novel synthesis of hexestrol and its conjugates with acrylic acid derivative

27 Pages·2017·2.41 MB·English

WORLD JOURNAL OF PHARMACY AND PHARMACEUTICAL SCIENCES

Syed et al. World Journal of Pharmacy and Pharmaceutical Sciences

SJIF Impact Factor 7.421
Volume 7, Issue 9, 874-900 Research Article ISSN 2278 – 4357

NOVEL SYNTHESIS OF HEXESTROL AND ITS CONJUGATES WITH
ACRYLIC ACID DERIVATIVE

1*Syed Shah Abdus Salaam, 2Mohsina Abid, 3Dr. Katla Swapna and 4Priyanka
Polavarapu

1,2,4Assistant Professor, Department of Pharmaceutical Chemistry, Nizam Institute of
Pharmacy, Deshmukhi (V), Pochampally (M), Behind Mount Opera, Yadadri Bhuvanagiri
(Dist)-508284, Telangana, India.
3Department of Pharma.D, Bharat Institute of Technology-Pharmacy, Mangalpally,
Ibrahimpatnam, Telangana 501510, India.

ABSTRACT
Article Received on
25 June 2018, This current research work deals with novel synthesis of Hexestrol and

Revised on 15 July 2018,
it conjugates with Acrylic acid derivatives that can be potentially
Accepted on 05 August 2018
developed as anti-cancer agents. A Novel synthetic method has been
DOI: 10.20959/wjpps20189-12244
designed by using Mg and 10% Mncl for coupling. Considering these
2
anti-cancer properties Hexestrol (Hormonal anticancer drug) and
*Corresponding Author
(Tubulin inhibition) of Acrylic acid derivative (Combretastatin CA-4
Syed Shah Abdus Salaam
Assistant Professor, analouges), and we synthesized 3 conjugates through esterification of
Department of Hexestrol with Acrylic acids. To elucidate further SAR study on the
Pharmaceutical Chemistry,
chemistry, cytotoxic activity and probe the structural requirement for
Nizam Institute of
the potent anti-tumour activity of Hexestrol derivatives, a series of
Pharmacy, Deshmukhi (V),
novel Hexestrol Acrylic- acid conjugates were synthesized and send
Pochampally (M), Behind
Mount Opera, Yadadri for their in vitro cytotoxic activity in selected cancer cell lines.
Bhuvanagiri (Dist)-508284,
Telangana, India. KEYWORDS: Novel Synthesis, Hexestrol, Conjugates, Acrylic Acid
Derivative, Esterification.
INTRODUCTION
In simple terms, cancer is a group of more than 100 diseases that develop across time and
involve the uncontrolled division of the body’s cells.[1] Although cancer can develop in
virtually any of the body’s tissues, and each type of cancer has its unique features, the basic
processes that produce cancer are quite similar in all forms of the disease.[2,5] Cancer begins
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when a cell breaks free from the normal restraints on cell division and begins to follow its
own agenda for proliferation (Figure 1). All of the cells produced by division of this first
ancestral cell and its progeny also display inappropriate proliferation.[6] A tumor, or mass of
cells, formed of these abnormal cells may remain within the tissue in which it originated (a
condition called in situ cancer), or it may begin to invade nearby tissues (a condition called
invasive cancer). An invasive tumor is said to be malignant, and cells shed into the blood or
lymph from a malignant tumor are likely to establish new tumors (metastases) throughout the
body. Tumors threaten an individual’s life when their growth disrupts the tissues and organs
needed for survival.[7,10]

Figure 1: Begin of cancer.

Cancer is the primary leading cause of death in economically developed countries and the
second leading cause of death in developing countries.[11,15] About 12.7 million cancer cases
and 7.6 million cancer deaths are estimated to have occurred in 2008 worldwide with 56% of
the cases and 64% of the deaths in the economically developing world.[16,18] Cancer is a group
of disease characterized by uncontrolled growth and spread of abnormal cells, caused by both
external factors (tobacco, infectious organism, chemicals, radiation) and internal factors
(inherited mutation, hormones, immune conditions, mutation that occur from
metabolism).[19,21] These causal factors may act together or in sequence to initiate or promote
carcinogenesis. Ten or more years often pass between exposure to external factors and
detectable cancer. There are two broad categories of cancers: ‘carcinomas’, which develop in
the surface linings of organs and ‘sarcomas’, which appears in the cells of solid tissues, such
as muscles, bones and blood vessels.[22]
Cancer Therapies
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Cancer cells differ from their normal counterparts in a number of biochemical processes,
particularly during the control of cell growth and division.[5] Despite major breakthroughs in
many areas of modern medicine over the past 100 years, the successful treatment of cancer
remains a significant challenge today. Mainly, because it is difficult to discover novel agents
that selectively kill tumours cells or inhibit their proliferation without the general toxicity.
Treatment is aimed at removing the cancer cells or destroying them in the body with
medicines or other agents. The three most common types of cancer treatment are surgery,
radiotherapy and chemotherapy. Surgery is the primary treatment method where the tumour
mass and the associated lymph nodes are surgically removed for better patient survival.
Radiation therapy is used along with surgery and chemotherapy to improve the treatment.
However, it is used alone in early head and neck cancers. In chemotherapy, formulated
medicines are used to kill the cancer cells leading to the regression of tumour. Details of
chemotherapy are given below.[23,25]

MATERIAL AND METHODS
All chemicals were purchased from commercial suppliers and were purified when necessary.
All the compounds were confirmed by single spot in TLC after each step using cyclohexane
and ethyl acetate (98:2). All evaporation of solvents was carried out under reduced pressure
on Laborota-4000 rotary evaporator below 45oC. 1H NMR and 13C NMR spectra were
recorded on. Bruker, Avance 300 MHz. The samples were made in CDCl using tetra methyl
3
silane (TMS) as the internal standard and are given in δ scale, Chemical shifts are reported in
parts per million (ppm) downfield from tetra methyl silane. The standard abbreviations s, d, t,
q, m, dd, dt and brs refer to singlet, doublet, triplet, quartet, multiplet, doublet of a doublet,
doublet of a triplet and broad singlet respectively. Mass spectra were recorded on Micro Mass
VG-7070H mass spectrometer for EI. Infrared (IR) spectra are recorded on Perkin-Elmer
Infrared–683 or 1310 with NaCl optics. Spectra were calibrated against the polystyrene
absorption at 1610cm-1. Samples were scanned neat, KBr wafers or in chloroform as a thin
film. All reactions are monitored by thin layer chromatography (TLC) carried out on 0.25
mm E. Merck silica gel plates (60F-254) with UV light, iodine as probing agents. Acme
(India) silica gel (finer than 200 mesh) is used for flash chromatography. The reactions
wherever anhydrous conditions needed are carried out under the positive pressure of nitrogen
atmosphere using dry and freshly distilled solvents. All solvents and reagents were purified
by standard techniques. All evaporation of solvents was carried out under reduced pressure
on Buchi-RE-121 rotary evaporator below 45°C. Yield reported are isolated yields of
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material judged homogeneous by TLC and NMR spectroscopy. The names of all compounds
given in the experimental section were taken from ACD/Name, Version 1.0. The chemicals
and reagents (Table I) used in the present project were of AR and LR grade, procured
from Aldrich, Alfa aesar, Merck, S.D– Fine Chem. Ltd, and Sigma.

Table 1: List of chemicals used.
Acetic Acid (Glacial)
Acetic anhydride
Anethole
Chloroform
Cyclohexane
Dimethylsulfoxide
Dimethylformamide
Dichloromethane
Ethanol
Ethyl acetate
1-Hydroxybenzotriazole
Hexane
HBr
HI
Methyl alcohol
Magnesium Turnings
Mncl
2
N,N'-dicyclohexylcarbodiimide
Sodium sulphate
Sodium hydroxide
Sodium bicarbonate
Tetrahydrofuran
Triethyl amine

Synthetic Procedures
Novel Synthesis of Hexestrol

Step 1: Preparation of Anethole hydrobromide from Anethole.

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One tenth mole of Anethole (14.82 gm) is dissolved in 2.5 volume of THF; the solution is
kept at -15°C to -20°C. Add one mole of Hbr (80.9 gm) slowly. After addition of Hbr the
temperature was rise up to 0°C. The solution is then cooled again and maintained at -80°C
until used.

Step 2: Preparation of Dimethyl ether of hexestrol from Anethole hydrobromide.

Take 500ml two necked RBF add 0.2 mole magnesium (4.8 gm) and 0.01 mole Mncl (1.26
2
gm) in 400 ml anhydrous THF. Add step 1 product to it and stirr at room temperature for 24
hrs.

Then later the mixture was hydrolyzed with NHCO saturated solution and extracted with
3
ether (3×15 ml). The combined organic layers are dried over anhydrous Mg(SO ) and
4 2
concentrated under reduced pressure.

Step 3: Preparation of Hexestrol from Dimethyl ether of hexestrol.

A mixture of 500mg of Dimethyl hexestrol, 2cc Glacial acetic acid and 10cc Hydriodic acid
was heated at 135°C to 140°C for 2hrs. Water was then added and the product worked up in
ether. The ether extract had yellow colour which could be removed with sulfurous acid. The
extract was dried with anhydrous sodium sulphate and evaporated, leaving 0.4 gm of the
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product M.P (178°C -180°C). Recrystallisation from Benzene gave needles with M.P (184°C-
185°C).
Yield 0.39 gm, 87%

Synthesis of Substituted Acrylic acids

Synthesis of (E)-2,3-bis(4-methoxyphenyl)acrylic acid (C ).
1

A mixture of a (4.0 g, 20 mmol), b (4.0 g, 20mmol) and Triethylamine (20 mL) in Ac O
1 2
(100 mL) was refluxed at 120°C for 12h. After cooling, the mixture was evaporated
to dryness. The residue was diluted with aqueous NaOH for saponification. Then, the solution
was acidified with AcOH and extracted with CH Cl . The extract was dried over Na SO and
2 2 2 4
evaporated to dryness. The residue was crystallized from EtOAc-hexane to give
product compound C , 8.0 grams in 93% yield.
1
Yield= 8.0 g (93%).

Synthesis of (E)-3-(4-chlorophenyl)-2-(4-methoxyphenyl)acrylic acid (C ).
2

This compound C was prepared by the method described for C , employing a (5.0 g, 20
2 1 2
mmol) and b (4.0 g, 20mmol) afford the pure compound C , 8.0 grams in 93% yield.
2
Yield = 8.0 g (93%).

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Synthesis of (E)-2-(4-methoxyphenyl)-3-(4-nitrophenyl) acrylic acid (C ).
3

This compound C was prepared by the method described for C , employing a (5.0 g,
3 1 3
36.7mmol) and b (7.19 g, 36.7mmol) afford the pure compound C , 10 grams in 86% yield.
3
Yield = 86%

Synthesis of Hexestrol-AA Conjugates
Synthesis of Hex-AA Ester Compound (Hex-con ) (E)-4-(4-(4-hydroxyphenyl)hexan-3-
1
yl)phenyl 2,3-bis(4-methoxyphenyl)acrylate

Procedure
The compound Hexestrol (100 mg, 0.24 mmol) was dissolved in 10 mL of dried CH Cl ,
2 2
followed by addition of acrylic acid C (100 mg, 0.24 mmol), EDCI (88 mg, 0.48 mmol) and
1
HOBt (37 mg, 0.24 mmol). The reaction mixture was stirred at room temperature for 3 h. The
reaction mixture was washed with saturated solution of NaHCO and extracted with CH Cl
3 2 2
then dried over anhydrous Na SO and solvent evaporated under vaccum. The crude product
2 4
was purified by column chromatography with ethyl acetate/hexane (4:6) to afford pure
compound Hex-con , 162 mg in 83 yield.
1
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Synthesis of Hex-AA Ester compound (Hex –con ) (E)-4-(4-(4-hydroxyphenyl)hexan-3-
2
yl)phenyl 3-(4-chlorophenyl)-2-(4-methoxyphenyl)acrylate

Procedure
This compound Hex-con was prepared following the method described for the preparation
2
of the compound Hex-con , employing Hex (100 mg, 0.24 mmol), with acrylic acid C (100
1 1
mg, 0.24 mmol), EDCI (88 mg, 0.48 mmol) and HOBt (37 mg, 0.24 mmol) and the crude
product was purified by column chromatography with ethyl acetate/hexane (2:3) to afford
pure compound Hex-con , 160 mg in 82 yield.
2
Yield =160 mg (82).

Synthesis of Hex-AA Ester (Hex-con ) (E)-4-(4-(4-hydroxyphenyl)hexan-3-yl)phenyl 2-
3
(4-methoxyphenyl)-3-(4-nitrophenyl)acrylate

Procedure
This compound Hex-con was prepared following the method described for the preparation
3
of the compound Hex-con , employing Hex (100 mg, 0.48 mmol), with acrylic acid C (75
1 1
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mg, 0.24 mmol), EDCI (88 mg, 0.48 mmol) and HOBt (37 mg, 0.24 mmol) and the crude
product was purified by column chromatography with ethyl acetate/hexane (2:3) to afford
pure compound Hex-con , 141 mg in 82 yield.
3
Yield = 141 mg (82).

RESULTS AND DISCUSSION
Synthetic Studies
Considering the anti-cancer properties of HEX and AA, we succesfully synthesized 3
conjugates through esterification of HEX with AA acids. AA acids were prepared by
condensation of substituted phenyl acetic acid with substituted benzaldehyde. The condensed
products were isolated and characterized by 1H NMR and Mass analysis. The yields varied
from good to quantitative. The synthesized compounds were characterized through various
spectroscopic methods such as 1H NMR, Mass and IR which led to confirmation of the
synthesised compounds.

Work Flow: Our work was divided in to three steps
1. Scheme -1: Novel scheme for Synthesis of Hexestrol (HEX)
2. Scheme -2: Synthesis of Substituted Acrylic Acids derivatives
3. Scheme -3: Esterification of Hexestrol and substituted acrylic acids to give Hexestrol-
Acrylic acid conjugates.

Scheme
Scheme-1: Novel Synthesis of Hexestrol (Hex)

Step 1: Preparation of Anethole hydrobromide from Anethole.
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Step 2: Preparation of Dimethyl ether of hexestrol from Anethole hydrobromide using
Mg and 10% MnCl
2

Step 3: Preparation of Hexestrol from Dimethyl hexestrol

Scheme-2: Synthesis of Substituted Acrylic Acids.

Table 2: Synthesis of Substituted Acrylic Acids.
Compound No. R R R R R R
1 2 3 4 5
C H OCH H H OCH H
1 3 3
C H Cl H H OCH H
2 3
C H NO H H OCH H
3 2 3

Scheme-3: Synthesis of Hexestrol-Aa Conjugates.
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