chapter 2 synthesis of compounds...
TRANSCRIPT
CHAPTER 2 SYNTHESIS OF COMPOUNDS RELATED
TO 4,5 CIS-5-SYTRYL-2-0XO-OXAZOLIDINE-4-CARBOXYLIC ACID
The great power of the aldol reactions lies in the ability to generate and
use structurally defmed enolates. The renaissance that has occurred in the aldol
reactions in the l~st two-three decades has been mainly due to the development
of methods for the formation and use of preformed enolates. The simplest
enolates to prepare are those associated with lithium and magnesium, and there
now exists a considerable literature documenting certain aspects of lithium and
magnesium enolate aldol chemistry. Asymmetric aldol reactions are potentially
of great value in synthetic chemistry. Consequently, the asymmetric aldol
condensations continue to stimulate much thought from a synthetic and
mechanistic point of view1-S• Over the past few years, several chiral enolate
systems have been reported to exhibit high level of diastereoselectivity in aldol
reactions 1,2. Moreover, metal assisted aldol condensations6,7 have received
much synthetic and mechanistic attention and shown tremendous potential in
asymmetric synthesis. Its use in the preparation of chelation and nonchelation
controlled aldol adduct has been amply demonstrated in the literature8,9.
The synthesis of 4,5-cis-5-styryl-2-oxo-oxazolidine-carboxylic acid, the
active molecule, which has been discussed in detail in the previous chapter, is
also based upon aldol condensation via lithium enolate generationiO•
It is well-established fact that the bioavailability of a drug has
implication on its dose; Compounds, which are both poorly, absorbed or
rapidly metabolized, show weak activity and are required to be given in higher
amounts. Lipophilicity of compound helps in retaining the molecule in the
body stores for extended period, thus increasing the systemic availability. With
a view of increase the bioefficacylbioavailability of the parent molecule 4,5-
cis-2-oxo-oxazolidine-5-styryl:-4-carboxylic acid, some new compounds related
to this and its precursor 2 have been prepared. Present segment of the thesis
will describe various standard synthetic methodologies, utilized in the synthesis
of these molecules.
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In a previously reported procedure describing synthesis of the precursor
of 4,5-cis-2-oxo-oxazolidine-5-styryl-4-carboxylic acid, lithium dienolate of
ZGlyOEt (1) was generated in THF at -78°C using 2.2 eq. of LDA (generated
in situ from diisopropylamine and n-butyl lithium). Addition of 1.4 equivalents
of cinnamaldehyde (excess) to the stirred solution of lithium dienolate at -78°C
under the nitrogen atmosphere gave after usual workup and chromatographic
separation on silica gel, two products 2 and 3
ZN,./"'....COOEt H
(1)
LOA (2.2 eq.) •
ee OLi
.. ~OEt LiNZ e
~H
Ph~COOEt
OH ) Ph~CHO Ph~COOEt
NZ H
NZ H
(2) Major (3) Minor
SCHEME 1
Owing to hazardous nature of BuLi, which has to be used for generation
of LDA in situ, we have used LiHMDS for enolate generation albeit with a
little loss of stereoelectivity in enolate reaction. Column chromatographic
purification of the mixture over silica gel using hexane-ethyl acetate as eluant
followed by fractional crystallizations, gave pure 2 as off white crystals. A pure
fraction of 3 was obtained only, after purifying the enriched fraction using
HPLC, and was identified by PMR. PMR spectra of these two stereo isomers 2
and 3 have almost similar patterns except the chemical shifts of 2H and 3H. In
2 both 2H and 3H appeared together as multiplet centered at () 4.5, whereas in 3
2H and 3H appeared separately as multiplet at () 4.45 and 4.72 respectively.
23
ZN~COOEt H
@:H (i) LiHMDS (2.2 eq.) • Ph~' COOEI
............ '-.. _CHO ' '" (ii) Ph' '-.."y"
THF, 65-700C H~
anti (2) major
SCHEME 2
+
OH
Ph~COOEI NZ H
syn (3) minor
Apart from this, proton of the ester function also showed slight comparative
chemical shift difference. Protons of the ester-ethyl group in 2 appeared at 8
1.12 (t) and 8 4.09 (q) (1=7 Hz), while in 3 these peaks were at 1.20 (t) and
4.15 (q). Similar chemical shift differences were also observed for 4H (8 6.08
and 6.12 for 2 and 3 respectively). However the 5H proton appeared as a
doublet at 86.60 (J=17 Hz) in both the isomers. All aromatic protons appeared
as unresolved broad singlet centered at 7.20 in case of both 2 and 3. Their IR
spectra showed strong absorptions at 1740 and 1700 cm-' due to the c=o of
ester and Z group respectively. Whereas absorption band at 3400 cm-' in both 2 and 3 was due to OH group. The mass spectra of both 2 and 3 showed
molecular peaks at MlZ 369 (1f"), 359 (M-18) and 91 (CH2Ph). To make an
unambiguous stereochemical assignment in 2 and 3, the major isomer was
subjected to alkaline hydrolysis using NaOH at 0-5°C. The compound 4
obtained after usual workup was characterized by its spectral data, which
indicated that cyclization has occurred.
24
~H
Ph~COOEt
(2)
(3)
NH Z
NaOH (3 eq)
THF : H20 (55:45)
NaOH (3 eq)
THF : H20 (55:45)
SCHEME 3
o
OANH
Ph~COOH H H
(4)
o
OANH
~'-..... ~COOH Ph~ ~ ... ~
H R (5)
PMR studies have indicated that styryl and carboxylic group has cis
stereochemistry while 5 showed trans stereochemistry of styryl and carboxylic
group. When mixture of 2 and 3 was hydrolyzed under identical conditions, a
mixture of cis and trans isomer was obtained which could not be separated by
fractional crystallizations. PMR spectra of 4 showed a doublet at 8 4.40 (J=9
Hz) due to 4H and a triplet at 5.35 (J=6 & 9 Hz) due to 5H. The styryl pattern
was same as in the parent compound 2 i.e. double doublet at 6.10 (J=6 and
J=17 Hz) and a doublet at 8 6.72 (J';17 Hz). The signal for aromatic protons in
4 also appeared as broad singlet at 8 7.31. The IR spectrum of 4 showed strong
absorption at 1700-1740 cm-1 due to carboxylic and oxazolidinone groups. The
mass spectrum showed molecular peaks at mlz 233 (~) and 189 (~-C02)'
The PMR of mixture of cis (4) and trans (5) isomer showed two sets of
doublets at 8 4.15 (J=4.5 Hz) for 5 and 8 4.40 (J= 9 Hz) for 4 due to 4H.
Triplets at 8 5.08 (J=4.5Hz, J=6 Hz) for 5 and 8 5.35 (J=6 Hz, J=9 Hz) for 4
due to 5H. The coupling constants in case of trans oxazolidinone derivatives
have been reported to be 5 Hz 12 • As the oxazolidinone 4 has hs= 9 Hz. This
25
has been assigned 4,5-cis-stereochemistry and named as cis-5-styryl-2-oxo-
oxazolidine-4-carboxylic acid. Similarly Oxazolidinone 5 having 4.5 Hz
coupling between 4H and 5H, was assigned trans-stereochemistry. Based upon
this evidence the major isomer 2 has been retrospectively assigned anti-
configuration. This is also supported by literature evidences 13-15, where 3 H of
similar syn compound appears slightly downfield in comparison to that of anti
isomer.
A similar set of reactions was carried out by condensing
cinnamaldehyde with various alkyl, arylalkyl esters of ZGlyOH, hippuric acid,
substituted hippuric acids and sarcosine giving rise to respective aldol products
in varying yields.
Rr" + R3
R,· R2 (6) H H (7) H H (8) H H
(9) H H
(10) ,H H (11) H' H
(12) H H (13) H H (14) H H (15) H -OMe (16) -OMe -H (17) -OMe -H
H
H H
H H H
-OCOCH3 -H -H
R4 -OCH2Ph
-Ph -OCH2Ph
-Ph
-Ph -Ph
-Ph -CeH4(CI)
-CeH4(OMe) -OCH2Ph
-Ph CeH4(F)
~H Ph~cOOMe
Zf\J Me
(18)
26
CH3 -CH2CH2CH
CH3 CH3
-CH2CH2CH CH3
-CH3 CJ*.l
-G-CH3 CA"3
-(CH2)s-CH3 -C2Hs -C2Hs -C2Hs -C2Hs -C2Hs
The varIOUS esters used for enolate generation were prepared by
refluxing appropriate acids and alcohols (2.5 eq.) in presence of at as catalyst
using toluene as solvent16 with azeotropic removal of water, while methyl ester
of sarcosine was prepared via diazemethane esterification 17. All the products
obtained as a consequence of aldol condensation under the described reaction
conditions, were predominantly the erythro adduct like 2. Compound 10
showed chemical shifts at 8 4.87 (J=7 Hz) and 5.09 (J= 7 & 6 Hz) as doublet
and double doublet corresponding to 2H and 3H while a dd at 8 6.15 (J=6 Hz,
J=16 Hz) and a doublet at 8 6.7 (J=16 Hz) were due to 4H and 5H .. The
multiplet in the region from 8 7.2-7.5 was assigned to aromatic protons.
Another downfield doublet at 8 7.8 (J= 9 Hz) corresponded to 2 protons ortho
to c=o. Usual peaks for -OCH3 was obtained as singlet at 8 3.84. Mass
spectrum of 10 showed a peak at mJz 325, which was equivalent to molecular
ion. In IR spectrum of 10 a strong peak at 1730 corresponded to C=O. When
compound 10 was made to undergo alkaline hydrolysis using NaOH and
THFlMeOH, Product 19 was obtained as uncyclized aminoacid.
~H ~H
Ph~cOOM_e_--.. PhCN
IIH o
Ph~COOH PhCNH
II o (10) (19)
SCHEME 4
Apart from these various a-amino acid derivatives related to 4 discussed
previously, various acyl, arylalkyl, alkylalkanoate ester derivatives of 4,5-cis-2-
oxo-oxazolidine-5-styryl-4-carboxylic acid 4 were also synthesized as prodrug,
by capping its carboxylic group, designed with the aim to improve oral
absorption and subsequent systemic availability of 4. It is well documented in
the literatUre that these esters are hydrolyzed to parent acid by non-specific
27
esterases present in the serum and various tissues from rat, dog and man. Since
simple alkyl or aryl esters are hydrolyzed rather more slowly especially in
human organism, hence easily labile special type of groups have been
considered for masking the carboxylic groups18,19.
In effort to synthesize these esters of 4 various coupling agents and
reaction conditions were tried. DCC20 the most common coupling agent, alone
and in conjunction with HOBT21 or DMAP22 was employed under the usual
reaction conditions but no product was obtained, even starting material 4 could
not be recovered. PMR data of crude reaction material clearly indicated the
destruction of oxazolidine ring.
DCC/DCC-DMAP • No Product DCC-HOBTIBOP-CI
Again reaction could not be succeeded while using (Bis(2-oxo-3-
oxazolidinyl) phosphinic chloride (BOP-Cl)i3, owing to the instability of the
oxazolidinone ring of 4 might be due to active ~ elimination of ring proton , the
more common methods could not be succeeded. We therefore attempted the
nucleophilic esterification of 4. The methodology involves alkali salt formation
and its reaction with appropriate alkyl halide to give esters. Thus 4 was treated
with various acyl, alkyl, aryl alkyl bromides (1.1 eq.) in the presence of
NaHC03 and dry DMF (solvent). Product in each case was obtained as white
solid with excellent yields.
28
20
21
22
23
RBr (1.1 eq.)
NaHC03 (3 eq.) Dry eMF
R = -CH2C6Hs 0 II
R= -CH2CC6Hs 0 II
.R= -CH2COC2Hs 0 II
R = -CHCOC2Hs I CH3
SCHEMES
PMR of these esters were on'the same pattern as of 4) with no change in
the relative stereochemistry of C4 and C5 stereo centres. PMR data of 20
showed slightly downfield shifts of 4H and 5H, in comparison to the
corresponding shifts in 4, which were at () 4.59 and () 5.4. Though peak
corresponding to 5H was present as multiplet due to merger of peak for NH.
Styryl pattern and chemical shift positions of protons were quite similar to
parent compound which were at () 6.0 as dd and 6.7 as doublet for CH=CH·Ph
and CH=CH·Ph respectively. Singlet at () 7.2·7.3 corresponded to Ar-H as
multiplet. Also a peak at () 5.1 integrating for two protons clearly indicated
addition of OCH2Ph group. Mass spectram showed the peaks in abundance at
mlz 324 (M+ 1 t and 279 (M-C02). Presence of strong absorption peaks at 1756
cm') and a broad hump from 3135-3227 cm') were assigned to c=o and NH
respectively. Compound 24 showed very interesting PMR spectra due to
presence of additional gem coupling. A multiplet at () 4.5 was due to -OCH2
and 4H. At () 5.15 a triplet is due to 5H (J=6 Hz, J=9 Hz). A triplet at () 5.27
29
(1=10 Hz) for -CH=Cfu was suggestive of additional gem coupling. A
multiplet at 8 5.8 corresponded to CH-CH2• Styryl pattern was similar to the
parent compound. A broad peak at 87.2 was due t? Ar-H. In mass spectra peak
at m/z 274 and 230 were due to (M+ It and loss of CO2 respectively. IR
showed intense band at 1751 corresponding to CO while a hump from 3000-
3200 was due to NH.
In another scheme, the styryl double bond of 4 and related esters was
reduced over PdlC catalyst in ethanot24 by bubbling hydrogen gas for 15
minutes only. Consistent higher yield was obtained in these reductions.
Another route to synthesize 26 was the direct nucleophilic substitution reaction
with appropriate bromide (1.1 eq.) in the presence of sodium bicarbonate and
dryDMF.
(25)
25 R = H
Pd/C, ethanol ~
H2 passed, 15 min
26 R = -CH2C2H5
SCHEME 6
C6H5CH2Br, NaHC03 ~
Dry DMF, stirring overnight
(26)
PMR of 25 and related esters were a bit complicated due to additional
couplings as a result of reduction of styryl double bond. In 25 a multiplet at 0
2.0 and 8 2.79 corresponded to CfuCH2Ph and CHrCfu-Ph respectively.
Appearailce of multiplets instead of triplets was indicative of restricted rotation
30
across the -CHr -CH2Ph bond. However,exact J values could not be measured
due to complexity of multiplets. Chemical shift positions at 0 4.26 as doublet
(1=9 Hz) and at 0 4.65 as multiplet with .1=9 Hz, J=4 Hz, were for 4H and 5H
respectively. These J values again indicated the cis stereochemistry across the
4C and 5C of ring. A broad hump at 0 5.4 corresponded to NH. A complex
multiplet from 0 7.1-7.3 was due to Ar-H. Mass spectrum of 25 showed peaks
at rnJz 236, 192 and 91 corresponding to (M+lt, (M-C02t and (CH2Pht,
respectively. A strong absorption peak in the IR at 1747 cm -\ was due to C=O.
Another modification in the esters 20, 22, 24 was done via protecting the NH
group of oxazalidone ring with methyl group. This was accomplished by
treating esters with methyl iodide, sodium bicarbonate and dry DMF. The rate
of reaction as well as yield of the product significantly improved when KHC03
was used in. plac;e of NaHC03. Extremely dried conditions were applied
throughout the course of reaction' to avoid the· hydrolysis of esters. PMR
spectra of these N-methylated esters were similar to the parent compound
except minor differences in the chemical shift positions.
27R=~ o II
28 R = -CH2COC2Hs 29 R = -CH2C6Hs
SCHEME 7
PMR spectrum of compound 27 showed a singlet at 0 2.4 corresponding
to NMe while a doublet at 0 4.43 with J=9 Hz and a triplet at 0 5.2 with J=9 Hz
corresponded to 4H and 5H. J value of 9 Hz clearly defines that relative
31
configuration across C~ and C1 remained unaltered i.e. the carboxylic and
styryl group were cis. A doublet at 8 4.5 was for -OCH2 (1=5 Hz) while a
doublet at 8 5.1 with J=10 Hz and a mUltiplet at 8 5.6 were corresponding to
CH=Cfu and CH=CH2 respectively. Chemical shifts of styryl protons were
exactly th~ same as in the parent 4 i.e. a double doublet at 8 6.0 (1=6 Hz, J=17
Hz) and a doublet at 8 6.7 (1=17 Hz) for CH=CH-Ph and CH=CH-Ph
respectively. A broad unresolved singlet at. 8 7.1 corresponded to aromatic
protons. Mass spectrum of 27 showed peaks in abundance at rnIz 288
equivalent to (M+lt and 244 for (M-C02t. A strong absorption peak at 1759
em-lin the IR spectrum was suggestive ofC=O group.
2.1 EXPERIMENTAL
The melting points were taken in a Remi M.P. apparatus containing
sulfuric acid bath and are uncorrected. lR spectra (KBr, Ymax em-I) were
recorded on Shimadzu 8201 PC (4000-350 em-I) spectrophotometers. PMR
spectra (CDCh unless stated otherwise) were run on a Bruker DPX 200 (200
MHz FT NMR) spectrophotometer using Tetramethylsilane as the internal
standard (Chemical shifts in 8 and J values in Hz). Mass spectra were recorded
on a Jeol D-300 (El) and Jeol SX-102 (EVCIIF AB) mass spectrophotometers.
HPLC of the samples was preformed on Water . Associates liquid
chromatograms Model 244 (Porasil or bondpack C-18 Reverse Phase Column).
The homogeneity of. the compounds was routinely checked by TLC on silica
gelG.
Synthesis of Ethyl-N-Carbobenzyloxyglycinate (1)
Ethylglycinate HCI (20 g) was dissolved III a precooled (0-5°C)
magnetically stirred mixture of water (20 mL) and ether (200 mL). To this
cooled solution, triethyl amine (22 mL) was added, followed by dropwise
addition of carbobenzyloxy chloride (32 mL). The reaction mixture was stirred
for 2 hours at room temperature. The· ether layer was separated and washed
32
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successively with dil. HC} (1%, 50 mL), dil. Na2CO) (3x20 mL) water (4x50
mL), dried (Na2S04) and concentrated to furnish an oily material. The crude
product was distilled under high vaccuum to give pure 1, yield 22 gms, B.P.
160°C/~ 1 mm.
PMR (CDCI3, 200 MHz)
8 1.15 (3, t, J=7 Hz, -OCH2-Cfu), 3.80 (2, d, J=6 Hz, NHCfu), 4.05 (2, q, J=7 Hz, -OCfuCH3), 5.0 (2, s, Cfu-Ph), 5.55 (1, h, N-H), 7.20 (5, s, Ar-H)
Synthesis of ethyl-E-2,3-anti-2(benzyloxycarbonylamino )-3-hydroxy-5-phenyl-pent-4-enolate-l (2) and ethyl-E-2,3-Syn-2 (benzyloxycarbonyl amino )-3-hydroxy-5-phenylpent-4-enolate-l (3)
In a 200 mL capacity R.B. flask (flame dried and cooled under nitrogen
atmosphere) equipped with a temperature probe, graduated dropping funnel and
magnetic stirrer, was taken LIHMDS solution (1 M, in CH2Ch, 100 mL). To it
was added dropwise, a solution of ZglyOat (8 gms) in THF over a period of
one hour at -60° to 70°C. Stirring of the reaction mixture was continued till 3
hours. A solution of cinnamaldehyde (4.6 gms) in 20 mL ofTHF was added to
the reaction mixture at -65°C over a period of 1 hour. The temperature of the
reaction mixture was maintained at -60 to 65°C and the stirring was continued
for additional 3 hours. Solution of conc. HCI (25 mL) made in distilled water
(75 mL) and added to the reaction mixture for 45 minutes to quench the
reaction. Quenched reaction mixture was left as such till the separation of
aqueous and organic layer. The organic layer was separated and washed thrice
with saturated prime solution. Aqueous layer was also extracted twice with
ethyl acetate and combined organic layer was dried (Na2S04) and concentrated
on a rotavapour under reduced pressure. Product was crystallized from ethyl
acetate, hexane system. Solid was filtered through sintered funnel. Total yield
of the product was 4.2 gms. M.P. 92°C.
IR(KBr) 1700, 1740, 3000, 3300, 3400 cm-)
PMR (200 MHz) 81.12 (3, t, J=7 Hz, =OCHrCfu), 3.35 (1, bh, OID,
33
Mol. formula
Mass
4.09 (2, g, -OClliCH3 J=7 Hz), 4.55 (2, m, 2H, and 3H), 5.02 (2, s, CfuPh), 5.78 (1, d, J=9 Hz, N-H), 6.08 (2, dd, J=6 & 17 Hz, 4H), 6.60 (1, d, J=17 Hz, 5ID, 7.20 (5, bs, Ar-H).
C2,H23NOs mJz 237,91
The mother liquor was chromatographed over silica gel column in
hexane using 5% ethylacetate as eluant to remove unreacted cinnamaldehyde.
Now the fraction containing 2 and 3 were subjected to HPLC (Prep) separation
over reverse phase C-18 column using MeOH: H20 (50:50) to give a small
amount 070 mg) of pure 3 as viscous oil.
IR(Neat)
PMR (CDCh, 200 MHz)
1700, 1740, 3000, 3450, 3500 cm-'
8 1.20 (3, t, J=7 Hz, -OCH2C!b), 4.15 (2, q, J=7 Hz, -OClliCH3), 4.45 (1, m, 2H), 4.72 (1, m, 312), 5.00 (2, s, ClliPh), 5.50 (1, Ph, OH), 5.70 (1, d, J=9 Hz, N-H), 6.12 (2, dd, J=6 and 17 Hz, Cill, 6.60 (1, d, J=17 Hz, 5ID, 7.20 (s, bs, Ar-H)
Synthesis of 4,5-cis-5-styryl-2-oxo-oxazolidine-4-carboxylic acid (4)
Compound 2 (5 gms) was dissolved in 55 mL of THF and water (30
mL) and NaOH (1.8 gm) was added to it at O°C with continuous stirring. The
reaction mixture was stirred for 30 minutes at 0-5°C and then allowed to warm
upto room temperature (0-5 hour). On disappearance of starting material,
excess THF was concentrated, the residue acidified with dil. HCl and extracted
with ethyl acetate (3xlOO mL). The organic layer was washed with brine
solution (3x50 mL), dried over Na2S04 and concentrated to give after
crystallization 3 as white solid.
Yield: 2.4 gIns, M,P, 145-150°C
IR(KBr)
PMR (DMSO,d6)
1700-1740,3000,3400 cm-'
04.40 (1, d, J=9 Hz, 4-H), 5.35 (1, t, J=7 Hz, 5ID, 6.10 (1, dd, J=6, 17 Hz, Ph-CH=CID, 6.70 (1, d,
34
Molecular formula
Mass
·1=17 Hz, Ph-CH=CH), 7.31 (5, bs, Ar-H)
C'2H"N04
m1z 233 (Ml, 189,44
4,5-Trans-5-styryl-2-oxo-oxazolidine-4-carboxylic acid (5)
When a mixture of 2 and 3 (1.0 gm) was hydrolyzed in an identical
procedure as described for 4, the product after fractional crystallization was
obtained. Yield 0.310 g.
8 4.15 (1~ d, 1=4.5 Hz, 4H), 5.10 (1, t, 1=4.5 Hz, 5ill, 6.10 (1, dd, 1 = 6 & 17 Hz, Ph-CH=CH), 7.31 (5, bs, Ar-ill·
Synthesis of E-2,3 anti 2-(benzyloxy carbonyl)amino-3-hydroxy-5-phenyl-pent-4-enoic acid benzyl ester (6)
The compound was synthesized from benzyl-N-carbo-
benzyloxyglycinate (2 gms), cinnanaldehyde (0.83 gms, 0.9 eq) and LIHMDS
(14 inL O.IM solution, 2 eq.) and THF (125 mL using the same procedure as
described for 2. Crude product was purified over silica gel column in 20%
ethylacetate:hexane system and crystallized in the same system. Total yield 1.8
gm (58%), M.P. 80°C.
IR(KBr)
PMR (DMSO.D6)
Mass
Molecular formula
1724, 3115-3500 cm-'
05.1 (4, s, OCHr C6Hs), 5.2 (1, m, 2ill, 5.67 (1, m, 3ill, 6.0 (1, q, 4H, 1=6 Hz, 1=16 Hz), 6.58 (1, d, 5R, 1=16 Hz), 7.1-7.4 (10, m, Ar-ill
m1z431 (~)
C26R2SNOs
35
Synthesis of E-2, 3-anti 2-benzo~lamino-3-hydroxy-S-phenyl-pent-4-enoic acid benzyl ester (7)
Compound was prepared from benzyl N-benzoyl glycinate (2 gms),
cinnamaldehyde (0.93 gms, 0.9 eq), LIlIMDS (15.6 mL, 1M solution, 2 eq)
and THF (125 mL) using the same method as for 2. Crude product was purified
over silica gel column in 30% ethyl acetate hexame system. Yield - 2 gms
(63%), M.P. 147°C.
IR(KBr) PMR(DMSO)
Mass
Molecular formula
1656, 1735,3000-3500 cm- I.
05.10 (1, m, 2H), 5.2-5.38 (3, m, 3H, OCH2C6Hs), 6.1 (1, q, 4H, J=6 Hz, J=16 Hz), 6.59 (1, d, 5H, J=16 Hz), 7.0-7.86 (8, m, Ar-H), 7.82 (2, d, ortho to C=O group J = 9 Hz).
mJz 402 (M+), 384 (M-H20t
C2sH23N04
Synthesis of E-2,3-anti 2-benzyloxycarboxylamino-3-hydroxy-S-phenyl-pent-4-enoic acid-3-methyl butyl ester (8)
Compound was synthesized from 2-methyl butyl-N-(carbobenzyloxy)
glycinate(l gm), cinnamaldehyde (0.53 gm) and LIHMDS (9 mL, 1 M in
THF), THF (90 mL) using the same procedure l;lS described for 2. Compound
was purified over silica gel in ethyl acetatelhexane system. Compound obtained
as white solid. M.P. 89°C, Yield 0.53 gm (51 %).
IR(KBr) PMR (DMSO.D6)
Mass
Molecular formula
1640,1732,3100-3300 cm- I
00.88 (6, d, CH(Cllih J=7 Hz), 1.49 (3, m, Cfu-CH-(CH3)2), 4.21 (1, d, 2H, J=7 Hz), 4.25 (2, m, OCfuCH2), 5.1 (2, s, OCH2Rh), 5.3 (1, dd, 3H, J=6 Hz, J=7 Hz), 6.4 (1, dd, 4H, J=6 Hz, J=17 Hz), 6.8 (1, d, 5H, J=17 Hz), 7.1-7.3 (10, m, Ar-H).
MlZ 412 (M+lt
C24H29NOs
36
Synthesis of E-2,3-anti-2-benzoylamino-3-hydroxy-5-phenyl-pent-4-enoic acid-300m ethyl butyl ester (9)
Compound was prepared from 2-methyl butyl N-(benzoyl)-glycinate (1
gm), cinnamaldehyde (0.47 gm, 0.9 eq) and LIHMDS (8 ml, 2 eq), THF (90
ml) using the same procedure as described for 2.
Compound was purified over silica gel column in ethyl acetatelhexane
system. M.P. 75°C, yield 0.5 gm (53%).
IR(KBr)
PMR(DMSO)
Mass
Molecular formula
1643, 1734,3000-3400 cm-)
80.90 (6, d, CH(Clli)2, J=6 Hz), 1.52 (3, m, -Cfu-CH-{CH3)2), 4.11 (1, d, 2H, J=7 Hz), 4.27 (2, m, OCfu-CH2), 4.87 (1, bh, NH), 5.04 (1, dd, 3H, J=7 Hz, J=6 Hz), 6.3 (1, dd, 4H, J=6 Hz, J=17 Hz), 6.71 (1, d, 5H, J=17 Hz), 7.2-7.5 (8, m, Ar-H), 7.8 (2, d, H ortho to C=O J = 9 Hz )
MlZ 382 (M+lt,364 (M-18t
C23H27N04
Synthesis of E-2,3-anti-2-benzoylamino-3-hydroxy-5-phenyl-pellt-4-enoic acid methyl ester (10)
The compound was prepared from methyl N-benzoyl glycinate (5 gms),
cinnamaldehyde (2.8 gms, 0.9 eq), LiHMDS (48 mL, 1M solution) and THF
(250 mL) using the same procedure as described for 2. Crude product was
crystallized without purification over silica gel column using ethylacetatel
hexane system. Total yield 4.4 gms, m.p. 141°C.
IR(KBr)
PMR(DMSO)
Mass
Molecular formula
1750, 3130, 3328 em-)
83.84 (3, s, OClli), 4.87 (1, d, 2H, J=7 Hz), 5.09 (1, dd, 3H, J=7 Hz, J=6 Hz), 6.15 (1, dd, 4H, J=6 Hz, J=16 Hz), 6.7 (1, d, 5H, J=16 Hz), 7.2-7.5 (8, m, Ar-H), 7.8 (2, d, H ortho to c=o J = 9 Hz).
MlZ325 (Ml C)9H)9N04
37
Synthesis of E-2,3-anti-2-benzoylamino-3-hydroxy-5-phenyl-pent-4-enoic acid test-Butyl ester (11)
Compound was prepared from t-Butyl N-(Benzoyl) glycinate (1 gm),
cinnamaldehyde (0.47 gm, 0.9 eq), LIH1vIDS (8 mL, 1M solution) in THF (90
mL) using the same procedure as was for 2. Product purified from silica gel
column and obtained as white solid. M.P. 104°C, yield 0.53 gms (53.2%).
IR(KBr) PMR(DMSO)
Mass
Molecular formula
1644, 1765,3000-3340 cm- I
8 1.5 (9, s, -C(CIL)3), 2.0 (1, s, OID, 4.8 (1, m, 2ID, ,5.02 (1, m, 3ill, 6.2 (1, dd, 4H, 1=6 Hz, J=17 Hz), 6.9(1, d~ 5H, J=17 Hz), 7.1-7.4 (8, m, Ar-H), 7.8 (2, d,H ortho to C=O). mJz 368 (M+)
C22H26N04
Synthesis of E-2,3, anti-2-benzoylkamino-3-hydroxy-5-phenyl-pent-4-enoic acid nonyl ester (12)
Compound was synthesized from Nonyl-N-(Benzoyl)-glycinate (1 gm),
cinnamaldehyde (0.9 eq), LiHMDS (2 eq) and THF 90 mL using the same
procedure as was used for 2. Proc.l.uct purified over silica gel column in 15%
ethyl acetate in hexane system. Product obtained as white solid. M.P. 105°C,
yield 49%.
IR(KBr)
PMR (CDCI3, 200 MHz)
Mass
Molecular formula
1633, 1744,3297,3416 cm- I
80.87 (3, t, CH3, J=6 Hz), 1.25 (12, m, (Cfu)6CH3, 1.64 (2, m, OCH2Cfu), 4.17 (2, t, OCH2, J=6 Hz), 4.8 (1, m, 2ID, 5.06 (I, m, 3H), 6.22 (1, dd, 4H, J=6 Hz, J=17 Hz), 6.9 (1, d, 5H, J=17 Hz), 7.l-7.5 (8, m, Ar-ill, 7.83 (2, d, H ortho to C=O).
mJz 437 (Ml, 419 (M-18t
C27H3SN04
38
Synthesis of E-2,3-anti-2-(2-chloro-benzoylamino)-3-hydroxy-5-pheny1-pent-4-enoic acid ethyl ester (13)
Compound was synthesized from ethyl N-(2-chloro benzoyl) glycinate
(2 gms), cinnamaldehyde (1.1 gms), LIHMDS (19 mL, 1 M solution), THF
(125 mL) using the same methodology as was used for the preparation of 2.
Product was obtained as gel. Yield: 1.6 gms (44%).
IR(KBr)
P:MR (CDCh, 200 MHz)
Mass Molecular formula
1635, 1746,3000-3500 cm-)
() 1.29 (3, t, CH2Clb J=7 Hz), 4.29 (2, q, ClhCH3 J=7 Hz), 4.8 (1, bm, 2H), 5.05 (1, m, 3H), 6.24 (1, dd, 4H, J=6 Hz, J=16 Hz) () 7.3-7.64 (9, m, Ar-H), 7.66 (1, d, H ortho to C=O)
mJz 374 (Ml, 356 (~-18)
C2oH2oCIN04
Synthesis of E-2,3,anti-3-hydroxy-2-( 4-methoxy-benzoylamino )-5-phenyl-pent-4-enoic acid ethyl ester (14)
C~mpound was prepared from ethyl N-(-4-methoxy benzoyl) glycinate
(2 gms), cinnamaldehyde (1.06 gm), LiHMDS (17.9 mL 1 M solution), THF
(125 mL) using the same procedure as described for 2. Crude product was
purified over silica gel column in 30% ethyl acetatelhexane system. Product
obtained as white crystals_ M_P. 125°C, total yield 1.8 gms (54%).
IR(KBr)
P:MR (CDCI3, 200 MHz)
Mass Molecular formula '
1650,1730,3200 cm- I
() 1.2 (3, t, CH2Clb, J=6 Hz), 3.72 (3, s, OClb), () 4.31 (2, q, Clh-CH3, J=6 Hz), 4.87 (1, M, 2H), 5.04 (1, M, 3H), 6.16 (1, dd, 4H, J=6 Hz, J=16 Hz), 6.69 (1, d, 5H, J=16 Hz), 7.05 (2, d, H ortho to OMe J = 8 Hz), 7.2-7.3 (5, M, Ar-H), 7.9 (2, d, H ortho to C=O J=9Hz)
mJz369 (~)
C21H23NOs
39
Synthesis of E-2,3-anti-2-benzyloxy carbonyl amino-3-hydroxy-4-(3-methoxy-4-propionyloxy-phenyl)-but-3-enoic acid ethyl ester (15)
The compound was prepared using ZglyOrt (5 gms), autoxymethoxy
cinnamaldehyde (4.6 gms, 1 eq.), LIHMDS (41 mL, 1 m solution) in 250 mL
of THF according to the same procedure as described for 2. Product directly
crystallized from ethylacetateihexane system and yellowish white crystals
obtained. Total yield: 4~9'gms, M.P. 132°C.
IR(KBr)
PMR (CDCh, 200 MHz)
Mass ,
Molecular formula
1710, 1764,3069,3289,3455 cm- l
8 1.24 (3, t, CH2CH3, J=7 Hz), 2.3 (3, s, COC[b), 3.8 (3, s, OMe), 4.1 (2, q, CH2CH3 J=7 Hz), 4.6 (2, M, 2H and 3ill, 5.1 (2, s, OC!h), 5.7 (1, d, NH, J=7 Hz), 6.1 (1, dd, CH=CHPh, J=6 Hz, J=17 Hz), 6.6 (1, d, CH=CHPh, J=17 Hz), 6.9 (3, m, Protons ortho to OMe and OCOCH3 and meta to OCOCH3), 7.2-7.3 (5, M, Ar-ill.
mlz 458 (M), 440 (M-18t
C24H27NOg
Synthesis of E-2,3-anti-2-benzoylamino-3-hydroxy-5-(-2-methoxy-phenyl)-pent-4-enoic acid ethyl ester (16)
Compound was synthesized from ethyl N-(benzoyl) glycinate (2 gms),
o-methoxy cinnamaldehyde (1.4 gms, 0.9 eq), LIHMDS (19.5 mL, 2 eq) and
THF, (125 mL) using the same procedure as described for 2. Crude product was
purified over normal silica gel column using 20% ethylacetate in hexane
system. Total yield 1.6 gm (50%). M.P. 118°C.
IR(KBr)
PMR (CDCI3, 200 MHz)
Mass
1643, 1747,3421 cm- l
81.16 (3, t, CH2CH3 J=7 Hz), 3.8 (6, s, OMe), 4.14 (2, q, CH2CH3 J=7 Hz), 4.9 (1, m, 2H), 5.0 (1, m, 3ill, 6.2 (1, dd, 4H, J=6 Hz, J=17 Hz), 6.89 (1, d, 5H, J=17 Hz), 7.1-7.5 (8, m, ArH), 7.84 (2, d, H ortho to C=O, J=7 Hz).
mlz 356 (~+1), 338 (~+18), 307 (338-0Me)
40
Molecular fonnula
Synthesis of E-2, 3-anti-2- (3-fluoro-benzoylamino )-3-hydroxy-5-( -2-methoxy phenyl)-pent-4-enoic acid-ethyl ester (17)
Compound was synthesized from N-(fluorobenzoyl) glycyl ethyl ester (2
gms), 2-methoxy cinnamaldehyde (1.19 gms, 0.9 eq), LIHMDS (17.3 mL, 1M
solution) and THF (125 mL) using the same procedure as used for 2. Crude
product was purified on nonnal silica column in 40% ethylacetate:hexane
system. Purified fraction was crystallized from ethylacetate-hexane. Total yield
1.92 gms (60%), M.P. = 110°C.
IR(KBr)
PMR (CDCh, 200 MHz)
Mass
Molecular fonnula
1643,1741,3319 em-I
o 1.27 (3, t, CH2Cfu, J=7 Hz), 3.80 (3, s, OCH3),
4.28 (2, q, ClliCH3, J=7 Hz), 4.9 (1, m, 2ID, 5.03 (1, m, 3ID, 6.23 (1, dd, J=6 Hz, J=17 Hz, 4H), 6.8-7.6 (9, m, Ar(F)-ID, Ar(OMe)H, SID.
rnJz 386 (~)
C21H22FNOs
Synthesis of E-2,3-anti-2-(Benzyloxycarboxyl-methyl-amino )-3-hydroxy-5-O-tolyl-pent-4-enoic acid methyl ester (18)
Compound was prepared from methyl ester of Z sarcosine (2 gms), 0-
methoxy Cinnamaldehyde (1.2 gms, 0.9 eq), LIHMDS (16.8 mL, 2 eq, 1M
solution) and THF (125 mL) using the same procedure as described for 2.
Product was purified over silica gel column but was obtained as isomeric
mixture of 2 diastereoisomers. HPLC separation gave rise to one isomer in
abundance. Yield (28%).
IR(KBr)
PMR (CDCI3, 200 MHz)
1699,1741,3441 em-I.
02.9 (3, s, NMe), 3.67 (3, s, OMe), 4.28 (1, d, 2H, J=7 Hz), 4.8 (1, dd, 3H, J=7 Hz, J=6 Hz), 5.13 (2, s, ClliPh), 6.15 (1, dd, 4H, J=6 Hz, J=17 Hz), 6.87 (1, d, 5H, J=17 Hz), 7.1-7.3 (9, m, ArID.
41
Mass mJz 391 (~-18)
Synthesis of E-2, 3-anti-2-benzoylamino-3-hydroxy-5-phenyl-pent-4-enoic acid (19)
Compound was prepared by hydrolysing 10 (5 gms) with NaOH (3 eq)
and THF/water using the same procedure as was used for synthesis of 4. Yield
2.3 gms, M.P. 115°C.
!R(KBr)
PMR(CDCI3)
Mass
Molecular formula
1639, 1760,3000-3300 cm- l
84.9 (1, m, 2H), 5.0 (1, m, 3H), 6.2 (1, dd, 4H, J=6 Hz, J=17 Hz), 6.8 (1, d, 5H, J=17 Hz), 7.1-7.3 (8, m, Ar-H), 7.6 (2, d, H ortho to C=O J = 8 Hz).
mJz 310 (M+)
ClsH 17N04
Synthesis of 4,5-cis-2-oxo-5-styryl-oxazolidine-4-carboxylic acid benzyl ester (20) ,
Compound 4 (2 gms), Benzyl bromide (1.3 gms, 1 eq), and sodium
hydrogen carbonate (3 eq, 2.16 gm) were dissolv~d in dry DMF (50 mL) in an
oven dried 100 mL capacity round bottomed flask. Reaction mixture was
continuously stirred overnight. Completion of reaction was monitored by TLC
in 50:50 ethylacetate:hexane system. Reaction mixture was poured in 200 ml of
water. Extraction was performed from aqueous layer with ether (200 mL)
thrice. Organic layer was dried over sodium sulfate and concentrated. Product
was crystallized in ehtylacetate-hexane system. The product obtained as white
solid. M.P. 140°C, Yield 2 gms (74%).
IR(KBr)
PMR (CDCh, 200 MHz)
Mass
1597, 1756,3135-3227,3425 cm- l
84.59(1, d, 4H, J=9 Hz), 5.1 (2, s, OCfu), 5.4 (2, rn, 5H & NH), 6.0 (1, dd, CH=CH-Ph, J=6 Hz, J=17 Hz), 6.73 (1, d, CH=CH-Ph, J=17 Hz), 7.2-7.3 (10, rn, Ar-H).
mJz 324 (~+1), 279 (M-C02t 42
Molecular formula
4,5-cis-oxo-5-styryl-oxazolidine-4-carboxylic acid-2-oxo-2-phenyl ethyl ester (21)
Compound was prepared from 4 (2 gms), phenacyl bromide (1 eq, 1.5
gm), sodium hydrogen carbonate (3 eq, 2.16 gm) and dry DMF (50 mL) in 100
mL capacity R.B. flask using the same procedure as described for 20. Product
was obtained as cream ish crystals. M.P. 175°C, Yield 2.3 gms (76%).
IR(KBr)
PMR (CDCh, 200 MHz)
Mass
Molecular formula
1602, 1753,3000-3400 cm- I
04.7 (1, d, 4H, J=8 Hz), 5.38 (2, d, OClli, J=7 Hz), 5.4 (1, t, 5H, J=8 Hz), 5.6 (1, bs, NH), 6.39(1, dd, CH=CH-Ph, J=6 Hz, J=17 Hz), 6.84 (1, d, CH=CH-Ph, J= 17 Hz), 7.2-7.6 (8, m, Ar-H), 7.84 (2, d proton ortho to C=O J = 8 Hz).
MlZ 307 (M-C02/
C20HI7NO5
Synthesis of 4,5-cis-oxo-5-styryl-oxazolidine-4-carboxylic acid-ethoxycarbonyl methyl ester (22)
Compound was prepared from 4 (2 gms), ethylbromoacetate (1 eq, 0.73
gm) sodium hydrogen carbonate (3 eq, 2.16 gms) were taken in dry DMF (50
mL) in an 100 mL capacity RBF. Reaction mixture was continuously stirred
overnight. Procedure is same as used for 20. Product obtained after
crystallization as white solid. M.P. 65°C, Yield 1.3 gms (48%).
IR(KBr)
PMR (CDC13, 200 MHz)
Mass
Molecular formula
1599, 1747,3409 cm- I
o 1.25 (3, t, CH2Clli, J=7 Hz), 4.2 (2, q, ClliCH3,
J=7 Hz), 4.65 (3, m, OClli and 4H), 5.44 (2, m, 5H & NH), 6.28 (1, dd, CH=CH-Ph, J=7 Hz, J=16 Hz), 7.1 (1, d, CH=CH-Ph, J=16 Hz), 7.28 (5, m, Ar-H).
m/z320 (M+l/, 289 (~-C2Hs), 276 (M-44/
C16H17N06
43
Synthesis of 4,5-cis-2~oxo-5-styryl-oxazolidine-4-carboxylic acid 1-ethoxycarbonylethyl ester (23)
The compound was synthesized from 4 (2 gms) sodium hydrogen
carbonate (3 eq, 2.16 gm) and2-bromoethylpropionate (1 eq, 1.5 gm) and dry . ,.
DMF (50 mL) uSing the same procedure as described for 20. Compound was
obtained as white solid. M.P. 130°C, Yield 1.5 gm (53% yield).
IR(KBr) PMR (CDCI3, 200 MHz)
Mass
Molecular formula
1600, 1750,3000-3400 cm-)
8 1.2-1.3 (6, m, CH-Cfu, CH2-Cfu), 4.2 (2, q, Clk-CH3, J=7 Hz), 4.67 (1, d, 4H, J=8 Hz), 5.05 (2, m, OCH2CH3), 5.6 (1, t, 5H, J=8 Hz), 6.16 (1, dd, CH=CH-Ph, J=6 Hz, J=17 Hz), 6.79 (1, d, CH=CH-Ph, J=17), 7.2-7.4 (5, m, Ar-H)
rnJz 333 (Ml, 293 (M-44t
C17H)9N06
Synthesis of 4,5-cis-2-oxo-5-styryl-oxazolidine-4-carboxylic acid allyl ester (24)
The compound was synthesized from 4 (2 gms), sodiumhydrogen
carbonate (3 eq, 2.16 gms) and allyl bromide (1 eq, 1.2 gms) and DMF (50 mL)
using the same procedure as described for 20. Compound was obtained as
white crystals. M.P. 130°C, Yield 1.5 gms (53% yield).
IR(KBr) PMR(CDCh,200 MHz)
Mass
Molecular formula
1607, 1751,3000-3400 cm-)
84.5 (3, m, O-Clk & 4H), 5.15 (2, t, CH=Clk, J=10 Hz), 5.27 (1, s, NH), 5.4 (1, t, 5H, J=8 Hz), 5.8 (1, m, CH=CH2), 6.1 (1, dd, CH=CHPh, J=17 Hz), 6.79 (1, d, CH=CHPh, J=17 Hz), 7.2-7.3 (5, m, Ar-H).
rnJz 274 (M+ It, 230 (~-C02) +
C)sH)sN04
44
Synthesis of 4,S-cis-2-oxo-S-phenylethyl-oxazolidine-4-carboxylic acid (2S)
Compound was prepared by mild reduction of styryl bond of 4. 2 gms of
4 was taken in a hydrogenation bottle and dissolved in dry ethanol. To it was
added Pd/C catalyst (40 mg). To this mixture was passed hydrogen gas for
strictly 15 minutes. Solution was filtered over filter paper. Residue was nicely
washed thrice with ethanol. Combined organic layer was concentrated. Solid
was recrystallized in ethanol/ethyl acetate system. Compound was obtained as
white crystals. M.P. 125°C, yield 1.88 gms (94%).
IR (KBr)
PMR (CDCI3, 200 MHz)
Mass
Molecular formula
1599, 1747, 3351 cm-)
82.0 (2, m, Clli-CH2-Ph), 2.79 (2, m, CH2-Clli-Ph), 4.26 (1, d, 4H, J=9 Hz), 4.65 (1, m, 5H, J=9 Hz, J=4 Hz), 5.4 (1, bn, NH), 7.1-7.3 (5, m, Ar-ID
m/z 236 (~+ 1), 192 (M-C02t, 144,91
C12H\3N04
Synthesis of 4,S-cis-2-oxo-S-phenyl-cthyl-oxazolidine-4-carboxylic acid benzyl ester (26)
Compound was prepared from (2S) (1 gm), benzyl bromide (1 eq, 0.7
gms), NaHC03 (2.15 gms) and dry DMF (50 mL) using the same procedure as
described for 20. Product after crystallization was obtained as white solid. M.P.
130°C, yield: 52%.
IR(KBr)
PMR(CDCh,200 MHz)
Mass·
Molecular formula
1601, 1759,3144,3264 cm-)
8 1.8 (2, m, Clli-CHrPh), 2.7 (2, m, CHrClli-Ph), 4.39 (1, d, 4H, J=9 Hz), 4.7 (1, td, 5H, J=9 Hz, J=6 Hz), 5.1 (2, dd, OCH2, J=11 Hz), 7.74 (10, m, Ar-ID m/z 325 (Ml, 181 (M-C02t C)9H )9N04
45
Synthesis of 3-methyl-2-oxo-5-styryl-oxazolidine-4:-carboxylic acid allyl ester (27)
In a 100 ml capacity R.B. Flask, was taken 1 gm of extremely dried 24,
anhydrous K2C03 (3 eq., 1.5 gm) and dried DMF (30 mL). 2.5-3 eq. of methyl
iodide was added to the reaction mixture very slowly and with cooling.
Reaction mixture was stirred overnight. Completion of reaction was monitored
with TLC in 40% ethyl acetatelhexane system. Reaction mixture was poured in
200 mL of slightly acidic water. And immediately the pH of aq. layer was
maintained to neutral with 2N HCl. Aqueous layer was extracted 3-4 times
with 200 ml ether. Combined organic layer was dried over sodium sulfate,
concentrated. Product was purified over normal silica gel column in 25% ethyl
acetatelhexane system. Compound was obtained as white solid. M.P. 81°C,
yield 56%.
IR(KBr)
PMR (CDCh, 200 MHz)
Mass
Molecular formula
1653, 1759,3015 cm-'
82.9 (3, s, NMe), 4.43 (1, d, 4H, J=9 Hz), 4.5 (2, d, OClli, J=5 Hz), 5.1 (2, t, CH=Clli, J=lO Hz), 5.2 (1, t, 5H, J=9 Hz), 5.6 (1, m, CH=CH2), 6.0 (1, dd, CH=CH-Ph, J=6 Hz, J=17 Hz), 6.7 (1, d, CH=CH-Ph, J=17 Hz), 7.3 (5, bs, Ar-H).
mJz 288 (M+ 1 t, 244 (M-C02t C'6H 17N04
Synthesis of 4,5-cis-3-methyl-2-oxo-5-styryl-oxazolidine-4-carboxylic acid ethoxycarbonylmethyl ester (28)
Compound was prepared from dried 22 (1 gm), methyl iodide (2.5 eq),
potassiumbicarbonate anhydrous (3 eq.) and DMF (30 mL) using the same
procedure as described for 27. Product was purified over silica gel column in
25% ethylacetatelhexane system. Compound was obtained as white solid. M.P.
100°C, yield 52%.
46
IR(KBr) PMR (CDCI3, 200 MHz)
Mass
Molecular formula
1596, 1749,3025 cm-1
8 1.25 (3, t, CH2Ctb, J=7 Hz), 2.98 (3, s, NMe), 4.2 (2, q, ClLCH3, J=7 Hz), 4.2 (1, d, 4H, J=8 Hz), 4.6 (2, s, OClL), 5.2 (1, t, 5H, J=8 Hz), 6.2 (1, dd, CH=CH-Ph, J=6 Hz, J=17 Hz), 8 6.8 (1, d, CH=CH-Ph, J=17 Hz), 7.2-7.3 (5, m, Ar-H).
mlz 334 (M+lt, 290 (M-C02t
C21Hl9NOs
Synthesis of 4,5-cis-3-methyl-2-oxo-5-styryl)-oxazolidine-4-carboxylic acid benzyl ester (29)
Compound was prepared from 20 (1 gm), methyl iodide (2.5 g, 1 mL),
K2C03 (3 ~q, 1.3 gm) and very dried DMF (30 mL) using the same procedure
as described for 27. Compound was obtained as white crystals. M.P. 150°C,
yield: 0.5 gm (48% yield).
IR(KBr)
PMR (CDCh, 200 MHz)
Mass
Molecular formula
1655, 1762,3022 cm-1
82.9 (3, s, NMe), 4.43 (1, d, 4H, J=8 Hz), 5.1 (2, s, OClL), 5.2 (1, dd, 5H, J=8 Hz, J=6 Hz), 6.0 (1, dd,
. CH=CH-Ph, J=6 Hz, J= 17 Hz), 6.6 (1, d, CH=CH-Ph, J=17 Hz), 7.1-7.3 (10, m, Ar-H).
mlz 338 (M+lt, 294 (M-Co2t
C2oHl9N04
2.2 BIOLOGICAL ACTIVITY
The compounds synthesized in this chapter were evaluated for their anti-
ulcer activity.
In pylorous ligated rats
A modified shay rat preparation was employed. The rats were deprived
of the regular food and allowed water ad lib for 48 hours before the
experiment. They were kept singly in cages with wire netting floor to prevent
coprophagy. The pylorus was ligated under ether anaesthesia. On recovery
. 47
from anesthesia the compound was administered either supartaneously or
intravenously, the control animals receiving normal saline. Five animals were
used at each dose level. Four hours after the drug administration the animals
were sacrificed. The ulc~r activity of the test compound was fuged by the
alteration in gastric juice and the ulcer index. The gastric juice was collected,
centrifuged and the volume of the supernatant was measured. The acidity was
determined by liberating the supernatant with 0.1 N NaOH using Topfers
reagent and phenophthalein as indicators for free and total acidity. The stomach
was opened, washed with luke warm saline and the ulcer lesions were
classified through macroscopic examination as described by Admi et aP5.
0 0 = No lesion
+ 1 = 1 or 2 haemorrhagic spots
++ 2 more than 2 haemorrhagic spots
+++ 3 = more important haemorrhagic areas
++++ 4 = imperforated ulcer
I I I II 5 = perforated ulcer
In organ chambered frog stomach mucosa
Whole frog stomach was used for the experiment. 0.1 mM histamine
was used as physiological secretagogue. One hour acid collection was done of
each: i. basal acid secretion ii. histamine stimulated iii. Acid secretion in the
presence of 5 mg of each compound (applied twice) plus histamine, i.v.
Compound· withdrawn but histamine containing acid secretion. Control
experiments block alrriost complete acid secretion under the following
standardized experimental conditions.
0.1 mM cimetidine (H2 receptor blocker) per chamber added from the
nutrient side.
48
1-10 ~g omeprazole (proton pump inhibitor) added from the secretory
side.
Inhibition of maximum acid secreting potential of histamine stimulated
stomach in the presence of 5 mg dose of sample (applied twice) has been
graded as Low, Moderate, Very good and Excellent category. Blocking of the
reversal Qf acid secretion upon withdraw I of sample from the chamber that still
contain histamine has been graded as Poor, Mild and excellent category.
Anti Helicobacter pylori activity- Disc diffusion sensitivity assay
The. two clinically isolated strains: 80A (avirulant) and 121A (virulant)
were used for the experiment. Strained maintained and cultured under
appropriate growth conditions. Samples were dissolved in methanol. Plates
were kept for appropriate time in incubator under optimal growth conditions.
Inhibition zone diameter measured after confluent growth.
Results
Among the various compounds synthesized, none found vastly superior
to parent 4,5-cis-5-styryl-2-oxo-oxazolidine-4-carboxylic acid, except
compounds 21 and 22. 21 and 22 were all found to be active in reducing
ulcerogenesis and gastric acid secretion in pylorus -ligated rat model at
different dose levels. These appeared to be better compound than the parent
compound and perhaps the compound 21was best among the lot. A
comparative account of'% protection of ulcer index and % inhibition of rr secretion, by compound 21, 22 and 4;5-cis-5-styryl-2-oxo-oxazolidine-4-
carboxylic acid is given, in the table 1.
49
Table 1
Treatment Ulcer Index % protection of % inhibition of U.I.* acid secretion *
Normal saline control (n=5) 14 - -Ulcerogen control (n=5) 161 - -
Compound 21 20 mWke:(n=5) 8 97 80
Compound 21 40 mglkg (n=5) 3 98 50
Cimetidine 40 m!!:lk!!: (n=5) 14 91 43
Normal saline control (n=5) 9 - -Ulceroe:en control (n=5) 87 - -
Compound 22 20 m2fk2 (n=5) 33 62 62
Compound 22 10 mglkg (n=5) 55 37 49
Cimetidine 40 m!!:lk!!: (n=5) 6 93 64
Normal saline control (n=6) 4 - -Ulcero2en control (n=6) 94 - -
Compound 22 40 mglkg(n=6) 5 95 66
Normal saline control (n=5) 19 - -Ulcerogen control (n=5) 120 - -
Parent compound 40 m!!:lk!!: (n=5) 19 84 56
Parent compound 20 mglkg (n=~ 54 55 0
Cimetidine 40 m!!:lk!!: (n=5) 13 89 85
* Data set were compared with their respective 'ulcerogen control' and were expressed as % inhibitions.
In organ chambered frog stomach mucosa model all the above three
compounds were tried both from the nutrient side( as with cimetidine) as well as
secretory side (as with omeprazole). None of these compounds showed any
potential in this experimental model. Formalization of the quantitative analysis
to a qualitative scoring pattern gave the score for both cimetidine and
omeprazole (considered as 100%) as +8. Also none among the three including
4,5-cis-5-styryl-2-oxo-oxazolidine-4-carboxylic acid showed any anti
Helicobacter activity. No significant effecte of these compounds was observed
on nitric oxide synthetase, and wound healing.
50
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