J IRAN CHEM SOC
[eluent: n-hexane: EtOAc (9:2)], the crude product was
filtered off and washed twice with water (2 × 5 mL). The
crude product was purified by recrystallization by ethanol.
General procedure for the preparation of pyrano[2,3‑d]
pyrimidinones
A mixture of aldehyde (1 mmol), barbituric acid (1 mmol),
malononitrile (1.1 mmol), NS-C4(DABCO-SO3H)2·4Cl
(10 mg, 5 mol%) and H2O (5 mL) was heated at 80 °C.
After completion of the reaction as monitored by TLC [elu-
ent: n-hexane: EtOAc (9:2)], the crude product was filtered
off and washed twice with water (2 × 5 mL). The crude
product was purified by recrystallization by ethanol.
Fig. 1 Reusability of the catalyst in the reaction of 4-chlorobenzalde-
hyde, barbituric acid and malononitrile under the optimized reaction
conditions
The spectral data of new compound are presented
below
NS-C4(DABCO-SO3H)2·4Cl, we were interested to investi-
gate the applicability of this reagent in the promotion of the
synthesis of pyrimido[4,5-d]pyrimidinones and pyrano[2,3-
d]pyrimidinones.
7-Amino-5-(2-nitrophenyl)-4-oxo-2-thioxo-1,3,4,5-
tetrahydro-2H-pyrano[2,3-d]pyrimidine-6-carbonitrile
(2 g): M.p. = 242–246 °C; FT-IR (KBr) ν = 3426, 3062,
1
2197, 1675, 1573, 1518, 1349 cm−1; H NMR (400 MHz,
DMSO‑d6): δ = 5.06 (s, 1H), 7.34 (s, 2H), 7.48 (dt,
J1 = 7.6 Hz, J2 = 1.6 Hz, 1H), 7.54 (dd, J1 = 8 Hz,
J2 = 1.2 Hz, 1H), 7.67 (dt, J1 = 7.6 Hz, J2 = 1.2 Hz, 1H),
7.86 (dd, J1 = 8 Hz, J2 = 1.2 Hz, 1H), 12.43 (NH, s, 1H),
13.67 (NH, s, 1H) ppm; 13C NMR (100 MHz, DMSO‑d6):
δ = 30.7, 56.9, 93.4, 119.0, 124.2, 128.6, 131.5, 133.9,
138.0, 149.7, 152.1, 158.6, 160.7, 174.4 ppm.
Experimental
General
The chemical materials were obtained from Merck, Fluka
and Aldrich chemical companies. The TLC was employed
on silica gel polygram SILG/UV 254 plates for purity of
substrate and determination of reaction progress monitor-
ing. Also products were characterized by comparison of
their physical constants such as melting point, color and
spectroscopic data (FT-IR and NMR) with authentic sam-
ples and those reported in the literature.
7-Amino-2,4-dioxo-5-(pyridin-2-yl)-1,3,4,5-tetrahydro-
2H-pyrano[2,3-d]pyrimidine-6-carbonitrile (2o): M.p. =
>300 °C, FT-IR (neat) ν = 3383, 3310, 3183, 2961, 2185,
1
1682, 1649, 1371, 1214, 1148, 1032, 836, 710 cm−1; H
NMR (DMSO-d6, 400 MHz): δ = 4.38 (s, 1H), 7.28 (s, 2H,
NH2), 7.4–8.6 (4H, m, Ar), 9.38 (1H, NH), 11.12 (1H, NH)
ppm; 13C NMR (DMSO-d6, 100 MHz): δ = 26.00, 57.82,
82.82, 115.26, 119.48, 124.93, 136.74, 146.10, 146.68,
147.49, 150.09, 158.31, 159.46, 163.05, 164.58 ppm.
General procedure for the preparation of pyrimido[4,5‑d]
pyrimidinones
The reusability of the NS‑C4(DABCO‑SO3H)2·4Cl
A mixture of aldehyde (1 mmol), barbituric acid (1 mmol),
urea or thiourea (1.1 mmol), NS-C4(DABCO-SO3H)2·4Cl
(15 mg, 7.5 mol%) and H2O (5 mL) was heated at 80 °C.
After completion of the reaction as monitored by TLC
The reusability of the catalyst was checked in the reaction
of 4-chlorobenzaldehyde, barbituric acid and malononitrile
under the optimized reaction conditions. When the reaction
Scheme 1 Synthesis of
pyrimido[4,5-d]pyrimidinones
O
X
O
Ar
Ar
H
H2N
NH2
HN
NH
+
NS-C4(DABCO-SO3H)2).4Cl (15 mg)
H2O, 80 oC
O
O
N
H
N
H
X
HN
1 (a-p)
O
N
H
O
1 3