Multilinker phosphorous acid anchored En/MIL-100(Cr) as a novel nanoporous catalyst for the synthesis of new N-heterocyclic pyrimido[4,5-b]quinolines

Article abstract of DOI:10.1016/j.mcat.2019.01.023

A novel ethylenediamine (En) based metal-organic frameworks (MOFs) of Cr-MOFs, En/MIL-100(Cr), containing phosphorous acid tags was prepared. MIL-100(Cr)/NHEtN(CH₂PO₃H₂)₂ characterized by a variety of techniques

Full text of DOI:10.1016/j.mcat.2019.01.023

MolecularCatalysisxxx(xxxx)xxx–xxx
Contents lists available at ScienceDirect
Molecular Catalysis
journal homepage: www.elsevier.com/locate/mcat
Editor’s choice paper
Multilinker phosphorous acid anchored En/MIL-100(Cr) as a novel
nanoporous catalyst for the synthesis of new N-heterocyclic pyrimido[4,5-b]
quinolines
⁎
⁎
Hassan Sepehrmansouria, Mahmoud Zareia, , Mohammad Ali Zolfigola,
,
⁎
⁎
Ahmad Reza Moosavi-Zareb, , Sadegh Rostamniac, , Saeid Moradia
a Department of Organic Chemistry, Faculty of Chemistry, Bu-Ali Sina University, Hamedan 6517838683, Iran
b Sayyed Jamaleddin Asadabadi University, Asadabad, 6541861841, Iran
c Organic and Nano Group (ONG), Department of Chemistry, Faculty of Science, University of Maragheh, PO Box 55181-83111, Maragheh, Iran
A R T I C L E I N F O
A B S T R A C T
Keywords:
A novel ethylenediamine (En) based metal-organic frameworks (MOFs) of Cr-MOFs, En/MIL-100(Cr), containing
phosphorous acid tags was prepared. MIL-100(Cr)/NHEtN(CH2PO3H2)2 characterized by a variety of techniques,
including fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), elemental
mapping and energy dispersive X-ray (EDS), transmission electron microscopy (TEM), Thermal gravimetric (TG),
differential thermal gravimetric (DTG), N2 adsorption-desorption isotherms (BET) and elemental analysis. MIL-
100(Cr)/NHEtN(CH2PO3H2)2 successfully applied for the synthesis of new categories of N-heterocyclic com-
pounds such as tetrahydropyrimido[4,5-b]quinoline-2,4,6(1H,3H,7H)-trione, tetrahydropyrimido[4,5-b]quino-
line-4,6(3H,7H)-dione and octahydropyrimido[4,5-b]quinolin-6(1H)-one derivatives. More specifically, this
paper has explored new tetrahydropyrimido[4,5-b]quinolone based on uracil (X = S, O). The major advantages
of this work are high yields, short reaction times, high stability thermal, facile workup and reusability of the
MOFs catalyst.
En/MIL-100(Cr)
MIL (Matérial Institut Lavoisier)
Metal-organic frameworks (MOFs)
Multilinker phosphorous acid catalyst
Octahydropyrimido[4,5-b]quinoline-6(1H)-one
Tetrahydropyrimido[4,5-b]quinolone
Tetrahydropyrimido[4,5-b]quinoline-
4,6(3H,7H)-dione
1. Introduction
organic linker groups for target reactions with biological molecules
builds them appealing to motivation enzymes for catalytic processes.
Nowadays, solid compounds with crystalline structure were pre-
pared by inorganic clusters or metal ions (generally transition metal)
which linked to two or multifunctional organic units to give metal-or-
ganic frameworks (MOFs) [1]. In recent years, Metal-organic frame-
works (MOFs) are valuable materials because of their applications on
the preparation of various catalysts, sensors, electronics, fuel cells and
industrial products in large scale and other applications of them in
adsorption, petrochemistry, selective separation, and drug delivery
[2–4].
Therefore, nanoarchitecture with the goal apply changes in surface
area, pore size, stability thermal and chemical improve the performance
of the structure of metal-organic frameworks (MOFs) [9]. The catalytic
activities of MOFs were also reported in cases of oxidation reactions,
CeC bond formation and organic synthesis [10–11]. Recently, the fa-
cility of the design and modification of MOFs, as a significant system,
have developed to produce new functionalized frameworks for other
applications [12–15]. The synthesis of MIL-100(Cr) was reported by
Férey et al. for the first time [16]. Some MOFs such as [MoO(O2)2@En/
MIL-100(Cr)], Pd@En/MIL-100(Cr) and MIL-100(Cr)One, as a category
of metal-organic frameworks (MOFs) containing of Cr nuclei, has post-
modification ability and increases the flexibility and compatibility of
the compound and can be used as bifunctional catalysts for the oxida-
tion of selective thioether, Knoevenagel condensation reaction, Friedel-
Crafts reaction, Aldol condensation, coupling reaction, ring opening of
epoxides, 1,3-Dipolar cycloaddition, multicomponent reactions (MCRs)
Some advantages of nanoscopic materials and porous materials are
high surface area, high thermal stability of their chemical structure [5].
Multivariate MOFs (MTV-MOFs), in which numerous nuclei, organic
and linker features are merged into a framework, have introduced with
many chances for modeling the complexity of the porous of MOFs in a
logical method [6–8]. Among the many developments which made in
this field and nanoscale properties of MOFs can be modified with
⁎ Corresponding authors.
E-mail addresses: mahmoud8103@yahoo.com (M. Zarei), zolfi@basu.ac.ir (M.A. Zolfigol), moosavizare@yahoo.com (A.R. Moosavi-Zare),
srostamnia@gmail.com (S. Rostamnia).
https://doi.org/10.1016/j.mcat.2019.01.023
Received 14 October 2018; Received in revised form 28 December 2018; Accepted 22 January 2019
2468-8231/©2019ElsevierB.V.Allrightsreserved.
Pleasecitethisarticleas:Sepehrmansouri,H.,MolecularCatalysis,https://doi.org/10.1016/j.mcat.2019.01.023

H. Sepehrmansouri et al.
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and CO2 adsorption respectively [17–20].
apparatus in open capillary tubes. Fourier transforms infrared (FT-IR)
spectra of derivatives and catalyst were recorded on a FT-IR spectro-
meter (Perkin-Elmer spectrum 65) using KBr disk. Transmission elec-
tron microscopy (TEM) images were performed using a Zeiss-EM10C-
100 microscope. Scanning electron microscopy (SEM), SEM-EDS ele-
mental mapping studies were performed using a SIGMA VP-500.
Thermogravimetric analyses were carried out on a METTLER TOLEDO
apparatus (models Pyris 1) under nitrogen atmosphere at 25 °C and
using a heating rate of 20 °C min−1 up to 550 °C. Nitrogen adsorption-
desorption isotherm (BET) was performed using a BELSORP MINI II.
Multi component reactions (MCRs) are one of the most important
methods for the synthesis of products in organic and medicinal chem-
istry. At first, the synthesis of amino acids was reported as a multi
component reaction, by Strecker in 1850 [21]. In last few years, MCRs
were developed in three, four or more component reactions and re-
ported so many researches for developing of new MCRs [22]. It is ne-
cessary to reduce toxic waste and time of reaction process in industrials
and experimental studies for environmental protection. Furthermore,
high yield in the synthesis of products is remarkable.
N-Heterocyclic compounds such as uracil derivatives are one of the
important categories of compounds in organic synthesis. Quinoline and
pyrimidines derivatives containing uracil in their structure are inter-
esting classes of organic compounds because of their pharmacological
activity including antitumour [23], cardiotonic [24], hepatoprotactive
[24], antihypertensive [24], antibronchitic [25] and antifungal activity
[26]. Pyrimido[4,5-b]quinolone derivatives are a category of fused
quinolines which separated from the marine bacteria having anti-
bacterial and antifungal activities. There is extensive information about
synthesis of these biological molecules for the synthesis of uracil-based
derivatives [27–31]. In the present research, we have explored MOFs
chemically modified by organophosphonic acid MIL-100(Cr)/NHEtN
(CH2PO3H2)2 based on En/MIL-100(Cr) by heterogeneous synthesis
method, and used it as task-specific and reusable catalyst for the op-
erational and one-pot synthetic method of new N-heterocyclic com-
pounds such as tetrahydropyrimido[4,5-b]quinoline-2,4,6(1H,3H,7H)-
trione, tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7H)-dione and oc-
tahydropyrimido[4,5-b]quinolin-6(1H)-one derivatives (Scheme 1).
2.2. Preparation of MIL-100(Cr)
According to previous reports [17], In a teflon-lined stainless steel
autoclave, a mixture of chromium trioxide (12 mmol, 1.2 g), ter-
ephthalic acid (11.99 mmol, 1.99 g), hydrofluoric acid (12 mmol) (HF,
40%) and deionized water 58 mL were mixed and stirred at 25 °C
during two hours and then kept at 220 °C for four days. The obtained
green solid was washed with water and dried at room temperature.
2.3. Grafting ethylenediamine onto the MIL-100(Cr) [En/MIL-100(Cr)]
After synthesis of MOFs, 0.1 g of MIL-100(Cr), activated at 200 °C
for 2 h. Then it was suspended in 10 mL of ultra-dry toluene and 1 mL of
ethylene diamine was added to this suspension, and the mixture was
stirred under argon atmosphere of for 16 h to facilitate amine grafting.
The resulting En/MIL-100(Cr) solid was collected by filtration and
washed with acetone for several times [17].
2. Experimental
2.1. Instrumental details
2.4. Preparation of MIL-100(Cr)/NHEtN(CH2PO3H2)2
All of chemicals were prepared from Merck Chemical Company. The
known products were identified by comparison of their melting points
and spectral data with those reported in the literature. Progress of the
reactions was monitored by TLC using silica gel SIL G/UV 254 plates.
The 1H NMR (400 MHz) and 13C NMR (100 MHz) were run on a
BRUKER BioSpin GmbH or Bruker Avance DPX-250 FT-NMR spectro-
meter (δ in ppm). Melting points were recorded on a Büchi B-545
In a 100 mL round-bottomed flask, a mixture of En/MIL-100(Cr)
[MIL-100(Cr)/NHEtNH2] (1 g), paraformaldehyde (28 mmol, 0.840 g),
phosphorous acid (28 mmol, 2.296 g), HCl (2 ml, 37%) and 50 ml of
ethanol was refluxed for 18 h [32]. After this time, a green precipitated
appeared which was filtered and dried under vacuum to obtain MIL-
100(Cr)/NHEtN(CH2PO3H2)2 (Scheme 2).
Scheme 1. Synthesis of N-heterocyclic compounds catalyzed by MIL-100(Cr)/NHEtN(CH2PO3H2)2.
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Scheme 2. Preparation of MIL-100(Cr)/NHEtN(CH2PO3H2)2.
Scheme 3. Synthesis of pyrimido[4,5-b]quinolone derivatives using MIL-100(Cr)/NHEtN(CH2PO3H2)2.
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Fig. 1. FT-IR spectrum of a) MIL-100(Cr)/NHEtNH2 b) MIL-100(Cr)/NHEtN(CH2PO3H2)2.
2.5. General procedure for the preparation of pyrimido[4,5-b]quinolone
derivatives
2 H), 7.42 (d, J = 8.3 Hz, 2 H), 6.46 (s, 2 H), 4.92 (s, 1 H), 2.53- 2.44
(m, 2 H), 2.25 (d, J = 16.1 Hz, 1 H), 2.06 (d, J = 16.1 Hz, 1 H), 1.08 (s,
3 H), 0.95 (s, 3 H); 13C NMR (100 MHz, DMSO-d6): δ (ppm): 193.78,
161.43, 157.06, 153.75, 151.01, 139.95, 128.26, 112.87, 109.92,
92.38, 54.84, 50.22, 32.45, 32.04, 29.07, 26.70, 18.54. MS m/z (%);
found for C20H19N5O2: 361.4.
In a 10 mL round-bottomed flask, a mixture of aldehyde (1 mmol),
uracil derivatives (1 mmol), dimedone (1 mmol, 0.14 g) and MIL-
100(Cr)/NHEtN(CH2PO3H2)2 (0.01 g) were stirred at 100 °C in DMF
(5 ml) as solvent. After completion of the reaction as monitored by TLC,
the reaction mixture was cooled to room temperature. Then, the cata-
lyst was separated from the solution of reaction mixture by cen-
trifugation (1000 rpm). Then, H2O (5 ml) was added to reaction mixture
to give the solid sediment. The prepared solid was collected by simple
filtration. The crude product was purified by recrystallization from
2.5.2. 2-Amino-5-(furan-2-yl)-8,8-dimethyl-5,8,9,10-tetrahydropyrimido
[4,5-b]quinoline-4,6(3H,7 H)-dione (2S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1)= 0.8; IR
(KBr, cm−1): 3480, 3249, 3045, 2886, 1665, 1620; 1H NMR (400 MHz,
DMSO-d6): δ (ppm):10.44 (s, 2 H), 9.41 (s, 2 H), 7.20 (dt, J = 10.5,
8.5 Hz, 3 H), 7.08 (ddd, J = 11.6, 8.0, 1.8 Hz, 3 H), 6.99-6.87 (m, 3 H),
6.38 (s, 2 H), 4.78 (s, 3 H), 2.46- 2.33 (m, 2 H), 2.15 (d, J = 16.1 Hz,
1 H), 1.99 (d, J = 16.0 Hz, 1 H), 0.98 (s, 3 H), 0.87 (s, 3 H); 13C NMR
(100 MHz, DMSO-d6): δ (ppm): 193.9, 161.4, 154.1, 153.9, 153.8,
151.7, 151.6, 149.9, 149.8, 148.7, 148.5, 147.5, 147.4, 146.2, 146.1,
145.1, 123.6, 123.6, 123.6, 123.5, 116.5, 116.4, 116.0, 115.9, 108.9,
108.8, 91.2, 91.2, 50.0, 33.2, 32.0, 28.8, 26.7. MS m/z (%); found for
EtOAc (Scheme 3). The pure products were identified by FT-IR, 1H, 13
NMR and mass spectra.
C
2.5.1. 4-(2-Amino-8,8-dimethyl-4,6-dioxo-3,4,5,6,7,8,9,10-
octahydropyrimido[4,5-b]quinolin-5-yl)benzonitrile (1S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.6; IR
(KBr, cm−1): 3436, 3244, 2931, 2230, 1692, 1651; 1H NMR (400 MHz,
DMSO-d6): δ (ppm):10.49 (s, 1 H), 9.52 (s, 1 H), 7.72 (d, J = 8.3 Hz,
C17H18N4O3: 326.3.
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Fig. 2. Elemental maps (EDX) of C (green, a); N (orange, b); Cr (blue, c); P (yellow, d) and O (violet, e) atoms for MIL-100(Cr)/NHEtN(CH2PO3H2)2. SEM-EDS
analysis f) MIL-100(Cr)/NHEtN(CH2PO3H2)2 g) MIL-100(Cr)/NHEtNH2 (For interpretation of the references to colour in this figure legend, the reader is referred to
the web version of this article).
2.5.3. 2-Amino-5-(dimethylamino)phenyl)-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (3S)
J = 17.2 Hz, 1 H), 2.36 (d, J = 17.2 Hz, 1 H), 2.16 (d, J = 16.1 Hz,
1 H), 1.97 (d, J = 16.0 Hz, 1 H), 1.00 (s, 3 H), 0.91 (s, 3 H); 13C NMR
(100 MHz, DMSO-d6): δ (ppm):193.8, 161.4, 153.7, 153.6, 150.7,
148.5, 136.1, 127.8, 112.0, 110.1, 92.7, 50.2, 32.1, 32.0, 29.1, 26.7.
MS m/z (%); found for C21H25N5O2: 379.4.
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1): 0.8; IR (KBr,
cm−1): 3420, 3249, 3188, 2932, 2607, 1671, 1614; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.34 (s, 1 H), 9.24 (s, 1 H), 6.99 (d, J = 8.6 Hz,
2 H), 6.53 (d, J = 8.7 Hz, 2 H), 6.28 (s, 2 H), 4.70 (s, 1 H), 2.43 (d,
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Fig. 3. SEM of MIL-100(Cr)/NHEtN(CH2PO3H2)2.
2.5.4. 2-Amino-5-(3,5-difluorophenyl)-8,8-dimethyl-5,8,9,10-
DMSO-d6): δ (ppm): 9.48 (s, 1 H), 8.01 (d, J = 8.3 Hz, 1 H), 7.89 (d,
J = 7.9 Hz, 1 H), 7.78 (d, J = 8.8 Hz, 1 H), 7.50 (t, J = 7.3 Hz, 1 H),
7.43 (t, J = 7.3 Hz, 1 H), 7.27 (d, J = 8.8 Hz, 1 H), 6.27 (s, 1 H), 6.05 (s,
1 H), 5.09 (s, 1 H), 2.73-2.59 (m, 2 H), 2.39 (d, J = 16.3 Hz, 1 H), 2.23
(d, J = 16.3 Hz, 1 H), 1.13 (s, 3 H), 1.04 (s, 3 H); 13C NMR (100 MHz,
DMSO-d6): δ (ppm):197.5, 164.9, 160.9, 148.1, 131.44, 130.5, 128.2,
127.3, 126.3, 124.1, 123.4, 117.2, 116.6, 110.3, 93.0, 50.2, 31.8, 29.0,
26.2, 25.3. MS m/z (%); found for C23H22N4O3: 402.2.
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (4S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.65; IR
(KBr, cm−1): 3487, 3356, 3273, 2963, 2893, 1664; 1625; 1H NMR
(400 MHz, DMSO-d6): δ (ppm):10.55 (s, 1 H), 9.61 (s, 1 H), 7.90 (s,
1 H), 7.80 (s, 2 H), 6.55 (s, 2 H), 4.99 (s, 1 H), 2.60 (s, 1 H), 2.48 (d,
J = 17.3 Hz, 1 H), 2.28 (d, J = 16.1 Hz, 1 H), 2.03 (d, J = 16.1 Hz,
1 H), 1.08 (s, 3 H), 0.94 (s, 3 H); 13C NMR (100 MHz, DMSO-d6): δ
(ppm): 193.9, 161.4, 154.3, 153.9, 153.8, 152.5, 152.4, 150.5, 129.6,
129.3, 128.9, 127.7, 127.4, 124.7, 122.0, 119.4, 108.1, 108.1, 90.6,
90.6, 49.8, 34.5, 32.0, 29.2, 25.9. MS m/z (%); found for
2.5.6. 2-Amino-5-(3,5-dimethoxyphenyl)-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (6S)
C
19H18Cl2N4O2: 405.2.
White solid; Mp: > 350 °C; (n-hexane: acetone 1:1) = 0.6; IR (KBr,
cm−1): 3572, 3447, 3272, 2934, 1656, 1620; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.40 (s, 1 H), 9.31 (s, 1 H), 6.83 (d, J = 1.8 Hz,
1 H), 6.74 (d, J = 8.3 Hz, 1 H), 6.63 (dd, J = 8.3, 1.8 Hz, 1 H), 6.33 (s,
2 H), 4.76 (s, 1 H), 3.66 (s, 3 H), 3.65 (s, 3 H), 2.45 (d, J = 17.2 Hz,
1 H), 2.38 (d, J = 17.2 Hz, 1 H), 2.18 (d, J = 16.1 Hz, 1 H), 1.99 (d,
2.5.5. 2-Amino-5-(2-hydroxynaphthalen-1-yl)-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (5S)
White solid; Mp: 280–282 °C; (n-hexane: acetone 1:1) = 0.6; IR
(KBr, cm−1): 3396, 3317, 3191, 2926, 2874, 1644; 1H NMR (400 MHz,
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Fig. 4. TEM images of MIL-100(Cr)/NHEtN(CH2PO3H2)2.
Fig. 6. N2 adsorption/desorption isotherm of En/MIL-100(Cr) and MIL-
100(Cr)/NHEtN(CH2PO3H2)2.
Fig. 5. The thermogravimetric (TG), derivative thermogravimetric (DTG), as
well as the differential thermal (DTA) analysis of MIL-100(Cr)/NHEtN
(CH2PO3H2)2.
DMSO-d6): δ (ppm): 10.26 (s, 1 H), 9.37 (s, 1 H), 7.27 (dd, J = 7.7,
1.5 Hz, 1 H), 7.18 (dd, J = 7.9, 1.0 Hz, 1 H), 7.13 (td, J = 7.5, 1.1 Hz,
1 H), 7.04 (td, J = 7.6, 1.6 Hz, 1 H), 6.32 (s, 2 H), 5.10 (s, 1 H), 2.44 (d,
J = 17.1 Hz, 1 H), 2.33 (d, J = 17.1 Hz, 1 H), 2.13 (d, J = 16.1 Hz,
1 H), 1.90 (d, J = 16.1 Hz, 1 H), 0.99 (s, 3 H), 0.87 (s, 3 H);13C NMR
(100 MHz, DMSO-d6): δ (ppm): 193.5, 161.1, 154.0, 153.9, 151.5,
151.4, 144.6, 132.3, 131.8, 128.8, 126.7, 126.1, 108.9, 91.4, 50.1,
33.5, 31.8, 29.1, 26.4. MS m/z (%); found for C19H19ClN4O2: 370.8.
J = 16.0 Hz, 1 H), 1.01 (s, 3 H), 0.93 (s, 3 H); 13C NMR (100 MHz,
DMSO-d6): δ (ppm): 193.9, 161.5, 153.8, 153.7, 153.6, 151.2, 151.1,
147.8, 146.7, 140.3, 119.0, 111.7, 111.2, 109.7, 109.6, 92.2, 92.2,
55.4, 55.2, 50.2, 40.3, 32.6, 32.0, 29.1, 26.5. MS m/z (%); found for
C
21H24N4O4: 396.4.
2.5.7. 2-Amino-8,8-dimethyl-5-phenyl-5,8,9,10-tetrahydropyrimido[4,5-
b]quinoline-4,6(3H,7 H)-dione (7S)
2.5.9. 2-Amino-8,8-dimethyl-5-(4-nitrophenyl)-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (9S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.4; IR
(KBr, cm−1): 3437, 3244, 3029, 2967, 1623, 1590; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.46 (s, 1 H), 9.41 (s, 1 H), 7.29- 7.18 (m, 4 H),
7.15- 7.04 (m, 1 H), 6.41 (s, 2 H), 4.88 (s, 1 H), 2.53 (d, J = 17.2 Hz,
1 H), 2.45 (d, J = 17.2 Hz, 1 H), 2.24 (d, J = 16.1 Hz, 1 H), 2.05 (d,
J = 16.1 Hz, 1 H), 1.08 (s, 3 H), 0.96 (s, 3 H); 13C NMR (100 MHz,
DMSO-d6): δ (ppm): 193.8, 161.4, 153.9, 153.8, 151.3, 151.2, 147.5,
131.5, 128.64, 127.5, 127.4, 125.3, 109.6, 92.0, 65.0, 50.1, 33.3, 32.0,
29.9, 29.0, 26.6, 18.6, 13.5. MS m/z (%); found for C19H20N4O2: 336.4.
Yellow solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.7; IR
(KBr, cm−1): 3470, 3336, 3257, 3194, 1665, 1618, 1517, 1348; 1H
NMR (400 MHz, DMSO-d6): δ (ppm): 10.46 (s, 1 H), 9.49 (s, 1 H), 8.08
(d, J = 8.7 Hz, 2 H), 7.43 (d, J = 8.7 Hz, 2 H), 6.41 (s, 2 H), 4.91 (s,
1 H), 2.46 (s, 1 H), 2.40 (d, J = 17.2 Hz, 1 H), 2.18 (d, J = 16.1 Hz,
1 H), 1.98 (d, J = 16.1 Hz, 1 H), 1.00 (s, 3 H), 0.88 (s, 3 H);13C NMR
(100 MHz, DMSO-d6): δ (ppm): 193.8, 161.3, 155.1, 154.2, 154.0,
153.96, 152.0, 151.9, 145.3, 128.6, 122.9, 108.6, 108.5, 90.9, 90.8,
50.0, 34.4, 32.0, 28.9, 26.7. MS m/z (%); found for C19H19N5O4: 381.3.
2.5.8. 2-Amino-5-(2-chlorophenyl)-8,8-dimethyl-5,8,9,10-
2.5.10. 2-Amino-8,8-dimethyl-5-(thiophen-2-yl)-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dion (8S)
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (10S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.8; IR
(KBr, cm−1): 3322, 3163, 2971, 1717, 1640;1H NMR (400 MHz, DMSO-
White solid; Mp: 270–272 °C; Rf: (n-hexane: acetone 1:1) = 0.7; IR
(KBr, cm−1): 3621, 3164, 3466, 3422, 2872, 1657; 1H NMR (400 MHz,
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Table 1
Effect of different amounts of catalyst, temperature and solvent on the synthesis of 2-amino-5-(4-chlorophenyl)-
8,8-dimethyl-5,8,9,10-tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7H)-dione.
Entry
Solvent
Catalyst (g)
Temp. (˚C)
Time (min)
Yielda (%)
1
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
H2O
0.02
0.01
0.01
0.01
0.01
0.01
0.005
–
100
20
80
20
35
50
85
70
35
–
2
25
120
90
3
50
4
80
90
5
100
15
6
Reflux
100
300
300
300
120
300
300
300
300
300
300
120
7
8
Reflux
100
9
0.02
0.01
0.01
0.01
0.01
0.01
0.01
0.01
50
10
15
–
10
11
12
13
14
15
16
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
100
EtOH
CH2Cl2
CHCl3
EtOAc
CH3CN
–
–
15
–
–
a
Reaction conditions: 2,6-diamino pyrimidin-4(3H)-one(1 mmol, 0.126 g), 4-chloro benzaldehyde (1 mmol,
0.14 g) and dimedone (1 mmol, 0.14 g).
d6): δ (ppm): 10.54 (s, 1 H), 9.53 (s, 1 H), 7.00 (tt, J = 9.2, 2.3 Hz, 1 H),
6.86 (dd, J = 8.5, 2.0 Hz, 2 H), 6.38 (d, J = 89.5 Hz, 2 H), 4.92 (s, 1 H),
2.52 (s, 2 H), 2.26 (d, J = 16.1 Hz, 1 H), 2.12 (d, J = 16.1 Hz, 1 H),
1.14- 1.04 (m, 3 H), 1.04- 0.93 (m, 3 H); 13C NMR (100 MHz, DMSO-d6):
δ (ppm): 193.9, 163.1, 163.0, 161.4, 160.7, 160.6, 154.2, 154.0, 152.1,
110.2, 110.0, 108.4, 90.8, 50.0, 33.7, 32.0, 28.8, 26.7. MS m/z (%);
found for C17H18N4O2S: 342.4.
(KBr, cm−1): 3276, 3193, 3088, 1720, 1669, 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.38 (s, 1 H), 9.24 (s, 1 H), 9.00 (s, 1 H), 6.95 (d,
J = 6.6 Hz, 2 H), 6.53 (d, J = 6.8 Hz, 2 H), 6.30 (s, 2 H), 4.70 (s, 1 H),
2.43 (d, J = 17.4 Hz, 1 H), 2.36 (d, J = 17.3 Hz, 1 H), 2.15 (d,
J = 16.1 Hz, 1 H), 1.97 (d, J = 16.0 Hz, 1 H), 1.00 (s, 3 H), 0.89 (s,
3 H); 13C NMR (100 MHz, DMSO-d6): δ (ppm): 193.8, 155.0, 153.7,
150.88, 150.7, 138.3, 128.2, 114.1, 114.1, 110.1, 92.5, 50.2, 32.2,
32.0, 29.0, 26.6. MS m/z (%); found for C19H20N4O3: 352.3.
2.5.11. 2-Amino-8,8-dimethyl-5-(p-tolyl)-5,8,9,10-tetrahydropyrimido
[4,5-b]quinoline-4,6(3H,7 H)-dione (11S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.5; IR
(KBr, cm−1): 3472, 3257, 2931, 2748, 1659, 1620; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.39 (s, 1 H), 9.32 (s, 1 H), 7.07 (d, J = 8.0 Hz,
2 H), 6.97 (d, J = 7.9 Hz, 2 H), 6.34 (s, 2 H), 4.78 (s, 1 H), 2.46 (d,
J = 17.1 Hz, 1 H), 2.38 (d, J = 17.4 Hz, 1 H), 2.20 (s, 3 H), 2.16 (s, 1 H),
1.98 (d, J = 16.0 Hz, 1 H), 1.02 (s, 3 H), 0.91 (s, 3 H); 13C NMR
(100 MHz, DMSO-d6): δ (ppm): 193.8, 161.4, 153.8, 153.8, 151.1,
144.7, 134.1, 128.0, 127.3, 109.8, 109.8, 92.2, 50.1, 32.9, 32.0, 29.0,
26.6, 20.5.MS m/z (%); found for C20H22N4O2: 350.4.
2.5.14. 2-Amino-5-(4-methoxyphenyl)-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (14S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.6; IR
(KBr, cm−1): 3404, 3250, 3194, 2937, 1657; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.43 (s, 1 H), 9.36 (s, 1 H), 7.15 (d, 2 H), 6.80 (d,
2 H), 6.37 (s, 2 H), 4.82 (s, 1 H), 3.75 (s, 3 H), 2.52 (d, J = 17.3 Hz,
1 H), 2.45 (d, J = 17.3 Hz, 1 H), 2.24 (d, J = 16.1 Hz, 1 H), 2.06 (d,
J = 16.1 Hz, 1 H), 1.09 (s, 3 H), 0.98 (s, 3 H); 13C NMR (100 MHz,
DMSO-d6): δ (ppm): 193.7, 161.4, 157.0, 153.8, 153.7, 151.0, 150.8,
139.9, 128.2, 112.8, 109.9, 92.3, 77.5, 54.8, 50.2, 32.45, 32.0, 29.0,
26.7, 18.5. MS m/z (%); found for C20H22N4O3: 366.4.
2.5.12. 2-Amino-5-(4-chlorophenyl)-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (12S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.6; IR
(KBr, cm−1): 3399, 3257, 3170, 2967, 1641, 1621; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.41 (s, 1H, NH), 9.37 (s, 1H, NH), 7.20 (q,
J = 8.5 Hz, 4 H), 6.35 (s, 2H, NH2), 4.79 (s, 1 H), 2.45 (d, J = 17.2 Hz,
1 H), 2.38 (d, J = 17.2 Hz, 1 H), 2.17 (d, J = 16.1 Hz, 1 H), 1.98 (d,
J = 16.1 Hz, 1 H), 1.00 (s, 3 H), 0.88 (s, 3 H); 13C NMR (100 MHz,
DMSO-d6): δ (ppm): 193.8, 161.3, 154.0, 153.9, 153.8, 151.5, 151.3,
146.5, 129.8, 129.2, 127.4, 109.2, 109.2, 91.6, 91.6, 50.1, 33.2, 32.0,
28.9, 26.6. MS m/z (%); found for C19H19ClN4O2: 370.8.
2.5.15. 2-Amino-5-(3,4-dimethoxyphenyl)-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (15S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.7; IR
(KBr, cm−1): 3426, 3269, 3176, 2957, 1670, 1638; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.42 (s, 1 H), 9.35 (s, 1 H), 6.89 (d, J = 1.9 Hz,
1 H), 6.80 (d, J = 8.3 Hz, 1 H), 6.69 (dd, J = 8.3, 1.9 Hz, 1 H), 6.36 (s,
2 H), 4.82 (s, 1 H), 3.72 (s, 3 H), 3.71 (s, 3 H), 2.52 (d, J = 17.2 Hz,
1 H), 2.47- 2.38 (m, 1 H), 2.24 (d, J = 16.0 Hz, 1 H), 2.06 (d,
J = 16.0 Hz, 1 H), 1.07 (s, 3 H), 0.99 (s, 3 H); 13C NMR (100 MHz,
DMSO-d6): δ (ppm): 193.8, 161.5, 153.8, 153.7, 151.2, 147.8, 146.7,
140.3, 119.0, 111.7, 111.2, 109.6, 92.2, 55.4, 55.2, 50.2, 32.6, 32.0,
29.1, 26.6. MS m/z (%); found for C21H24N4O4: 396.4.
2.5.13. 2-Amino-5-(4-hydroxyphenyl)-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (13S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.45; IR
8

H. Sepehrmansouri et al.
MolecularCatalysisxxx(xxxx)xxx–xxx
Table 2
Synthesis of N-heterocyclic compounds in DMF at 100 °C.
Entry
Uracil
Product
Time (min)
15
Yield (%)
88
M.p (˚C)
> 350
1
2
3
15
20
76
84
> 350
> 350
4
5
15
15
82
79
> 350
280-282
6
15
88
> 350
7
8
15
15
85
87
> 350
270-272
9
15
91
> 350
(continued on next page)
9

H. Sepehrmansouri et al.
MolecularCatalysisxxx(xxxx)xxx–xxx
Table 2 (continued)
Entry
10
Uracil
Product
Time (min)
15
Yield (%)
78
M.p (˚C)
> 350
11
12
13
14
15
15
15
15
84
90
83
90
> 350
> 350
> 350
> 350
15
16
20
20
84
86
> 350
> 350
17
15
81
> 350
(continued on next page)
10

H. Sepehrmansouri et al.
MolecularCatalysisxxx(xxxx)xxx–xxx
Table 2 (continued)
Entry
18
Uracil
Product
Time (min)
15
Yield (%)
83
M.p (˚C)
> 350
19
20
20
20
86
88
> 350
> 350
21
22
20
15
87
93
> 350
> 350
23
15
85
> 350
24
25
15
15
83
84
> 350
> 350
(continued on next page)
11

H. Sepehrmansouri et al.
MolecularCatalysisxxx(xxxx)xxx–xxx
Table 2 (continued)
Entry
26
Uracil
Product
Time (min)
15
Yield (%)
92
M.p (˚C)
> 350
27
28
15
20
87
82
> 350
> 350
29
30
15
15
77a
> 350
> 350
81a
31
20
80a
> 350
32
20
73a
> 350
(continued on next page)
12

H. Sepehrmansouri et al.
MolecularCatalysisxxx(xxxx)xxx–xxx
Table 2 (continued)
Entry
33
Uracil
Product
Time (min)
20
Yield (%)
79a
M.p (˚C)
> 350
a
These products were purified by plate chromatography.
(KBr, cm−1): 3457, 3280, 2962, 2930, 1670, 1619; 1H NMR (400 MHz,
DMSO-d6): δ (ppm):9.31 (s, 1 H), 8.57 (s, 1 H), 8.01 (s, 1 H), 6.82 (d,
J = 1.8 Hz, 1 H), 6.61 (d, J = 8.1 Hz, 1 H), 6.56 (dd, J = 8.2, 1.9 Hz,
1 H), 6.36 (s, 2 H), 4.76 (s, 1 H), 3.95 (qd, J = 6.9, 1.4 Hz, 2 H), 2.49 (d,
J = 17.0 Hz, 1 H), 2.42 (d, J = 17.0 Hz, 1 H), 2.22 (d, J = 16.1 Hz,
1 H), 2.04 (d, J = 16.0 Hz, 1 H), 1.34 (t, J = 7.0 Hz, 3 H), 1.06 (s, 3 H),
0.97 (s, 3 H); 13C NMR (100 MHz, DMSO-d6): δ (ppm): 193.9, 162.3,
153.6, 151.0, 150.9, 145.6, 144.4, 138.7, 119.4, 114.6, 113.5, 109.8,
92.4, 63.7, 50.2, 35.7, 32.4, 32.0, 29.1, 26.5, 14.7. MS m/z (%); found
for C21H24N4O4: 396.4.
Table 3
Evaluation of various catalyst for the synthesis of N-heterocyclic compounds in
comparison with MIL-100(Cr)/NHEtN(CH2PO3H2)2.
Entry Catalyst
(mol%) Time
Yield (%)
(min)
1
2
3
4
5
6
7
SSA
5 mg
60
60
60
60
60
60
60
trace
NaHSO4
5
–
GTBSA [35]
5
45
Al(HSO4)3
5
–
p-TSA
5
–
[Py-SO3H]Cl [36]
[Fe3O4@SiO2@Pr-DABCO-SO3H]Cl2
[37]
5
–
5 mg
trace
2.5.19. 2-Amino-5-(4-isopropylphenyl)-8,8-dimethyl-5,8,9,10-
8
FeCl3
5
60
60
60
60
60
60
60
60
60
60
–
–
–
–
–
–
–
–
–
–
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (19S)
9
H2SO4
5
10
11
12
13
14
15
16
17
Mg(NO3)2.6H2O
Zn(NO3)2.6H2O
NH4NO3
5
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.6; IR
(KBr, cm−1): 3441, 3258, 2960, 2925, 1670, 1625; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.43 (s, 1 H), 9.38 (s, 1 H), 7.16 (d, J = 8.2 Hz,
2 H), 7.10 (d, J = 8.2 Hz, 2 H), 6.40 (s, 2 H), 4.84 (s, 1 H), 2.85 (dt,
J = 13.8, 6.9 Hz, 1 H), 2.53 (d, J = 17.3 Hz, 1 H), 2.47 (d, J = 17.2 Hz,
1 H), 2.24 (d, J = 16.1 Hz, 1 H), 2.07 (d, J = 16.1 Hz, 1 H), 1.22 (s,
3 H), 1.21 (s, 3 H), 1.08 (s, 3 H), 1.00 (s, 3 H); 13C NMR (100 MHz,
DMSO-d6): δ (ppm): 193.9, 153.7, 153.7, 151.3, 151.2, 145.2, 145.0,
127.2, 125.4, 109.7, 109.6, 92.3, 50.1, 32.9, 32.8, 32.0, 28.9, 26.8,
23.9, 23.8. MS m/z (%); found for C22H26N4O2: 378.4.
5
5
Fe3O4
5 mg
H3[p(W3O10)4].XH2O
H3[p(Mo3O10)4].XH2O
Trichloroisocyanuric acid
CF3SO3H
5
5
5
5
2.5.16. 2-Amino-5-(3,5-bis(trifluoromethyl)phenyl)-8,8-dimethyl-
5,8,9,10-tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (16S)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.3; IR
(KBr, cm−1): 3416, 3323, 3173, 3035, 1731, 1671; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.55 (s, 1 H), 9.61 (s, 1 H), 7.90 (s, 1 H), 7.80 (s,
2 H), 6.56 (s, 2 H), 4.99 (s, 1 H), 2.61 (d, J = 3.9 Hz, 1 H), 2.48 (d,
J = 17.5 Hz, 1 H), 2.28 (d, J = 16.1 Hz, 1 H), 2.03 (d, J = 16.2 Hz,
1 H), 1.08 (s, 3 H), 0.94 (s, 3 H); 13C NMR (100 MHz, DMSO-d6): δ
(ppm): δ 194.0, 153.9, 153.8, 152.6, 152.4, 150.5, 129.6, 129.3,
127.81, 122.0, 119.5, 108.2, 90.6, 49.8, 34.5, 32.0, 29.2, 25.8. MS m/z
(%); found for C21H18F6N4O2: 472.3.
2.5.20. 2-Amino-8,8-dimethyl-5-(4-(trifluoromethyl)phenyl)-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (20S)
Brown solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.4; IR
(KBr, cm−1): 3487, 3353, 3272, 2962, 1663, 1624; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.45 (s, 1 H), 9.45 (s, 1 H), 7.54 (d, J = 8.1 Hz,
2 H), 7.38 (d, J = 8.0 Hz, 2 H), 6.41 (s, 2 H), 4.87 (s, 1 H), 2.48-2.35 (m,
2 H), 2.18 (d, J = 16.1 Hz, 1 H), 1.98 (d, J = 16.0 Hz, 1 H), 1.00 (s,
3 H), 0.88 (s, 3 H); 13C NMR (100 MHz, DMSO-d6): δ (ppm): 193.8,
161.3, 154.1, 154.0, 153.9, 152.0, 151.8, 151.7, 128.2, 124.5, 124.4,
108.9, 108.9, 91.32, 91.2, 50.0, 34.0, 32.0, 28.9, 26.6. MS m/z (%);
found for C20H19F3N4O2: 404.3.
2.5.17. 2-Amino-5-(2-hydroxy-3-methoxyphenyl)-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (17S)
Brown solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.8; IR
(KBr, cm−1): 3453, 3354, 3196, 3962, 1648, 1626;1H NMR (400 MHz,
DMSO-d6): δ (ppm):11.01 (s, 1 H), 10.19 (s, 1 H), 9.65 (s, 1 H), 6.70 (dd,
J = 17.5, 7.9 Hz, 3 H), 6.51 (s, 2 H), 5.04 (s, 1 H), 3.75 (s, 3 H), 2.27 (d,
J = 15.9 Hz, 1 H), 2.09 (d, J = 16.2 Hz, 1 H), 1.09 (s, 3 H), 1.07 (s, 3 H);
13C NMR (100 MHz, DMSO-d6): δ (ppm): 194.3, 152.6, 152.5, 149.4,
149.3, 142.9, 142.7, 135.6, 119.4, 119.3, 119.2, 109.9, 109.1, 91.8,
55.3, 49.9, 32.0, 28.9, 27.0, 26.9. MS m/z (%); found for C20H22N4O4:
382.4.
2.5.21. 5-(4-Bromophenyl)-8,8-dimethyl-2,4-dithioxo-2,3,4,5,7,8,9,10-
octahydropyrimido[4,5-b]quinolin-6(1 H)-one (1 M)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.6; IR
(KBr, cm−1): 3248, 3166, 2930, 2867, 1638; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.27 (s, 1 H), 9.53 (S, 1 H), 8.03 (S, 1 H), 7.41 (d,
2 H), 7.06 (d, 2 H), 4.85 (s, 1 H), 2.52- 2.36 (m, 2 H), 2.23 (d, 1 H), 2.04
(d, J = 10.2 Hz, 1 H), 1.07 (S, 3 H), 0.95 (S, 3 H) ; 13C NMR (100 MHz,
DMSO-d6): δ (ppm): 193.5, 162.3, 152.0, 147.3, 130.2, 129.7, 118.1,
108.6, 50.1, 35.7, 32.0, 30.7, 28.9, 26.7. MS m/z (%); found for
2.5.18. 2-Amino-5-(3-ethoxy-4-hydroxyphenyl)-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione (18S)
C19H18BrN3OS4: 448.4.
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.5; IR
13

H. Sepehrmansouri et al.
MolecularCatalysisxxx(xxxx)xxx–xxx
Scheme 4. Plausible mechanism for the synthesis N-heterocyclic compounds using MIL-100(Cr)/NHEtN(CH2PO3H2)2.
Fig. 7. Recyclability of MIL-100(Cr)/NHETN(CH2PO3H2)2 as catalyst in the
synthesis of tetrahydropyrimido[4,5-b]quinolone.
Fig. 8. FT-IR of MIL-100(Cr)/NHETN(CH2PO3H2)2 in a) reused (red) b) fresh
(blue) (For interpretation of the references to colour in this figure legend, the
reader is referred to the web version of this article).
2.5.22. 5-(4-Chlorophenyl)-8,8-dimethyl-2,4-dithioxo-2,3,4,5,7,8,9,10-
octahydropyrimido[4,5-b]quinolin-6(1 H)-one (2 M)
2.5.23. 5-(4-Methoxyphenyl)-8,8-dimethyl-2,4-dithioxo-2,3,4,5,7,8,9,10-
octahydropyrimido[4,5-b]quinolin-6(1 H)-one (3 M)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.75; IR
(KBr, cm−1): 3433, 3329, 3090,2928, 1660, 1649; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 12.23 (s, 1 H), 11.79 (s, 1 H), 8.67 (s, 1 H), 7.31 (d,
J = 8.5 Hz, 2 H), 7.25 (d, J = 8.5 Hz, 2 H), 4.78 (s, 1 H), 2.53- 2.41 (m,
J = 13.9 Hz, 2 H), 2.25 (d, J = 16.1 Hz, 1 H), 2.08 (d, J = 16.1 Hz,
1 H), 1.07 (s, 3 H), 0.93 (s, 3 H); 13C NMR (100 MHz, DMSO-d6): δ
(ppm): 194.2, 173.4, 160.1, 148.9, 144.7, 143.7, 130.5, 129.4, 127.7,
110.5, 93.6, 50.0, 32.8, 32.1, 28.7, 26.4. MS m/z (%); found for
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.7; IR
(KBr, cm−1): 3458, 3275, 2958, 1642, 1612; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 12.12 (s, 1 H), 8.66 (s, 1 H), 8.03 (s, 1 H), 7.16 (d,
2 H), 6.83 (d, 2 H), 4.76 (s, 1 H), 3.76 (s, 3 H), 2.56- 2.45 (m, 2 H), 2.28
(d, J = 16.1, 3.0 Hz, 1 H), 2.09 (d, 1 H), 1.10 (s, 3 H), 0.98 (s, 3 H) ;13
C
NMR (100 MHz, DMSO-d6): δ (ppm): 194.2, 173.3, 162.2, 160.1, 157.4,
148.5, 143.6, 142.8, 138.1, 128.5, 113.1, 111.1, 94.3, 54.8, 50.0, 35.7,
32.1, 30.7, 28.8, 26.4. MS m/z (%); found for C20H21N3O2S2: 399.3.
C
19H18ClN3OS4: 403.9.
14

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2.5.24. 5-(2-Hydroxy-3-methoxyphenyl)-8,8-dimethyl-2,4-dithioxo-
2,3,4,5,7,8,9,10-octahydropyrimido[4,5-b]quinolin-6(1 H)-one (4 M)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.8; IR
(KBr, cm−1): 3660, 3314, 2896, 1640, 1622; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 11.62 (s, 1 H), 11.50 (s, 1 H), 7.02 (t, J = 7.9 Hz,
1 H), 6.92 (d, J = 7.4 Hz, 1 H), 6.70 (s, 1 H), 6.67 (d, J = 7.2 Hz, 1 H),
4.78 (s, 1 H), 3.88 (s, 3 H), 2.63 (d, 1 H), 2.48 (d, 1 H), 2.32 (d, 1 H),
2.18 (d, J = 13.0, 7.7 Hz, 1 H), 1.13 (s, 3 H), 1.06 (s, 3 H) ; 13C NMR
(100 MHz, DMSO-d6): δ (ppm): 196.2, 172.8, 165.3, 159.8, 150.3,
146.5, 139.4, 124.8, 123.7, 119.8, 109.8, 109.1, 94.6, 55.4, 50.3, 40.5,
31.7, 28.8, 26.4. MS m/z (%); found for C20H21N3O3S2: 415.5.
1 H), 2.41 (d, J = 24.2 Hz, 2 H), 2.13 (dd, J = 32.3, 16.3 Hz, 2 H), 1.01
(s, 3 H), 0.90 (s, 3 H).13C NMR (100 MHz, DMSO-d6): δ (ppm): 194.3,
173.2, 162.2, 160.1, 148.8, 143.2, 126.8, 110.9, 93.8, 50.0, 35.7, 32.2,
32.0, 30.7, 28.4, 26.9. MS m/z (%); found for C32H32N6O2S4: 660.8.
2.5.30. 5,5′-(1,4-Phenylene)bis(2-amino-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione)(2A)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.65; IR
(KBr, cm−1): 3451, 3326, 2956, 2934, 1620; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.36 (s, 2 H), 9.33 (s, 2 H), 7.01 (d, J = 2.7 Hz,
4 H), 6.36 (s, 4 H), 4.80 (d, J = 4.2 Hz, 2 H), 2.45 (d, J = 16.0 Hz, 4 H),
2.21- 2.05 (m, 4 H), 1.07 (d, J = 11.2 Hz, 6 H), 0.99 (s, 3 H), 0.95 (s,
3 H); 13C NMR (100 MHz, DMSO-d6): δ (ppm): 193.8, 161.3, 153.8,
151.4, 151.2, 144.6, 144.5, 126.5, 109.8, 109.6, 92.1, 50.1, 32.5, 32.1,
28.7, 28.5, 27.4, 27.0. MS m/z (%); found for C32H34N8O4: 594.6.
2.5.25. 5-(3-Ethoxy-4-hydroxyphenyl)-8,8-dimethyl-2,4-dithioxo-
2,3,4,5,7,8,9,10-octahydropyrimido[4,5-b]quinolin-6(1 H)-one (5 M)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.65; IR
(KBr, cm−1): 3391, 3173, 2856, 1638; 1H NMR (400 MHz, DMSO-d6): δ
(ppm): 12.04 (s, 1 H), 9.36 (s, 1 H), 8.67 (s, 1 H), 8.52 (s, 1 H), 8.01 (s,
1 H), 6.84 (s, 1 H), 6.70- 6.39 (m, 2 H), 4.76 (s, 1 H), 3.95 (q,
J = 6.9 Hz, 2 H), 2.56 – 2.31 (m, 2 H), 2.21 (d, J = 16.1 Hz, 1 H), 2.03
(d, J = 16.1 Hz, 1 H), 1.34 (t, J = 12.6, 6.2 Hz, 3 H), 1.01 (d,
J = 33.9 Hz, 6 H). 13C NMR (100 MHz, DMSO-d6): δ (ppm): 193.7,
146.2, 145.6, 144.2, 119.3, 118.7, 115.0, 114.7, 113.5, 112.6, 109.30,
76.4, 63.9, 63.7, 50.3, 35.7, 32.0, 29.1, 26.6, 14.8, 14.7. MS m/z (%);
found for C21H23N3O3S2: 429.5.
2.5.31. 5,5′-(1,4-Phenylene)bis(8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-2,4,6(1H,3H,7 H)-trione) (3 A)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.7, IR
(KBr, cm−1): 3191, 2959, 1731, 1659; 13C NMR (100 MHz, DMSO-d6): δ
(ppm): 192.0, 165.7, 162.4, 149.8, 135.7, 125.8, 84.8, 74.4, 47.7, 42.1,
31.9, 22.8, 22.4. MS m/z (%); found for C32H32N6O4: 596.6.
2.5.32. 5,5′-(1,3-Phenylene)bis(2-amino-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione) (4 A)
2.5.26. 8,8-Dimethyl-5-(4-nitrophenyl)-2,4-dithioxo-2,3,4,5,7,8,9,10-
octahydropyrimido[4,5-b]quinolin-6(1 H)-one(6 M)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.65; IR
(KBr, cm−1): 3422, 3337, 3187, 2955, 1655; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.23 (d, J = 11.5 Hz, 2 H), 9.21 (s, 1 H), 9.16 (s,
1 H), 7.07 (s, 1 H), 6.98 – 6.93 (m, 1 H), 6.93- 6.82 (m, 3 H), 6.25 (s,
2 H), 6.20 (s, 2 H), 4.77 (s, 1 H), 4.67 (s, 1 H), 2.38 (dd, J = 28.4,
18.0 Hz, 4 H), 2.15- 2.00 (m, 3 H), 1.86 (d, J = 15.9 Hz, 1 H), 1.03- 0.93
(m, 9 H), 0.82 (s, 3 H).13C NMR (100 MHz, DMSO-d6): δ (ppm): 193.8,
193.6, 161.3, 153.9, 153.6, 153.6, 151.4, 151.1, 147.3, 146.7, 125.5,
124.4, 109.6, 109.4, 92.4, 92.0, 50.3, 50.2, 33.3, 32.5, 32.0, 31.8, 29.2,
28.5, 27.7, 26.6. MS m/z (%); found for C32H34N8O4: 594.60.
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.5; IR
(KBr, cm−1): 3331, 2974, 2934, 1639, 1601; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.26 (s, 1 H), 9.65 (s, 1 H), 8.14 (d, J = 8.7 Hz,
2 H), 8.05 (s, 1 H), 7.51 (d, J = 8.7 Hz, 2 H), 4.97 (s, 1 H), 2.53 (d,
J = 17.1 Hz, 1 H), 2.44 (d, J = 16.3 Hz, 1 H), 2.25 (d, J = 16.0 Hz,
1 H), 2.05 (d, J = 16.0 Hz, 1 H), 1.09 (s, 3 H), 0.97 (s, 3 H); 13C NMR
(100 MHz, DMSO-d6): δ (ppm): 193.2, 162.3, 155.6, 152.8, 145.3,
128.4, 123.3, 107.8, 50.0, 35.7, 34.3, 32.2, 29.0, 26.5, 18.4. MS m/z
(%); found for C19H18N4O3S2: 414.5.
2.5.33. 5,5′-(1,3-phenylene)bis(8,8-dimethyl-2,4-dithioxo-
2.5.27. 8,8-Dimethyl-5-phenyl-5,8,9,10-tetrahydropyrimido[4,5-b]
quinoline-2,4,6(1H,3H,7 H)-trione (1B)
2,3,4,5,7,8,9,10-octahydropyrimido[4,5-b]quinolin-6(1 H)-one) (5 A)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.8; IR
(KBr, cm−1): 3331, 3176, 2955, 1670, 1640; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.52 (s, 1 H), 9.51 (s, 1 H), 6.98 (s, 1 H), 6.91 (s,
1 H), 4.60 (s, 1 H), 2.44 (d, J = 23.9 Hz, 1 H), 2.30 (d, J = 17.0 Hz,
1 H), 2.16 (d, J = 16.1 Hz, 1 H), 1.88 (d, J = 16.0 Hz, 1 H), 0.97 (s,
3 H), 0.77 (s, 3 H). 13C NMR (100 MHz, DMSO-d6): δ (ppm): 194.0,
162.7, 162.7, 146.9, 125.8, 125.5, 125.4, 111.0, 90.1, 49.9, 32.8, 32.0,
31.7, 29.2, 28.6, 27.0, 25.8.MS m/z (%); found for C32H32N6O2S4:
660.8.
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.5; IR
(KBr, cm−1): 3322, 3163, 2971,1717, 1640; 1H NMR (400 MHz, DMSO-
d6): δ (ppm): 10.81-10.53 (m, 1 H), 10.51-10.24 (m, 1 H), 7.28- 7.18
(m, 4 H), 7.10 (s, 1 H), 6.73 (s, 1 H), 4.71 (s, 1 H), 2.48 – 2.38 (m, 2 H),
2.21 (d, J = 16.4 Hz, 1 H), 2.02 (d, J = 14.8 Hz, 1 H), 1.02 (s, 3 H), 0.88
(s, 3 H). 13C NMR (100 MHz, DMSO-d6): δ (ppm): 194.2, 162.7, 149.7,
145.5, 138.6, 130.2, 129.4, 128.5, 127.6, 127.4, 110.6, 89.1, 59.7,
50.02, 32.8, 32.1, 28.8, 26.4, 20.7, 14.0. MS m/z (%); found for
C
19H19N3O3: 337.3.
3. Results and discussion
2.5.28. 5-(4-(Dimethylamino)phenyl)-8,8-dimethyl-5,8,9,10-
tetrahydropyrimido[4,5-b]quinoline-2,4,6(1H,3H,7 H)-trione (2B)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.6; IR
(KBr, cm−1): 3416, 3323, 3055, 1731, 1642; 1H NMR (400 MHz,
DMSO-d6): δ (ppm): 10.73 (s, 1 H), 10.14 (d, J = 9.7 Hz, 1 H), 7.04 (d,
J = 8.7 Hz, 2 H), 6.61 (d, J = 8.7 Hz, 2 H), 6.24 (s, 1 H), 4.68 (s, 1 H),
4.47 (s, 1 H), 2.86 (s, 6 H), 2.53- 2.40 (m, 2 H), 2.25 (d, J = 16.1 Hz,
1 H), 2.06 (d, J = 16.1 Hz, 1 H), 1.08 (s, 3 H), 0.96 (s, 3 H); 13C NMR
(100 MHz, DMSO-d6): δ (ppm): 194.3, 164.2, 162.7, 155.0, 150.9,
148.7, 148.6, 134.8, 127.9, 112.0, 111.6, 90.1, 74.0, 50.1, 40.3, 32.1,
31.7, 29.0, 26.4. MS m/z (%); found for C21H24N4O3: 380.4.
Initially, MIL-100(Cr)/NHEtN(CH2PO3H2)2 was prepared as MOFs
catalyst by the condensation reaction of MIL-100(Cr)/NHEtNH2, par-
aformaldehyde, phosphorous acid, HCl and EtOH as solvent under re-
flux condition (path method [32,33]) (Scheme 2). The structure of
MOFs linker phosphorous acid was confirmed by several techniques
such as, fourier transform infrared spectroscopy (FT-IR), EDX, ele-
mental mapping, scanning electron microscopy (SEM), transmission
electron microscopy (TEM), N2 adsorption-desorption isotherms (BET),
thermal gravimetric (TG), differential thermal gravimetric (DTG) and
differential thermal analysis (DTA).
The comparison FT-IR spectrum of catalyst and MIL-100(Cr)/
NHEtNH2 were showed in Fig. 1. As it is shown in Fig. 1, a broad peak
was displayed at about 2679–3402 cm−1 related to OH of PO3H2 groups
in the structure of the catalyst. The peaks between 2800–2940 cm−1
can be attributed to the presence of C–H of alkyl chain of propyl group
and C–H of other methylenes besides of PO3H2 groups. The peak related
2.5.29. 5,5′-(1,4-Phenylene)bis(8,8-dimethyl-2,4-dithioxo-
2,3,4,5,7,8,9,10-octahydropyrimido[4,5-b]quinolin-6(1 H)-one) (1 A)
White solid; Mp: > 350 °C; Rf: (n-hexane: acetone 1:1) = 0.7; IR
(KBr, cm−1): 3473, 3232, 2938, 1683; 1H NMR (400 MHz, DMSO-d6): δ
(ppm): 12.12 (s, 1 H), 11.65 (s, 1 H), 8.48 (s, 1 H), 7.96 (s, 2 H), 7.01 (s,
15

H. Sepehrmansouri et al.
MolecularCatalysisxxx(xxxx)xxx–xxx
to PeO bond was observed at about 1080 cm−1. Furthermore, two
peaks related to Cr-O of octahedral CrO6 were appeared at 523 and
663 cm−1 respectively. Two peaks at about 1393 and 1642 cm−1 were
corresponded to asymmetric and symmetric vibrations of C]C [34].
SEM-EDS analysis of the catalyst was studied in comparison with
MIL-100(Cr)/NHEtNH2. The structure of MIL-100(Cr)/NHEtN
(CH2PO3H2)2 was verified the existence of Cr, C, O, N and P atoms
whereas the structure of MIL-100(Cr)/NHEtNH2 which is contained Cr,
C, O and N atoms. Then, SEM-elemental mapping (Cr, C, N, O and P) in
the MOFs-catalyst with a well-dispersed over the catalyst surface was
confirmed (Fig. 2). Elemental analysis of the catalyst was verified C:
43.09, N: 12.85 and P: 11.16.
preparation of 2-amino-5-(4-chlorophenyl)-8,8-dimethyl-5,8,9,10-tet-
rahydropyrimido[4,5-b]quinoline-4,6(3H,7H)-dione by the reaction of
4-chloro benzaldehyde (1 mmol, 0.14 g), 2,6-diaminopyrimidin-4(3H)-
one (1 mmol, 0.126 g) and dimedone (1 mmol, 0.14 g), we have used
different organic and inorganic acid catalysts for the condensation re-
action between 4-chloro benzaldehyde (1 mmol, 0.14 g), 2,6-diamino-
pyrimidin-4(3H)-one (1 mmol, 0.126 g) and dimedone (1 mmol,
0.14 g), in Table 3. As Table
3 indicates, MIL-100(Cr)/NHEtN
(CH2PO3H2)2 is the best catalyst for the synthesis of N-heterocyclic
compounds.
A proposed mechanism for the synthesis of N-heterocyclic com-
pounds was displayed in Scheme 4. Firstly, dimedone, in enol form, was
reacted with aldehyde which is activated by MIL-100(Cr)/NHETN
(CH2PO3H2)2 to give I as a Michael acceptor after removing of one
molecule of H2O. Then, uracil derivative compound was reacted with I
to prepare II which converted to III after cyclization reaction. Finally,
by removing of one molecule of H2O, the desired product was obtained.
According to the results in Fig. 7, MIL-100(Cr)/NHETN(CH2PO3H2)2
can be separated by centrifugation and reused without significantly
reducing of catalytic activity, for this purpose recyclability of the cat-
alyst was tested on the reaction of 2,6-diamino pyrimidin-4(3H)-one
(1 mmol, 0.126 g) with 4-chloro benzaldehyde (1 mmol, 0.14 g) and
dimedone (1 mmol, 0.14 g) as a model reaction. Therefore, MIL-
100(Cr)/NHETN(CH2PO3H2)2 can be reused up to eight runs without
noticeable changes in the catalytic activity. The reused catalyst was also
characterized by FT-IR after its catalytic application in the reaction. The
FT-IR spectra of the fresh catalyst and reused catalyst were compared
with each other in Fig. 8.
To distinguish the surface morphology of the synthesized MIL-
100(Cr)/NHEtN(CH2PO3H2)2 SEM was studied. SEM micrographs of the
MOFs-catalyst showed that the particles have not completely agglom-
erated. Moreover, particles of the MOFs-catalyst were observed in
average size of 35 nm (Fig. 3).
In another investigation, we have studied transmission electron
microscopy (TEM) to verify the structure of MOFs-catalyst in Fig. 4. The
TEM images of MIL-100(Cr)/NHEtN(CH2PO3H2)2 showed that the
particles prepared in nano size with proper dispersion.
In the direction study of thermal stability of the MOFs-catalyst, the
thermal gravimetric (TG), derivative thermal gravimetric (DTG), as
well as the differential thermal analysis (DTA) were investigated
(Fig. 5). The first weight loss, was happened between 25 and 100 °C,
associated with the removal of possible solvents (organic and water).
The main stage of weight loss, disrupts the structure of MIL-100(Cr)/
NHEtN(CH2PO3H2)2, was happened after 200 °C, and includes about
40% weight loss. Therefore, this catalyst can be used up to 200 °C.
Nitrogen adsorption-desorption isotherm (BET) of En/MIL-100(Cr)
and MIL-100(Cr)/NHEtN(CH2PO3H2)2 were compared in Fig. 6. These
isotherms reveal that the hysteresis loop progressively shifts to lower
relative pressures with grafting of PO3H2 group (−CH2PO3H2) in-
dicative of decreasing pore size and surface area decreased from 460 to
100 m2/g. BET surface area, and total pore volume of En/MIL-100(Cr)
are 223.5 m2 g−1 and 0.19 cm3 g−1 and for MIL-100(Cr)/NHEtN
(CH2PO3H2)2 are 84.0 m2 g−1 and 0.24 cm3 g−1 respectively.
4. Conclusion
In this work, we have reported a new multifunctional of the MIL-
100(Cr)/En metal-organic framework with phosphorous acid namely
MIL-100(Cr)/NHEtN(CH2PO3H2)2 as an efficient nanoporous catalyst.
MIL-100(Cr)/NHEtN(CH2PO3H2)2 was fully characterized by FT-IR,
SEM-Elemental Mapping., EDX, TEM, TGA and BET and successfully
used for the synthesis of some new biological N-heterocyclic com-
pounds containing uracil moiety such as tetrahydropyrimido[4,5-b]
In addition, the catalytic activity of MIL-100(Cr)/NHEtN
(CH2PO3H2)2 was tested in one-pot synthesis of 2-amino-5-(4-chlor-
ophenyl)-8,8-dimethyl-5,8,9,10-tetrahydropyrimido[4,5-b]quinoline-
4,6(3H,7H)-dione by the reaction of 4-chloro benzaldehyde (1 mmol,
0.14 g), 2,6-diaminopyrimidin-4(3H)-one (1 mmol, 0.126 g) and dime-
done (1 mmol, 0.14 g) as a model reaction and optimized (Table 1). In
the first experiment, model reaction was tested using DMF as a solvent,
0.01 (g) MOFs-catalyst at 25–100 °C which was obtained greatest yield
at 100 °C (Table 1, entry 4). By testing different amounts MOFs-catalyst,
the highest yield was obtained in the presence of 0.01 (g) MOFs-catalyst
(Table 1, entry 5–7). Different solvents including DMF, H2O, EtOH,
CH2Cl2, CHCl3, EtOAc, CH3CN in comparison with solvent-free condi-
tion were tested on the model reaction which the best result was ob-
served in the presence of DMF as a solvent (Table 1, entry 8–14).
After the optimization of the reaction conditions, the efficiency and
applicability of MIL-100(Cr)/NHEtN(CH2PO3H2)2 were studied by the
reaction of dimedone and uracil derivatives compound such as 6-ami-
quinoline-2,4,6(1H,3H,7H)-trione,
tetrahydropyrimido[4,5-b]quino-
line-4,6(3H,7H)-dione and octahydropyrimido[4,5-b]quinolin-6(1H)-
one derivatives. Major advantages of this work are high yield of pro-
ducts, short reaction times, facile workup and reusability of the cata-
lyst.
Acknowledgements
We thank Bu-Ali Sina University, Sayyed Jamaleddin Asadabadi
University, National Elites Foundation and Iran National Science
Foundation (INSF) (grant number:96003376) for financial support to
our research group.
Appendix A. Supplementary data
Supplementary material related to this article can be found, in the
online version, at doi:https://doi.org/10.1016/j.mcat.2019.01.023.
nopyrimidine-2,4(1H,3H)-dione,
6-aminopyrimidine-2,4(1H,3H)-di-
thione and 2,6-diaminopyrimidin-4(3H)-one with various aldehydes.
The results are depicted in Table 2. As Table 2 indicates that, all al-
dehydes including benzaldehyde as well as other aromatic aldehydes
possessing electron-releasing substituents, electron withdrawing sub-
stituents, basic groups or halogens afforded the desired N-heterocyclic
compounds such as tetrahydropyrimido[4,5-b]quinoline-2,4,6(1H,
3H,7H)-trione, tetrahydropyrimido[4,5-b]quinoline-4,6(3H,7 H)-dione
and octahydropyrimido[4,5-b]quinolin-6(1H)-one derivatives with
short reaction times in high to excellent yields (73–93%) (5–30 min)
(Table 2).
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