Chemistry of Quinazoline & Its derivatives

1. Dr. Shakuntala Misra National
Rehabilitation University
Chemistry of Quinazoline & Its
Derivatives
SHIVAM GUPTA
M.Sc (Chemistry)
(4th Semester)

2. INDEX
 Introduction
 Chemistry of Quinazoline
 Synthetic Method
a) Metal- Catalyzed Reaction ( Copper Catalyzed
and Zinc Catalyzed reaction)
b) Reagent- Base Reaction
 Biological Activities ( Anticancer Activities and
Antibacterial Activities)
 Conclusion
 References

3. What is Quinazoline
A Heterocyclic Compound
With Benzene and Pyrimidine Ring
Having Anticancer, Antimicrobial,
Antiinflammatory, Antimalarial, Antialergatic
Activities
Having low water solubility

4. Introduction
Heterocyclic chemistry is a chemistry involving the heterocyclic
compound, which has atoms of at least two different element as number of
ring. The heterocyclic atoms may be inorganic, though the compounds
contains carbon atoms in the ring. The word hetero means “different from
carbon and hydrogen”.
Quinazoline is a compound formed by two fused six-member
aromatic rings: benzene and pyrimidine. In this two nitrogen atoms are
present in the quinazoline molecule at 1 and 3 positions that is why it is
also known as 1,3-diazanaphthalene. 1,3-Diazanaphthalene, commonly
known as quinazoline with molecular formula C8H6N2, is a very interesting
aromatic heterocyclic organic compound

5. Due to the presence of two nitrogen, the world ‘aza’ has been used in its
nomenclature There are various isomeric forms are also shown by
quinazoline as given below-
Quinazoline with substituents (other than those that are capable of
tautomerism, e.g. hydroxy and thiol) in positions 2 and 4 show the general
reaction and properties typical of quinazoline. This is because the two rings
have the full complement of pi- electrons to make them aromatic. The pi
electrons of the 3,4-double bond in quinazoline are highly delocalized and
confer on it an enhanced reactivity towards nucleophilic reagents

6. Quinazolines and its derivatives are classes of fused heterocycles that are of
considerable interest because of the diverse range of their biological
properties . Many substituted quinazoline and its derivatives possess a wide
range of bioactivities such as antimalarial, anticancer, antimicrobial,
antifungal, antiviral, antiprotozoan, anti-inflammatory, diuretic, muscle
relaxant, antitubercular, antidepressant, anticonvulsant, and many other
biological activities. Quinazoline and quinazolinone compounds are also
used in preparation of various functional materials for synthetic chemistry
and also present in various drugs molecules.

7. Chemsitry of Quinazoline & its Derivatives
The formation of quinazoline and its derivatives started most of the times
with anthranilic acid and its derivatives. In these methods, carbon dioxide
was used for the building block of carbon atom for the formation of
pyrimidine ring, under solvent free conditions.
Quinazolines when carry a substituent in the benzene ring
and not in heterocyclic ring are termed as Benz-substituted quinazolines.
This group is characterised by lack of satisfactory methods of preparation.
All known Bz-substituted quinazolines are low melting crystalline solids,
rather unstable and easily affected by oxidation, reduction and hydrolysis.

8. The simplest member is quinazoline first prepared by Gabriel[1] in 1903 by
mild alkaline ferricyanide oxidation of 3,4- dihydroquinazoline.
In 1905 Riedel obtained a patent describing only one method for the direct
synthesis of quinazoline from o-nitrobenzaldehyde and formamide to form
o-nitrobenzylidene diformamide. Reduction of this with zinc and dilute
acetic acid gave quinazoline in good yield. Later improvements in Riedel's
original procedure to obtain up to 65% overall yield has been reported. This
is the best method of obtaining quinazoline.

9. Quinazoline is a cyclic-conjugated 10π electron system with a resonance
energy value of 127.2 kJ mol− 1 and an aromaticity index of 143. The observed
dipole moment of quinazoline in benzene is 2.2 D and this value is in good
agreement with the calculated value (2.55 D).
Quinazoline behaves chemically like its pyrimidine counterpart with the
exception that quinazoline is more basic due to electrophilicity of the C-4-
position. Fusion of the benzene ring with the pyrimidine rings results in altered
reactivity of both the rings in quinazoline. The benzene ring is deactivated
toward electrophilic attack due to the electron-withdrawing effect of the
pyrimidine ring. There is significant electron depletion at C-2 and C-4 but only
minor depletion at C-5, C-6, C-7, and C-8.

10. Synthetic Method
Metal- Catalyzed Reaction
 Copper- Catalyzed Reaction:-
Aryl ether, alkyl ether, aryl amine,
alkyl amine, aryl sulfide, alkyl sulfide, etc., which are all very important
structural fragments in many chemical molecules, have an urgent need for
better synthetic methods. Classical copper-catalyzed Ullmann reaction has been
widely studied due to its significant role in this regard. It raised attention from
many chemists and became one of the focal point in organic chemistry research
in recent years. Sang et al. reported a copper catalyzed sequential Ullmann N-
arylation and aerobic oxidative C-H amination for the convenient synthesis of
indolo [1,2-c] quinazoline derivatives.[2]

11. In their research, 2-(2-halophenyl)-1H-indoles and (aryl)methanamines
were adopted as raw materials to generate corresponding Schiff base via
Ullmann reaction. Then gas as oxidant, 3 equiv K2CO3 as base, DMSO as
solvent and 10 mol% Cu(OAc)2 as catalyst were revealed as the optimum
conditions, to conduct aerobic oxidative C-H amination under 110°C.
(Mechanism Followed by Ullmann Reaction)

12. The synthesis of 1,3-diazanaphthalene derivatives is catalyzed by different copper
compounds, such as copper bromide, copper chloride, copper acetate, and copper
iodide. Out of these, metallic salt copper iodide is shown to be most effective in
terms of yield. [3]
Zhang et al. (2014) [4] reported a scheme for the synthesis of the
target molecule containing quinazoline moiety by copper iodide catalyst. This
reaction starts when ortho-bromophenyl alkyl/aryl aldehyde derivatives react with
5-aminopyrazoles in the presence of copper iodide as catalyst and potassium
carbonate as a base in dimethylformamide the reaction is shown below-

13.  Zinc- Catalyzed Reaction:-
Zinc is the first capable metal found to
participate in water-phase Barbier reaction. It could catalyze the allylation
of carbonyl and carbonyl compounds as well as participate in the
benzylation of carbonyl and some special alkylation. Apart from
participating in the carbon-oxygen double bond Barbier reaction, Zinc
could also be applied to carbon-nitrogen double bond Barbier reaction,
such as the allylation of imine and α-amino aldehyde. In short, Zinc could
stably exist in water phase with relatively strong activity.
• In the synthetic research of
imidazo [1,2-c] quinazoline derivatives designed by Shi et al.[5] , 2-(2-
nitrophenyl)-1H-imidazoles was reduced by Zn/H+ to 2- (2-amino phenyl)-
1H-imidazoles , which then reacted with isothiocyanates to get intermediate

14. . Cylization of compound by nucleophilic attack of the nitrogen atoms on C =
S group was afford the intermediates . Finally, the desired products were
obtained from by losing of H2S.

15. Low-valent titanium reagents, which aroused an increasing concern in the
field of organic synthesis, could effectively improve the coupling of
carbonyl compounds[6] . A synthetic method assisted by low-valent
titanium reagent was reported by the same group mentioned above[7] . In
this synthesis, a series of quinazoline derivatives were afforded by adopting
anhydrous THF as solvent and the TiCl4-Zn system as reducing agent.
Several representative synthetic routes were selected

16. Reagent- Base Reaction
In 1905 Riedel obtained a patent describing only one method for the direct
synthesis of quinazoline from o-nitrobenzaldehyde and formamide to form
o-nitrobenzylidene diformamide. Reduction of this with zinc and dilute
acetic acid gave quinazoline in good yield. Later improvements in Riedel's
original procedure to obtain up to 65% overall yield has been reported. This
is the best method of obtaining quinazoline.

17. Alkvl or Arvl-quinazolines
Ammonia reacts readily with o-acylamino benzaldehydes or phenyl
ketones to give high yields of the corresponding quinazoline. When
substituted amino ketones are available, this constitutes the best method of
obtaining quinazoline nucleus substituted with an alkyl or aryl group in the
2- or 4-position. Thus, when o-acetamidoacetophenone is heated in a sealed
tube with alcoholic ammonia, gives nearly quantitative yields of 2,4-
dimethylquinazoline.[8]

18. Rodriguez et al.[9] synthesized quinazoline derivatives by using a
photochemical reaction, which proved to be a very good concept in terms
of yield. In this reaction, 2-amino-acetophenone was used as a starting
compound and condensed with hydroxylamine and benzaldehyde , which
converted into an oxime compound . This oxime was further cyclized under
a mercury lamp to gave the excellent yield of the target compound.

19. Present Work:-
A simple, efficient and general method has been developed for the
synthesis of new substituted 4-amino-benzoquinazoline derivatives
from 4-hydroxy benzoquinazoline with various amines by using
sulphuric acid as a dehydrating agent afforded the products in
excellent yield when compared to 4-chlorobenzo quinazoline with
various amines under reflux condition using 2-propanol as solvent.
In the present study, we performed the synthesis and biological
evaluation of some libraries of these compounds[10].We explored
the possibility of synthesizing Benzo [g]quinazolin4-yl-(4-chloro-
phenyl)-amine libraries, The whole work is summarized below-

21. Biological Activities
 Anticancer Activities:-
Cancer is one of the serious
health problems in front of human population both in developed as well
as developing countries. Cancer is a term used for diseases in which
abnormal cells divide without any control and may attack other tissues
also. Cancer is a devastating disease and it can spread to other parts of
the body through the blood and lymph systems. In present scenario
numbers of people suffering from cancer are increasing day by day and
necessitate the need of good protection from cancer with reduced
adverse effects.

22. A large number of chemotherapeutic molecules have been
developed in last few years which are used for the treatment of
cancer that includes DNA- alkylating agents and antimitotic agents.
Quinazolinones are among the most beneficial heterocyclic
compound from both synthetic and medicinal chemistry aspects.
Most of the researchers involved in synthesis of quinazolinone and
evaluation of its anticancer property. The structural designs of new
hybrid quinazolinones moiety have attracted a great deal of attention
because of their diverse chemical reactivity and excellent anticancer
activities .

23. Chen and his co-workers[11] have reported new hybrid quinazolinone
derivatives. This synthesized compound exhibit in vitro antiproliferative
activity when treated against human acute myelogeneous leukemia (AML).
It was found that it reduces the expression of Myc by Western blot analysis.
These results show that compound is a most potent with an IC50 value of
5.09 M against proliferation of A549 cells.

24. Anti- Bacterial Activities:-
The development of constant
growth of bacterial resistance against the traditional antibiotics such as
penicillin and tetracycline has motivated a continuing search for new
classes of heterocyclic compounds with novel modes of anti-bacterial
activity. One of the most frequently known heterocyclic molecules in
medicinal chemistry is 4(3H)-quinazolinone with wide applications
including antibacterial and anti-insecticidal activities. The literature survey
revealed that antimicrobial activities of quinazolinone motifs increase by
substituting different heterocyclic ring at the third position. The
quinazolinone nucleus containing compounds have a broad spectrum of in-
vitro and their in-vivo chemotherapeutic activity.

25. Lin and his co-workers[12] have designed and synthesized new
quinazolinone nucleus containing compound and evaluated its
antimicrobial activities against four strains of gram-positive
bacteria(Staphylococcus aureusand Bacillus cereus)and gram-negative
bacteria (Escherichia coli and Pseudomonas aeruginosa). The synthesized
compound exhibited significant activity towards Grampositive bacterial,
Gram-negative bacterial. The MIC (0.8–3.3lg/mL) and MBC (2.6–7.8lg/
mL) value for this compound are very nearest to those of norfloxacin,
chlorothalonil, and fluconazole which indicate that the compound is
stronger antimicrobial agent.

26. Conclusion
In this present scenario, the importance of Quinazoline and its derivatives
are increasing day by day. Over the past few decades, more effort has been
established into searching of better drugs with minimal side effects. Herein
various synthetic procedures are discussed for the synthesis of
quinazolinone and quinazoline derivatives. There are various structural
modification around the fused ring of quinazoline and its derivative mainly
quinazolinone subsequently evaluate are for their usefulness in treating
various disease conditions.

27. In different types of disease activities like Anticancer activities,
Antimicrobial activities, Antifungal activities , Antibacterial activities,
Antiviral activities etc, Quinazoline and its derivatives proved themselves
as an effective and essential drug.
In general, quinazolinone and quinazoline
derivatives are known to possess wide range of activities. A specific
activity depends on the substituent present at an appropriate position of
quinazoline. These substitutions are mainly done through Nucleophilic
Substitution, Nucleophilic addition, Oxidation, Reduction, Intermolecular
Cyclization, Photochemical Reactions.

28. Lab Work
Prepration of Anthranilic acid :-
Dissolve 7.5gm NaOH in 40ml
water and cool in ice bath to about 273k and then add 2.1ml Br2 solution to
it. To this solution add 6g phthalamide and 20ml 10% NaOH solution, then
heat the solution for 5-10 minutes till pthalamide dissolves.
Melting Point :- 145-150 degree celcius
.

29. Prepration of Quinazoline derivative from
Anthranilic Acid:-
Reaction of anthranilic acid in pyridine
with benzoyl chloride at room temperature afforded the starting material 2-
(4-phenyl)-4H-benzo[d] [3,1] oxazine-4-one.[12]
Melting Point:- 125-130 degree celsius

30. REFERENCES
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2. Sang P, Xie YJ, Zou JW, Zhang YH: Copper-catalyzed sequential Ullmann N-
arylation and aerobic oxidative C-H amination: aconvenient route to indolo[1,2-
c]quinazoline derivatives. Org Lett 2012, 14:3894–3897
3. Kundu NG, Gopeswar C: Copper-catalysed heteroannulation with alkynes:a
general and highly regio- and stereoselective method for the systhesisof (E)-2-(2-
arylvinyl) quinazolines. Tetrahedron 2011, 57:6833–6842
4. Gao, L.; Song, Y.; Zhang, X.; Guo, S.; Fan, X. Copper-catalyzed tandemreactions
of 2-bromobenzaldehydes/ketones with aminopyrazoles toward thesynthesis of
pyrazolo [1, 5-a] quinazolines. Tetrahedron Lett., 2014, 55, 4997-5002
5. Shi DQ, Rong SF, Dou GL, Wang MM: One-pot synthesis of imidazo[1,2-
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31. 8. shodhganga.inflibnet.ac.in › 16...PDFsynthesis of some new quinazoline derivatives.
– Shodhganga(2019)
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32. THANK YOU