+Na] C16H20N2O3Na: calcd
311.1372; found 311.1366.
138.1 (Cq, aromatic Cq), 134.0 (Cq, aromatic Cq), 129.9
(CH, aromatic CH), 129.5 (CH, aromatic CH), 37.7 (CH2,
NCH2), 35.3 (CH, CH(CH3)2), 32.17 (CH2, CH2), 21.4
(CH3, p-CH3Ph), 20.2 (2CH3, CH(CH3)2). MS (EI+); m/z
(%): 275 [M+1] (20), 274 (100). HRMS [M]+
C15H18N2O3: calcd 274.1317; found 274.1307.
4.1.5. 1-Isobutyryl-3-o-tolyl-dihydropyrimidine-2,4-
dione (2e). Prepared according to general procedure
from 3-(3-o-tolyl-thioureido)-propanoic acid (42.5 mg,
0.18 mmol), isobutyric anhydride (0.90 mL), heating the
mixture for 1 h. The crude product was purified by chroma-
tography (hexane/EtOAc, 75/25) to afford a white solid
(29.4 mg, 60%).
4.1.3. 1-Isobutyryl-5-methyl-3-(4-methylbenzyl)-di-
hydropyrimidine-2,4-dione (2c). Prepared according to
general procedure from 3-[3-(4-methylbenzyl)-thioureido]-
butanoic acid (85 mg, 0.32 mmol), isobutyric anhydride
(1.7 mL), heating the mixture for 2 h. The crude product
was purified by chromatography (hexane/EtOAc, 75/25) to
afford a white solid (51 mg, 53%).
O
O
N
O
N
O
Me
O
N
O
1H NMR (CDCl3, 400 MHz) d 7.35–7.08 (m, 4H, aromatic
H), 4.14–4.10 (m, 2H, NCH2), 3.68–3.62 (m, 1H,
CH(CH3)2), 2.89 (t, J¼6.4 Hz, 2H, CH2), 2.15 (s, 3H,
CH3), 1.20 (d, J¼6.8 Hz, 6H, C(CH3)2). 13C NMR (CDCl3,
100 MHz) d 180.4 (Cq, C]O), 169.3 (Cq, C]O), 151.9 (Cq,
C]O), 135.9 (Cq, aromatic Cq), 134.2 (Cq, aromatic Cq),
131.3 (CH, aromatic CH), 129.6 (CH, aromatic CH), 128.8
(CH, aromatic CH), 127.4 (CH, aromatic CH), 37.6 (CH2,
NCH2), 35.9 (CH, CH(CH3)2), 32.4 (CH2, CH2), 19.9
(2CH3, CH(CH3)2), 17.7 (CH3, CH3). MS (EI+); m/z (%):
274 [M] (100). HRMS [M]+ C15H18N2O3: calcd 274.1317;
found 274.1305.
N
1H NMR (CDCl3, 400 MHz) d 7.27 (d, J¼8 Hz, 2H, aro-
matic H), 7.12 (d, J¼8 Hz, 2H, aromatic H), 4.95 (d, J¼
3.6 Hz, 2H, PhCH2), 4.24 (dd, J¼13.6, 5.2 Hz, 1H, NCHH),
3.74–3.68 (m, 1H, CH(CH3)2), 3.31 (dd, J¼13.6, 10.4 Hz,
1H, NCHH), 2.69–2.64 (m, 1H, CH), 2.32 (s, 3H, p-CH3),
1.28–1.16 (m, 9H, CH3, CH(CH3)2). 13C NMR (CDCl3,
100 MHz) d 180.9 (Cq, COCH(CH3)2), 172.3 (Cq), 152.2
(Cq), 138.0 (Cq, aromatic Cq), 134.1 (Cq, aromatic Cq), 128.7
(CH, aromatic CH), 128.4 (CH, aromatic CH), 44.2 (CH2,
PhCH2), 43.5 (CH2, NCH2), 36.2 (CH, CH), 35.9 (CH,
CH(CH3)2), 21.8 (CH3, p-CH3), 20.0 and 19.9 (CH3,
CH(CH3)2), 13.6 (CH3, CH3). MS (ESI); m/z (%): 325
[M+Na] (320), 326 (50), 327 (10). HRMS [M+Na]
C17H22N2O3Na: calcd 325.1528; found 325.1523.
4.1.6. 1-Isobutyryl-3-(3-methoxy-phenyl)-dihydropyri-
midine-2,4-dione (2f). Prepared according to general
procedure from the 3-[3-(3-methoxy-phenyl)-thioureido]-
propanoic acid (34.8 mg, 0.14 mmol), isobutyric anhydride
(0.70 mL), heating the mixture for 1 h. The crude product
was purified by chromatography (hexane/EtOAc, 75/25) to
afford a white solid (23.8 mg, 60%).
4.1.4. 1-Isobutyryl-3-p-tolyl-dihydropyrimidine-2,4-di-
one (2d). Prepared according to general procedure from 3-
(3-p-tolyl-thioureido)-propanoic acid (92.7 mg, 0.39 mmol),
isobutyric anhydride (2.25 mL), heating the mixture for
0.5 h. The crude product was purified by chromatography
(hexane/EtOAc, 75/25) to afford a white solid (52 mg, 49%).
O
O
N
O
N
OMe
1H NMR (CDCl3, 400 MHz) d 7.41–6.71 (m, 4H, aromatic
H), 4.10 (t, J¼6.4 Hz, 2H, NCH2), 3.81 (s, 3H, OCH3),
3.67–3.60 (m, 1H, CH(CH3)2), 2.88 (t, J¼6.4 Hz, 2H,
CH2), 1.20 (d, J¼6.8 Hz, 6H, C(CH3)2). 13C NMR
(CDCl3, 100 MHz) d 180.4 (Cq, C]O), 169.6 (Cq, C]O),
160.6 (Cq, aromatic Cq), 152.3 (Cq, C]O), 136.1 (Cq, aro-
matic Cq), 130.3 (CH, aromatic CH), 121.0 (CH, aromatic
CH), 114.9 (CH, aromatic CH), 114.7 (CH, aromatic CH),
55.6 (CH3, OCH3), 37.5 (CH2, NCH2), 35.8 (CH,
CH(CH3)2), 32.4 (CH2, CH2), 19.9 (2CH3, (CH3)2). MS
(EI+); m/z (%): 291 [M+1] (42), 290 (100). HRMS [M+]
C15H18N2O4: calcd 290.1267; found 290.1270.
O
O
N
O
N
1H NMR (CDCl3, 400 MHz) d 7.29 (d, J¼8.0 Hz, 2H, aro-
matic H), 7.06 (d, J¼8.0 Hz, 2H, aromatic H), 4.10 (t,
J¼6.4 Hz, 2H, NCH2), 3.68–3.60 (m, 1H, CH(CH3)2),
2.88 (t, J¼6.4 Hz, 2H, CH2), 2.39 (s, 3H, p-CH3Ph), 1.2 (t,
J¼6.4 Hz, 6H, C(CH3)2). 13C NMR (DMSO, 100 MHz)
d 180.2 (Cq, C]O), 170.8 (Cq, C]O), 152.8 (Cq, C]O),