Synthesis of functionalized pyrimidouracils by ruthenium-catalyzed oxidative insertion of (hetero)aryl methanols into N-uracil amidines

Article abstract of DOI:10.1002/aoc.6087

A dehydrogenative coupling of N-uracil amidines with (hetero)aryl methanols has been developed, allowing for the facile synthesis of a broad range of structurally diverse pyrimidouracils. By applying [RuCl₂(p-cymene)]₂/Cs₂CO₃ as an efficient catalytic system, the easily available, cheap (hetero)aryl methanols were firstly employed for oxidative insertion/C-H amination into the N-uracil amidines, providing highly functionalized pyrimido[4,5-d]pyrimidine-2,4-diones. Due to the better stability of alcohols than aldehydes, this synthetic protocol is applicable to a broad range of alcoholic substrates and does not required any protection during the whole preparation process. The presented protocol has the potential to prepare valuable products which cannot be accessed presently or extremely arduous to procure by following regular procedure. Hence, this is a remarkably improved protocol compared with the existing methodologies. The overall reaction sequence is an effective oxidation-imination-cyclization tandem process catalyzed by ruthenium catalyst.

Full text of DOI:10.1002/aoc.6087

Received: 20 August 2020
DOI: 10.1002/aoc.6087
Revised: 15 October 2020
Accepted: 16 October 2020
F U L L P A P E R
Synthesis of functionalized pyrimidouracils by ruthenium-
catalyzed oxidative insertion of (hetero)aryl methanols into
N-uracil amidines
Pradip Debnath1
| Gouranga Sahu2
| Utpal C. De3
1Department of Chemistry, Maharaja Bir
Bikram College, Agartala, India
2Department of Chemistry, Ramkrishna
Mahavidyalaya, Unakoti, India
3Department of Chemistry, Tripura
University, Agartala, India
A dehydrogenative coupling of N-uracil amidines with (hetero)aryl methanols
has been developed, allowing for the facile synthesis of a broad range of struc-
turally diverse pyrimidouracils. By applying [RuCl2(p-cymene)]2/Cs2CO3 as an
efficient catalytic system, the easily available, cheap (hetero)aryl methanols
were firstly employed for oxidative insertion/C H amination into the N-uracil
amidines, providing highly functionalized pyrimido[4,5-d]pyrimidine-
2,4-diones. Due to the better stability of alcohols than aldehydes, this synthetic
protocol is applicable to a broad range of alcoholic substrates and does not
required any protection during the whole preparation process. The presented
protocol has the potential to prepare valuable products which cannot be
accessed presently or extremely arduous to procure by following regular proce-
dure. Hence, this is a remarkably improved protocol compared with the
existing methodologies. The overall reaction sequence is an effective oxidation-
imination-cyclization tandem process catalyzed by ruthenium catalyst.
Correspondence
Dr. Pradip Debnath, Department of
Chemistry, Maharaja Bir Bikram College,
Agartala, Tripura 799004, India.
Email: pradipchem78@gmail.com
Funding information
Department of Science and Technology
(DST), New Delhi, Grant/Award Number:
YSS/2015/001554
K E Y W O R D S
(hetero)aryl methanols, N-uracil amidine, oxidation, pyrimidopyrimidine, ruthenium catalyst,
tandem process
1 | INTRODUCTION
creates less waste. Transition metal catalyzed such as
C N bond forming reactions is therefore a methodology
Nitrogen-containing heterocycles are very important
structural motifs found in numerous natural products
and potent pharmaceutical drugs.[1] These molecules also
enjoy widespread application in the field of organic syn-
thesis, agrochemicals, pesticides, and pharmaceuticals
industries.[2] For these reasons, several efforts have been
paid to develop novel and efficient methods for the syn-
thesis of this class of molecules.[3] Over the past decade,
the transition metal–catalyzed C H bond activation/
C H amination has achieved remarkable progress for
the construction of nitrogen heterocycles because of its
economic, sustainable, and environmentally benign fea-
tures.[4] Leaving out the necessity for preactivation
shortens the total number of required synthetic steps and
contributing to the important field of sustainable
chemistry.
Pyrimidines are one of the most important nitrogen
heterocycles, exhibiting remarkable pharmaceutical activi-
ties.[5] Fused pyrimidines scaffolds such as pyrimidouracils
and pyrimidopyrimidines are the important classes of
annulated pyrimidines found in various drug candidates
and natural products showing a broad spectrum of biologi-
cal activities,[6] such as adenosine potentiating (coronary
dilators),[7] anticancer,[8] antiviral,[9] antifungal,[10]
antioxidant,[11] antitumor,[12] and hepatoprotective.[13]
Compounds with these ring systems are also useful as
bronchodilators,[8] vasodilators,[14] antiallergic,[15] and
antihypertensive[16] agents. Moreover, similar molecules
Appl Organomet Chem. 2020;e6087.
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https://doi.org/10.1002/aoc.6087

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DEBNATH ET AL.
have also been act as phosphoribosyl-1-pyrophosphate
synthetase inhibitors[17] and dihydrofolate reductase
inhibitors.[18] For example, pyrimidopyrimidine-based
compound such as dipyridamole is a medicine that per-
forms several functions like phosphodiesterase enzyme
inhibition and lowering of pulmonary hypertension.[19]
This medicine has also been found to be used in echocar-
diography and electrocardiogram. Folic acid conjugated
pyrimido[4,5-d]pyrimidine analogues is currently under-
going clinical trials as an antitumor agent.[20] Although
these pyrimido[4,5-d]pyrimidines show a broad range of
biologically activities, the current synthesis[21–23] of these
scaffolds have very limited scope, utilize highly specific
reactions, or require harsh reaction conditions. The most
frequently used methods to construct pyrimido[4,5-d]
pyrimidine-2,4-diones (pyrimidouracils) mainly rely
on the multicomponent reactions (MCRs) using
6-aminouracils[21] or the cycloaddition reactions involving
6-methylideneaminouracils and electron-deficient sub-
strates.[22] The cycloaddition reactions are limited to elec-
tron deficient substrates only, and hence, those not offer
liberal scope for the preparation of products. Interestingly,
functionalized pyrimidouracils can be synthesized via the
direct condensation of aromatic aldehydes and N-uracil
amidines.[24] However, the use of aldehydes as the cou-
pling partners poses several shortcomings like (a) some
active aldehyde groups may undergo an oxidation reaction
which can potentially form unwanted by-products, and
therefore, for resisting this, inert conditions are
required[25]; (b) some reactive aldehydes may undergo a
decarbonylation reaction under tough reaction condi-
tions[26]; (c) moreover, high cost or nonavailability of some
aldehydes such as heteroaryl ones restricted the synthesis
of variable products. In order to alleviate these shortcom-
ings, it is necessary to develop more viable and sustainable
chemical procedures for the synthesis of this class of
molecules. Recently, a synthetic protocol have been
developed by Deb and coworkers for the preparation of
5,6-dihydropyrimidouracils involving three-component
reaction between 6-aminouracil, aldehyde and tetra-
hydroisoquinolines under solid state reaction condi-
tions.[27] We have also shown that pyrimidouracils could
be achieved by the direct annulation of N-uracil amidines
with methylarenes under oxidative reaction conditions.[28]
Very recently, Bert and coworkers reported the synthesis
of 4-amino-substituted pyrimidouracils by nickel(II)-
catalyzed isocyanide insertion into N-uracil amidines.[29]
Therefore, it is imperative to search for readily available,
cheap, and stable substitutes of aldehydes which would
usher in fresh avenue for the synthesis of pyrimidouracils.
Of late, in carbon–carbon (C C) and carbon-nitrogen
(C N) bond formations, the utilization of sustainable
alcohols has gained prominence.[30] Alcohols are known
to be stable and less toxic. Beside these, they are cheap,
readily accessible, and easier to handle than aldehydes.
Therefore, it is comfortable to use alcohols as starting
material in different chemical transformations. By apply-
ing suitable oxidizing reagents, the dehydrogenative oxi-
dation of alcohols leads to in situ formation of aldehydes.
Thus, the oxidation of alcohols is to be considered as a
key step in the formation of products.[31,32] On the basis
of these findings, it can be assumed that alcohols could
be applied as latent aldehydes for the preparation of aryl
substituted pyrimidouracils starting from N-uracil
amidines (Scheme 1). The use of alcohols has several
advantages such as they are inexpensive as compared
with aldehydes, thermodynamically more stable, abun-
dance, and sustainable. Therefore, by replacing aldehydes
with alcohols would allow us to synthesize functionalized
pyrimidouracils of biological interest.
Herein, the endeavor is to develop a new protocol for
the synthesis of N1, N3, C5, and C7 tetrasubstituted
pyrimidouracils directly from N-uracil amidine and
(hetero)aryl methanols under ruthenium-catalyzed
dehydrogenative oxidation conditions. The starting mate-
rials, the N-uracil-amidines 1, can readily be obtained
from 6-chlorouracil by the nucleophilic substitution reac-
tions with amidines.[24,33] The overall reaction process is
the oxidation-imination-cyclization tandem process cata-
lyzed by ruthenium catalyst. The requisite amidine sub-
strates can be easily prepared from the corresponding
nitriles and ammonia by applying Pinner approach.[34]
The substituent (R) at C7 position of the products was
installed from these amidines. To the best of our knowl-
edge, such synthetic protocol using inexpensive (hetero)
aryl methanols was firstly employed for the synthesis of
substituted
pyrimido[4,5-d]pyrimidine-2,4-diones
(pyrimidouracils).
2 | RESULTS AND DISCUSSION
With the above described idea in mind, the possibility of
direct synthesis of tetrasubstituted pyrimidouracils (3a)
from N-uracil amidine (1a) and benzyl alcohol (2a)
(Table 1) were examined. The reaction was initially con-
ducted at 110ꢀC for 15 h using 1.5 equivalent of K2CO3 in
dimethylsulfoxide (DMSO). However, even trace
amounts of the desired product were not obtained
(Table 1, entry 1). The desired product of pyrimido[4,5-d]
pyrimidine-2,4-dione (3a) was obtained in 19% yield
when 2 mol% of RuCl3 was introduced into the reaction
mixture under the same conditions (Table 1, entry 2).
Encouraged by this result, the screening of ruthenium
catalysts (Figure 1) using the same reaction conditions
was performed (Table 1, entries 2–7). [RuCl2(p-

DEBNATH ET AL.
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SCHEME 1 Direct oxidative and oxidative
imidoylative amination of N-uracil-amidines
TABLE 1 Optimization of
conditions for the oxidative insertion of
benzyl alcohol (2a) into N-uracil
benzamidine (1a), towards the synthesis
of pyrimidouracil (3a)
Entry
Catalyst (2 mol%)
-
Base (1.5 eq.)
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K3PO4
Solvent (1 ml)
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMF
Yield (%)a
1
-
19
27
20
32
43
52
37
31
70
14
>10
61
30
37
41
69
66
85
84
2
Cat 1
Cat 2
Cat 3
Cat 4
Cat 5
Cat 6
Cat 6
Cat 6
Cat 6
Cat 6
Cat 6
Cat 6
Cat 6
Cat 6
Cat 6
Cat 6
Cat 6
Cat 6
Cat 6
3
4
5
6
7
8
9
KOAc
10
11
12
13
14
15
16
17b
18c
19d
20e
Cs2CO3
DBU
Et3N
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Toluene
THF
tBuOH
DMSO
DMSO
DMSO
DMSO
Note: Reaction conditions: unless otherwise specified, all reactions were performed out without inert gas
protection by using 1a (0.5 mmol, 1 eq.), 2a (0.75 mmol, 1.5 eq), catalyst (2 mol%), base (0.75 mmol, 1.5 eq),
solvent (1 ml), 110ꢀC, 15 h.
Abbreviations: DMF, dimethylformamide; DMSO, dimethylsulfoxide; THF, tetrahydrofuran.
aIsolated yield of 3a.
bReaction time 20 h (entry 17).
cReaction carried out at 120ꢀC (entry 18).
dReaction performed with 2.5 mol% catalyst (entry 19).
eReaction performed with 3 mol% of catalyst (entry 20).

4 of 9
DEBNATH ET AL.
multiple substituents and furnished desired products in
good to excellent yields. Under the optimal reaction con-
ditions, aryl methanols bearing electron-donating substit-
uents such as Me,
OMe,
SMe,
OH including
halogen ( Cl) produced respective pyrimidouracils 3b–
3g and 3p–3r in very good yields (68%–96%) whereas aryl
methanols bearing strong electron-withdrawing groups
such as F and CN produced to some extent lower yield of
the products 3l and 3m. It has been observed that aryl
methanols having para- and meta-substituents yielded
higher products than those with ortho-substituents (2b,
2i, 2r). This may be due to the steric hindrances in ortho-
substituted alcohols. Moreover, when the same N-uracil
amidine (1a) is used, the substituents on the aryl ring of
aryl methanols possessing different electron properties
slightly influence the product yields. In general, electron-
rich substrate such as aryl methanols containing methoxy
group ( OMe) yielded relatively higher products (3e,
3q), which could be attributed to its better inherent
stability compared with other aryl methanols. Apart
from this, 1-naphthalenemethanol as well as
2-naphthalenemethanol have been found to smoothly
react with N-uracil amidine under the optimal reaction
conditions providing 3n and 3o in 92% and 89% yields,
respectively. The oxidation-sensitive functional groups
such as a thiomethyl group (2f) were found to be compat-
ible with the reaction conditions. The reaction also
proceeded smoothly with the use of multiple substituted
aryl methanols which delivered the desired products
(3p–3r) in high yields. Two representative hetero (aryl)
methanols such as pyridin-2-ylmethanol (2s) and
thiophen-2-ylmethanol (2t) have been found to smoothly
couple with N-uracil benzamidine, producing the
corresponding pyrimidouracils 3s and 3t in 77% and 64%
yields, respectively. However, the reaction of aliphatic
alcohols such as n-propanol and pivalyl alcohol with 1a
failed to yield even trace amounts of the expected
products. In the process, not even the starting material 1a
could be isolated. This phenomenon might be attributed
to simple aliphatic alcohols being more challenging in
respect of dehydrogenation than that of aryl methanols'
and the amidine undergoes a decomposition prior to
the dehydrogenation of alcohol. Hence, the rate of
dehydrogenative oxidation of alcohols is an important
factor in the formation of products.
FIGURE 1 Different catalysts used in the optimization
reaction
Cymene)]2 (Cat 6) was found to be the preferred catalyst,
providing the desired product 3a in 52% yield (Table 1,
entry 7). Screening of different bases such as K3PO4,
KOAc, Cs2CO3, Et3N, and DBU (Table 1, entries 8–12)
using [RuCl2(p-cymene)]2 as a catalyst in DMSO solvent
showed that the organic bases are less effective for the
formation of the product (Table 1, entries 11 and 12),
whereas Cs2CO3 gave
a significantly higher yield
(Table 1, entry 10). Thus, [RuCl2(p-cymene)]2 was
selected as preferred catalyst and Cs2CO3 as preferred
base. Next, screening of other solvents was performed.
The results indicated that tested solvents are less effective
compared with that of DMSO (Table 1, entries 13–16).
When the chosen catalyst, base and solvent were
employed, it was observed that the increase of reaction
time or reaction temperature did not have any significant
effect on this transformation (Table 1, entries 17 and 18).
However, when the catalyst loading was increased from
2 to 2.5 mol%, it resulted in an increased yield of the
product (85%) (Table 1, entry 19). But further rise in cata-
lyst loading did not have any effect on yield of the prod-
uct (Table 1, entry 20). Hence, the optimum reaction
conditions as far optimized are stated as follows: 2.5 mol
% of [RuCl2(p-cymene)]2, 1.5 equiv. of Cs2CO3, DMSO
(1 ml) as solvent, and at 110ꢀC (Table 1, entry 19).
After optimization of the reaction conditions, the
scope and limitations of this synthetic protocol were
tested. First of all, the reaction of different (hetero)aryl
methanols 2 with N-uracil benzamidine 1a, affording pyr-
imidouracils 3 was investigated. The results of the reac-
tions are summarized in Table 2. The synthetic protocol
has been found to work well with a range of (hetero)aryl
methanols (2a−2t) bearing ortho-, meta-, and para-, or
In order to extend the scope of this protocol, the reac-
tions of different N-uracil benzimidamides (1b–1h) with
benzyl alcohol (2a) were explored (Table 3). It was
observed that a variety of substituents including electron-
donating as well as electron-withdrawing groups on the
aryl ring of the N-uracil benzimidamide were tolerated
under the optimum reaction conditions. However, less
stable alkyl amidines such as acetamidine having a

DEBNATH ET AL.
5 of 9
TABLE 2 The reactions of N-uracil benzamidine (1a) with various hetero
(aryl) methanols (2)a,b
(Continues)
aReaction conditions: Substrate 1a (0.5 mmol), 2a (0.75 mmol), Ru-catalyst (2.5 mol%),
Cs2CO3 (0.75 mmol), DMSO (1 ml), 110ꢀC, 15 h.
bIsolated yield.
methyl at the R position (1h) could not yield the expected
product even with benzyl alcohol 2a. Notably, the para-
bromo-substituted pyrimidouracils 3h and 3w were
obtained in very good yields. It was delightful to find this
protocol's compatibility for the preparation of fluorine
substituted pyrimidouracils (3l and 3x), which have a
major influence on the pharmacological properties of a
drug.[35] The protocol also goes well with N-protected
uracils such as N-(1,3-dibenzyl uracilyl)benzimidamide
(1f) and N-(1-benzyl-3-methyl uracilyl)benzimidamide
(1g). When these substrates (1f and 1g) react with benzyl
alcohol (2a), the corresponding pyrimidouracils 3y and
3z are produced in 88% and 89% yields, respectively.
Interestingly, deprotection of these products[36] may
allow modification on the uracil moiety through N-alkyl-
ation/N-arylation or dehydrochlorination followed by
SNAr reaction. These synthetic modifications are particu-
larly interesting for the drug development purposes in
the pharmaceutical industry.[37]
In order to investigate the mechanism for the forma-
tion of products (3), some control experiments were per-
formed (Scheme 2). It was observed that the compound

6 of 9
DEBNATH ET AL.
TABLE 3 The reactions of various N-uracil amidines (1b–1h) with benzyl
alcohol (2a)a,b
aReaction conditions: Substrate 1a (0.5 mmol), 2a (0.75 mmol), Ru-catalyst (2.5 mol%), Cs2CO3
(0.75 mmol), DMSO (1 ml), 110ꢀC, 15 h.
bIsolated yield.
SCHEME 2 Some control experiments
4 was formed as major product (53%) when the reaction
was run for 5 h (Scheme 2a). Interestingly, when sub-
strate 4 was heated at 110ꢀC in absence of ruthenium cat-
alyst, it produced 3a in good yield along with 4 (12%)
(Scheme 2b). From these experiments, it was presumed
that the reaction proceeded through the formation of
4 and Ru-catalyst may not be essential for the oxidation
of 4 into 3a. Because the reactions were performed in
open air, aerial oxygen might play some important role
in the oxidation process. To confirm this, the compound
4 was heated at 110ꢀC for 15 h under N2 atmosphere in
absence of ruthenium catalyst, which resulted only 10%
of 3a (Scheme 2c). Moreover, a control reaction under N2
atmosphere was performed, which resulted 16% of 3a
and 66% of 4 (Scheme 2d). These reactions confirm that
molecular oxygen (O2) is necessary for the

DEBNATH ET AL.
7 of 9
SCHEME 3 Proposed mechanism for the
formation of pyrimido[4,5-d]pyrimidin-
2,4-diones
dehydrogenative oxidation of 4 into 3a. However, oxygen
balloon is not required for the supply of oxygen. In the
whole process, hydrogen and water molecules are pro-
duced as by products, confirming the greenness of the
protocol.[38]
4 | EXPERIMENTAL
4.1 | Instruments and reagents
All the chemicals and reagents were commercially avail-
able and purchased from Sigma-Aldrich, Alfa-Aesar,
Spectrochem, TCI Chemicals and used as received with-
out further purification. Silica gel, 60-120 and 230-400
mesh were purchased from Spectrochem, India and used
for chromatographic separation. Flash column chroma-
tography was performed over silica gel and 230-400 mesh.
TLC plates were purchased from Merck and used for
thin-layer chromatography (TLC). All solvents were dis-
tilled prior to use in extraction and purification purposes.
Melting points were measured on silicon oil bath using
On the basis of the previous accounts reporting the
progress of transition-metal catalyzed oxidation of alco-
hols[31,32] and boosted by control experiments, a probable
reaction mechanism for the generation of 3 is being
suggested in Scheme 3. Initially, the ruthenium-catalyzed
dehydrogenative oxidation of aryl methanol[31] formed
an aldehyde (A) which was then reacted with N-uracil
amidine 1a to produced intermediate azadiene 5.[39] The
intermediate 5 is then undergoes an intramolecular
cycloaddition reaction followed by a [1,5]-hydrogen shift.
These resulted in the formation of the intermediate
5,6-dihydropyrimido[4,5-d]pyrimidine 4 which on aerial
oxidation process yielded the desired product 3a.
open capillaries and are uncorrected. H and 13C NMR
1
spectra were recorded on a Bruker Ascend 400 MHz spec-
trometer (Bruker, Germany) at 400 and 100 MHz, respec-
tively using CDCl3 or DMSO-d6 solvents. Chemical shifts
values are given in parts per million (ppm, δ) with refer-
ence to tetramethylsilane (TMS) as internal standard.
Proton coupling patterns are described as follows: s, sin-
glet; d, doublet; t, triplet; m, multiplet; dd, doublet of
doublets; and dt, doublet of triplets. The coupling con-
stants are reported in Hertz (Hz). High-resolution mass
spectra (HRMS) were measured on a quadrupole time-
of-flight (Q-TOF) mass spectrometer (Make: Waters;
Model: Xevo XS) operated in the positive mode by apply-
ing an electrospray ionization (ESI) method.
3 | CONCLUSION
To summarize, an efficient and operationally simple pro-
tocol has been developed for the synthesis of densely
functionalized pyrimidouracils from inexpensive and eas-
ily available hetero(aryl) methanols and N-uracil
amidines by using commercially available [RuCl2(p-
cymene)]2 as a catalyst. Readily available alcohols were
employed as effective aldehyde precursors in the
oxidation-imination-cyclization transformation. The pres-
ented protocol has several advantages such as better
inherent stability of alcohols compared with aldehydes,
operationally simple, and starting materials are easily
accessible. This protocol is a significantly important com-
plement to the existing synthetic methodologies. Consid-
4.2 | General procedure for ruthenium-
catalyzed oxidative insertion of
hetero(aryl) methanols (2) into N-uracil
amidines (1) towards the synthesis of
pyrimidouracils (3)
ering
the
importance
of
pyrimidouracils
in
pharmacological field,[37] and material chemistry, this
synthetic strategy has the potential to be used in applica-
tions of not only in drug discovery but also in chemical
development projects.
N-Uracil amidine (0.5 mmol, 1.0 equiv.), hetero (aryl)
methanol (0.75 mmol), [RuCl2(p-cymene)]2 (0.0125 mmol,
8 mg) and Cs2CO3 (0.75 mmol, 244 mg) were added in an

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DEBNATH ET AL.
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added by syringe and the tube was sealed without
inserting any gas protection. The reaction mixture was
stirred in an oil bath at 110ꢀC for 15 h. After completion
of reaction, the mixture was cooled to room temperature.
The mixture was then stirred with ethyl acetate (10 ml)
and brine (10 ml) for 15 min. The aqueous layer was
extracted with ethyl acetate (2 × 10 ml). Finally, the com-
bined organic layers were washed with brine and dried
over anhydrous Na2SO4, filtered and concentrated. The
crude products were purified by either column chroma-
tography on silica gel (60–120 mesh) or flash column
chromatography (230–400 mesh) using a mixture of
hexane-ethyl acetate as the eluent to afford the title
compounds.
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ACKNOWLEDGMENTS
The author P. Debnath is thankful to Department of Sci-
ence and Technology (DST), New Delhi for financial
assistance (grant no. YSS/2015/001554). We are also
thankful to DST (New Delhi) for providing Bruker-400
spectrometer under DST-FIST program at Tripura Uni-
versity, Suryamaninar, Tripura, India.
AUTHOR CONTRIBUTIONS
Pradip Debnath: Conceptualization; data curation; for-
mal analysis; funding acquisition; investigation; project
administration; supervision. Gouranga Sahu: Data
curation; formal analysis; methodology. Utpal De: Data
curation; formal analysis; software.
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DATA AVAILABILITY STATEMENT
The data that support the findings of this study are avail-
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Pradip Debnath https://orcid.org/0000-0002-3429-6765
Gouranga Sahu https://orcid.org/0000-0001-9259-5184
Utpal C. De https://orcid.org/0000-0003-4870-5758
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How to cite this article: Debnath P, Sahu G,
De UC. Synthesis of functionalized pyrimidouracils
by ruthenium-catalyzed oxidative insertion of
(hetero)aryl methanols into N-uracil amidines.
Appl Organomet Chem. 2020;e6087. https://doi.org/
10.1002/aoc.6087