Note: Descriptions are shown in the official language in which they were submitted.
3~
Background of the Inven-tion
l. Introduction
This invention reIates to derlvatives of cephalosporins
and more particularly to 7-carbon and 7-oxy~en analogs of 7-
aminocephalosporanic acid and bioloyically active derivatives
thereof.
2. Descrip-tion of the Prior Art
Follow~ng the discovery of the penicillins and their
synthesis, perhaps one of the most lmportant advances in medical
research was the dlscovery of the cephalosporin antlbiotics and
their use in cllnical medicine. The cephalosporin antibiotics,
though not penicillins, have a structure quite similar to
penicillins and the two can be co-produced in the fermentation of
a cephalosporium organism
Additionally, the simllarity between cephalosporins and
penicillins has suggested that interconversions between the two
series of antibiotics are feaslble. 9uch conversions are des-
crlbed by R.B. Morin et al, "Chemlstry of Cephalosporin Antibiotics
XV. Transformation of Penicillin Sulfoxide", J. Amer. Chem. Soc.
91, 1401 (1969). An illustrative transformation between the two
antlbiotic families is the heating of Penicillin V sulfoxide ~;
methyl ester with a trace of acid to afford a desacetoxy
cephalosporin.
Because of such similarity in both structure and chemical ~ -
reactivity, considerable research has been devoted to the
derivatization of cephalosporins, employing chemical reactions
analogous to those finding util;ty in penicillin modification.
For
~ 2-
~L~(3Z3~
example, 7-aminocQphalosporanic acid ~7-ACA) may be ob-tained
by mild acid h~drolysis of Cephalosporin C. This acid may -then
be readily transformed into myriad derivatives of varied chemical
properties and biological activity. For example, acylation of
7-ACA wlth phenylacetylchloride af~ords an ester having an anti~
bacterial activity about 100 times that of Cephalosporin C.
Numerous other reactions of 7-ACA are likewise well-known and
reported in the literature. Thus, acyl groups, isocyanates
isothiocyanates, halogen compounds, methylisoureas, e-thylene ~ - -
oxides, ethylene imines and -the like have been introduced into
7-ACA.
In addi-~lon to the above derivatives, reactions modifying
both the ~ lactam and the dihydrothlazine ring system~ of cephalo-
sporins are well-known. For example, epimerization at C-7 may be
effected with tr1ethylamine in refluxing chloroform. Analogously,
reactivity through the C-3 substituen~s~ the carboxyl group and
the C3 4 double bond affords a vast number of possible derivatives.
Reactions of the cephalosporlns, as illustrated above,
are reported in part by R.B. Morin and B.G. Jackson, "Chemistry
of Cephalosporin Antibiotics", Progress in the Chemistry of
Organic Natural Products XXVIII, Wein, Springer-Verlag (1970).
A new series of derivatives o cephalosporins has récently
been described in our co-pending Canadian Application No.
232,812, filed August 5, 1975. This series was based upon
the discovery of certain esters of 7~oxocephalosporanic acid
and methods for their formation. These esters were e~ployed as
intermediates in the formation of the biologically active oxygen
analog (7~-hydroxycephalosporanic acid) of 7-ACA. Such an analog
serves as the starting material for a wide variety o biologically
--3--
. . .
3~13
active derivatives analoyous to the derivatives of 7-ACA,
described abo~e.
For brevity, the commonly accep-ted abbrevlations of
"7-ACA" for 7-amlnocephalosporan:ic acid and "6-APA" for 6-amino-
penicillanic acld will be used -throughout this specification.
Summary of the Invention
The present invention provides a new syn-thetlc route
to the 7-oxygen analogs of 7 ACA~ described in co--pending
Canadian Application No. 232,812. Further, said synthetic
scheme affords access to a novel class of derivatives of 7-ACA,
the 7-carbon analogs thereo. More generally, the synthetic
scheme, disclosed herein, permlts the synthesis of a wide variety
of new derivatives o the cephalosporins. These carbon and
oxygen anlo~s of 7-ACA are analogous to and prepared from the
carbon and oxygen analogs of 6-APA, disclosed ln Canadian Patent
No. 1, 061,332, issued August 28, 1979.
The synthetic approach to these two cephalosporin ~ -; -
series involves the oxidation of 6-carbon or 6-oxygen analogs
of 6-APA and the rearrangement of the resulting sulfoxide to
the respective carbon or oxygen analog of 7-ACA. Such a method
provides a convenient and facile method of introducing side
chains into the cephalosporin skeleton and is useful for the
formation of new classes of biologically active cephalosporins.
/~,~, _ ~,_
23~
Description of the Preferred Embodiments
As noted above, the syn-thesis of the 6-carbon and 6- ;
oxyyen analoys of 6-APA is described ln Canadian Patent No.
1,061,332. The ~erman paten-t application corresponding to
Canadian Patent 1,061,332 is German Application No. P 24 16 492.9, , ~-
which was laid open October 31, 1974. That scheme requires the
esterification of 6-AP~ with a pharmaceutically acceptable
blocking qroup to protect the free acid substituent. This ester
of 6-APA is subsequently transformed into an ester of 6-oxo -
penicillanic acid through deamination and oxidation of the
resulting hydroxy compound wi-th diisopropyl carbodiimide and
dimethyl sulfoxide. ~
;
~ a
~ ~23~
Esters of 6-oxo-penicillanic acid may be transformed to
a carbon analog of 6-APA through Wittig reaction with a suitable
phosphorane, saturation of the resulting exo-cyclic double
bond and rem~val of the protective group~ Oxygen analogs are
produced throu~h reduction of the 6-oxo group and protective
yroup removal. soth of these analo~ classes are of course modi-
fiable by appropriate substitution to a wide variety of derivatives
both biologically active and inactive. These analo~s in accordance
with this invention also serve as starting materials for the ~.
formation of -the correspond;ng carbon and oxygen analogs of 7-ACA.
Oxygen analoas of 7-ACA are produced through a scheme
requiring initial protection of the free acid of an oxygen analog :
of 6-APA with an appropriate pharmaceutically useful or readily
removable protective group. Such a process is disclosed by Y.S.
~o and J.C. Sheehan, J. Amer. Chem. Soc. 94, 8253 (1972). The
general formula of such an es-er ls set forth below:
X H
R' - O
I~ O /~ ~iCO~R
wherein P~ represents the protective group. Groups employed in this
manner include hydrogen or substituted or unsubstituted (1)
aliphatic, alicyclic or aromatic, e.g. alkyl, preferably lower
alkyl such as methyl, ethyl or propyl, alkenyl, pre~erably lower
alkenyl, such as ethenyl, propenyl and butenyl; aryl; alkaryl;
- alkinyl, preferably lower alkinyl such as ethinyl, propinyl and
butinyl; cycloalkyl or cycloalkenyl, such as cyclohexyl; aralkyl
such as benzyl and phenylethyl; and ~ trichloroethyl; (2)
~ -5-
~ ~236~3
.
acyl compounds~ including acylalkyl~ preferably lower acylalkyl ..
such as acetylmethyl~ acetylethyl, acetylpropyl; acylamino,
preferably lower acylamino, such as acetylamino, propionylamino, -:
and butyrylaminoi acylaminoalkyl, preferably lower acylaminoa-lkyl,
such as acetylaminomethyl, acetylaminoethyl, imino (see U.S.
Patent No. 3,876,630 issued April 8, 1975 to Ishimara et al)~ and
arylacyls such as phenylacyl and its derivatives ~e.g. p-methoxy-
phenacyl, m-chlorophenacylj and-2,5-dimethoxyphenacyl~;-- (3) salt
.- formers,_e.g.. -alkali-metal-:ions such as-sodium or potassium ions,
or organic groups such as tri~alkyl)ammonium ~preerably---tritlower
alkyl) ammonium, eOg. triethylammonium) or piperidlno or N-alkyl
~preferably lower alkyl)piperidlno, e.g. N-ethylpiperidino, or
benzylammonium or dicyclohexylamino, and :(4) organo silyl-groups
such as trimethyl silyl, preferably trl(lower alkyl)sïlyls.~- :-
While i* should be understood that some of the aforesaid groùps
: may be more difficult to rem~ve ~
~ Z3~38 -.
than others, most are groups heretofore used as protectlve groups
in analogous reactions of penicillins and cephalosporins~
Removal of such blocking groups is effected pursuant to recoy-
nized and well-known procedures, dependent upon the identity of '
t'he protective group.
R' represents an organic electrophillic moiety. A
wide variety of substituents are suitable, including substituted
or-unsubstituted aliphatic, e.g.~ alkyl, preferably lower alkyl,
such-as~methy~ -ethyl-,=propy-l-,_~exyl,~ etc.-; ali-cyc-lic~ e.g.-cyclo-
alkyl', such as-cyclopentyl, cyclohexyl, methylcyclohexyl;
aromatic, e.g~ phenyl,benzyl, tolyl; acyl, e.g. benzoyl, pheno-
oxyacetyl, chloroacetyL and bromoacetyl ~carboxylio carbonic;
sulfonic; and amide radicals. Preferably R' may be selected
from the group of (1) organic acyl radicals such as phenyl-
ace~tyl, phenoxyacetyl, 2,6-dimethylb'enzoyl, a-carboxyphenylacetyl,
and -aminophenylacetyl; (2) organic carbonic acid radicals such
as carbethoxy,-carbobenzyloxy, and ~ ,-trichlorocarbethoxy;
(3) organic sulfonic acid radicals suCh as methylsulfonyl;and
(4) amide radicals such as carbamyl, phenylcarbamyl, and methyl
20---- car~amy~ Most=p~eferred---~re--tho-se R ! -~--groups--which--are-bound
to the oxygen by a carbonyl group. Suitable R' substituents
include hydrogen, fprmyl, acetyl, phenyl, phenylacetyl, phenoxy- ~O
acetyl, p-aminophenylacetyl, ~-carboxylphenylacetyl, benzyl,
benzoyl, 2-thienylacetyl, aminocarbamyl, phenylglycyl, methyl
sulfonyl, benzyl sulfonyl, o-aminophenylsulfonyl, p-aminobenzyl-
sulfonyl, carbobenzoxy, ~carbonaphthoxy, carbo~2-thienylmethoxy),
and (l-p'henyl 2-formylamino)ethoxycarbonyl.
~ 23~3
X represents hydrogen or an organic nucleophile
Substituents employed in this manner include inter ali~a cyano,
alkoxy, aryloxy, alkylamino, arylamino, halogen, hydroxyl, carbo-
alkoxyl, axyloxy, carboxyl, carbonyl, sulfonyl, carbamyl, thio- .
carboxyl, and analogous functionalities.
The corresponding oxygen analog of 7-ACA is formed .-
by oxidation of an ester of an oxygen analog of 6-APA (I~ above. .
: Such sulfur oxidation-can-be accomplished by myriad.techniques
well known in the-art.-~--Oxidizing agents--such as m-chloro-~
10 - perbenzoic acid, ozonej and-~sodium metaperioda-te are-represen-..
tative among numerous such reagents.
The oxidative scheme is preferably~carried out in
organic solvents such as chloroform or methylene chloride at
0 C. For example,-a solution of;-oxidiz-ing agent--such-as
m-chloroperbenzoic acld-~in said~solvent.may.-be added-dropwise
to a solution of said ester and~the`;~xidation allowed:to prooeed
to completion. .~
(~ 23~ ~
' '' . - " " ~
Th~ sulfoxide Or an ester of an oxygen analog of 6-APA
. II) may be transformed by re-arrangement into the correspondlng
ster Or an oxygen analog of ~ACA (III) This re-arrangernent is
referabl.y carried out by heating the sulfoxide ~II? wit~ a.trace .
of acid or acid producing reaotants. Reactants'useful for this
purpose comprise for example-derivatives of sulfonic acid or an-
hydrides such as methane sulfonic acid or p~toluene sulfonic
acid and organio carboxylic acids or anhydrides suoh~as acetic
acid or acetic anhydride. .~ - :
Such heating is.prefera~.ly carried out-at 80-lbo c in
. solvents.wherein'the water produced as-a by-product to the trans~
formation can be a~eotropically distilled from the reaction mixtur
to .ald in effecting complete converslon. Such solvents include
without.-limitatlon acetic anhydrlde, benzene, xylene, dimethyl
5 aoetamide (DMA~ or toluene.
The desire'd transformation, having be.en effected,:the
blocking group may be readily removed thereby adducing the.free '
-acid----(--IY)'-by--such-procedures.as hydrogenation or'hydrolysis with
. trifluoroacetic ac~d (TFA) or by employing other methods well-knowr :;
20 in the art.
A reaction sequence for forming the oxygen analog of 7-ACA ....
from 6-ApA for illustrative--purposes only is as follows'.
~ r
I ~,
¦ m~CI C6H4C3H
I I
I I ~CH3SO3 H
~ ~:
~ ~ o~
C2 R
I U
( 2 H
The fr~e acid (IV) is an oxygen analog of 7-ACA. It is
bioloyically active. Both -the free ac~d (IV) and the ester (III)
can serve as starting materials or the formation of many other
biologically active derivatives of the oxygen analogs of 7-ACA.
Many of these deriva-tives are disclosed in co-pending Canadian
Application No. 232,812. In such functionalization well~known
side chaln modification, ~-lactam and dihydrothiazone ring
modifications and varied substitutions produce myriad derivatives
of this cephalosporin series. Exemplification of these various
conversions and modifications, analogous to those employed in
cephalosporins themselves, are disclosed in Webber et al, J.
Amer. Chem. Soc~, 91, 5674 (1969); Naylor, Proc. R. Soc. Lond B
179, 357 (1971); and R.B. Morin and B.~. Jackson, "Chemistry
of Cephalosporin Antibiotics", Progress in the Chemistry of
Organic Natural Products XXVIII, Weln, Springer-Verlag (1970).
Carbon analogs of 7-ACA are produced by analogous
methodology. Thus, initial protection of the free acid of a carbon
analog of 6-APA with an appropriate pharmaceutically use~ul
or readily removable group must be effected. Such blocking
is analogous to that described for the oxygen analogs of 6-APA
described above. The general formula of such an ester is set
forth below:
Y r N~
C2 R
wherein R, R' and X are as described above.
_ g _
, ~ Z3~3~ ~
~' I , _. . , ,
¦ The c~nver810n of thls ester ~V) to ~ carbon analog o~
. ¦ 7-AC~ analogou~ *o that de~cribed aOove for the conver~iOn of
¦ an ester. o~. 6-~PA to an oxygen analog of 7-ACA. I'hat 1~, a ~chem
¦ for illustratlrl purposefi only as follows: .
9 1 ¦ y /~
¦ O ~ ~2 R - ~ ,,
lQ . ¦ . l rnCl - C6 H4~03-H . ~ .
, I ' X .il ' '~I' -~'
Y I R ~
..... _. I : ¦ CH3s03~ : .
: ~ DMA / ~H "................. - .;
. X _ S
2D ~ II R L~ l
. ,~" N ~-
C2R
.
. ~ r
X H . .
~ ¦ ~:I R /~
.. o~ N
C02~
' - 10 -
The free acid (VIII) is a carbon analog of 7~ACA. It
is biolo~ically active. soth the free acid (VIII) and the ester
(VII) can serve as starting rnaterials for -the formation of many
other biologically actlve derivatives of the carbon analogs of
7-ACA. In this functionalization~ well-known side chain modifi-
ca-tions and ~,lactam and dihydrothiazine ring modificakions and
substitutions afford myriad derivatives of this novel cephalo-
sporin series. Illustrative of these conversions are the well-
known reactions of cephalosporins disclosed in Webber et al,
Naylor, and Morin and Jackson cited.
Through the utilization of appropriate starting materials
and/or the interconversions described above, a wide variety of
carbon analogs of 7-ACA can be adduced. Such a series is
represented by the general formula-
X H S
R' y ~ R"
O
~2 0 C0 2 R
wherein R and R' are as described above, and R" is an organic
nucleophile, preferably hydrogen or acyl oxy, e.g. formyl oxy,
aceto, phenylacetoxy, benzoyloxy, but a wide variety of substi- ~ '~
tuents can be placed there (e,g. halogen, hydroxyl, alkoxyl, :
:
aryloxyl~ alkylamino, arylamino, carboxyl, carbonyl, sulfonyl,
carbamyl, thio carboxyl, and other analogous functionalities).
'
~! -11- ..
- ,
~ 3~
.. . ..
Speclfic examples of R ' and R" are set forth below:
. ' O ' ;: ' " - ~
. 1 -- , ,.
' -C CH2 C6H5 ,
.. 2 6 5
O ' ' :~' ' ' ' ' ,' ' "'' ,
-C - CH - C 6H5. ~
O NH2 ' ' , , ~ .
- C - CH - C6H5 . : . .
0 COOH
-C~(
6 ,~
.. _ C - Gfl2 ~N ~
- C - CHz~9 .
- C - CH ~ '~1,
,C, H "C, CH3
- ~ NH2, ~~ -~H C6H5
'0 3 '' 3
-C - O CH2 C6H5
- 12 -
~ Z~8
R~l
- H, -Cl, -Br, -OH, ~OCH3 .
._ -OCH2CH3~ -OC6H5
- o~~CH3
. . ~ - .
. -N ~ .
. H
. -O - C - NH . .
O ~' '' ' ' ', ,~
-OC - NCH3--
. O ', ' , , ',
-S - C - CH3 . ~ - :
O ' , ' ~ .~
~ 5 - ~ 6D5
-3 -C -NH~
. ~
The inventlon will be better understood b~ reference to
the following e~amples.
, . ,
- ~3 - .
ll(3za~s
¦ Benz 1 6~-h drox -6~- c ano enicillanate
I _ Y Y Y Y P .
I Liquid hydrogen cyanide (Vogel Method? was transferred
¦to a flask containing benzyl 6-oxo-penicillanate (2.04g~ and a
¦few crystals of sodium cyanide. Rapid solid formation was observe
¦durin~ this addition. The mixture was allowed to stand at 0 for
3 min. and subsequently, at room temperature to evaporate the
¦excess hydrogen cyanide. ;Any residual hydrogen'cyanide was remove
¦at reduced pressure. The solid was collected by filtration and
¦washed wit,h benzene to afford l.lOg product (54Z from the crude
¦starting material?. After-recrystal~ization=-from methylene chlori e,
¦the'white, shiny crystalline benzy~ -6~-hydroxy-6a-cyanopeni-eillana e--
¦was obtained, mp 148-162 (decomp). [a]25D;=~188 (C=0.545,'CHCl3)
: ¦IR ( KBr, C-1~ 330o, 1790, 1730; nmr (DCCl3g~ppm3: 7.50 ~s,5H);
¦5.90(S~1H); 5.35 (s,2H), 4~70(s,1H~, 3.~0~s,1H), 1.63(s,3H~
¦1.50(s,3H). ~ ~' `
Anal. for C~6Hl604N2S (332.4l) -~
¦Calc.: C, .58.00; H, 4.83, N,8.48, S, 9.64 - ' '
Found: C~ 58.09, H, 4.79~ N,8.479 S, 9.59 -
- Benzyl-6~-h~droxy-6a-cyano-penicillanate-1-sul~oxide
. ~ .
To a cold well-stirred solution' of benzyl 6a-cyano-6~
hydroxypenicillanate (528.5 mg9 1.59 m mole) in 30-ml--of methylene
chloride and 5 ml of tetrahydrofuran was added 274.4mg (1.59 m mol )
of m-chloroperbenzoic acid in 10 ml of methylene chloride over a
15-minute period. Stirring at ice-bath temperature was continued
for one hour followed by gradual warming to room temper~ture. The
reaction mixture was washed with three 20-ml portions of phosphate
buffer (pH 7.5), two 20-ml portions of water and then dried
over MgS04. Removal of solvent in vacuo afforded 610 mg of crude
¦¦sulfoxide lch waq recrystalllzed from chloroform-hexane to glve ¦
' 1~
-14-
`" 1~
401 mg (72.6%) of pure sulfoxide, mp 120-122; lr (KBr,Cm ): 3260,
1790, 1740, nmr (CDC13,ppm): 1.14 (s,3H), 1.82 (s,3N),
4.78 (s~lH)~ 5.19 (s, lH), 5.28 (d,2H)~ 7.4 (s,5H). - ';'
. , ~ , ~,
Ana~ for C16H16N25S(348)
Calc.: C, 55.16; H, 4.63; N, 8.14; S, 9.21 '
Found:' C, 55.15; H, 4;61; N, 7.96; S~ 9.Z6
' Benzyl-6a-Cyano-6B-phenoxyacetoxypenicillanate~ Sulfoxide
A cold (lc-e bath)-solution--of 348-mg ~ m mole)-o~ benzyl-
6a-cyano-6~-hydroxypenicil-lanate-1-sulfoxide in 75 ml-of methyIene
chloride was-treated with phenoxyacetyl chloride (275.4 mg, 1.61
m moles) and 0.14 ml of'triethylamine (101 mg, 1 m mole). The '
reaction mixture was stirred at ice-bath temperature ~ror z~s hours
Washing~wi~h two 25 ml portions of~-water, two 25-ml portions~of
5% sodium bicarbonate, one 50-ml~portion of water, drying~o~er
magnesium sulfàte and removlng~solvent ln vacuo'afforded 0.507g
of a light yellow oil; ir (ne~at, Cm~i~~1810, 1775,'1750; nmr~
(CDC13;ppm) 1.04 (s,3H), 1.56 (s,3H), 4.67 (s,2Hj, 4.80'(s,1H)~
5.34--(s,2H), 5.29:(s,1H)3 6.75~1'.8~8~(m,1~0H').~~ The~~phenoxyacetylate
product was suitable for the sulfoxide rearrangement without
further purification However~ purification if desired is effected
by column'chromatography on silicic-~acid using methylene chloride:
ether, (9:1) as eluent.
.
Benzyl 7-Cyano-7~-phenoxyacetoxy-3-desacetoxy-cephalo-
sporanate
, : '
A ~olution of 633.2 mg (1.31 m moles) of benzyl 6a-cyano-
6~-phenoxyacetoxypenicillanate-1-sulfoxide in 12 ml of dry
benzene and 9 ml of N,N-dimethyl-acetamide containing three drops
~323~
of me-thaneslllfonic acid was h~ated at reflux (Dean-Stark trap)
for 12 hours. The solvent was then removed in vacuo to afford
0.8143 g of a dark red oil. Thls oll was adsorbed onto a 52 x 2.8
crn column containing 75 g ~ silicic acid. The column was eluted
with methylene chloride: ether, 9.5:0.5. Such chromatographic
fractiona-tion aforded 0.427 g of a yellow semi-solid. Approximate-
ly 1.34 mg of this rnaterial was placed onto two prepara-tive
chromatography plates (20 x 20 cm x 2 mm silica ~el 60F-254).
Elution wi~h benzene: ethylacetate, 4:1, afforded 90.2 mg of the
rearranged product as the fraction o highest rf, ir (CHCl,Cm 1)
1780, 1715; nmr (CDC13,ppm) 2.28 (s,3H), 3.0S-3.19 (d,2H), 4.94
(s,2H), 5.30 (s,2H), 5.34 (s,lH), 6.82-7.61 (m,lOH)~
~ -Trichloroethyl-6~-Carbobenzyloxymethyl-
penicillanate
richlorethyl-6~-carbobenzyloxymethylpenicillanate
was prepared in accordance with the procedures of Canadian
Patent No. 1,061,332. ~t displayed the followlng characteristics:
NMR (CDC13,ppm):1.60 (s,3H), 1.70 (s,3H), 2.8-3.1 (m,2H), 3.8-4.3
(m,lH), 4.50 (s,lH), 4.73 (s,2H), 5.10 (s,2H), 5.57 (d,lH, J=4.5Hz),
721 (s,5H); ir (CHC13Cm ) 1780, 1740 (sh); mp 42-50D;
Anal: Calc. - C, 47.46; H, 4.19; N, 2.91; Cl, 22.12
Found: C, 47.68; H, 4.20; N, 3.09; Cl, 22.25
-Trichloroethyl-6~-Carbobenzyloxymethyl penicillan-
ate-l-sulfoxide
A solution of ~ trichloroethyl-6~-carbobenzyloxymethyl
penicillanate (493.0 mg, 1.02 mmol) in 30 ml of chloroform was
cooled in ice. m-Chloroperbenzoic acid (181.9 mg~ 1.05 m mol)
in 20 ml of chloroform was added dropwise to said chilled
~ -16-
,~,,,7,~,
~ 2~ .
.,
solution over about 30 min. The resulting solution was stirred at
. 05 ror 1 hour and at arnbient temperature for one hour. The'reacti n
mixture was washed'with sodium bicarbonate solutlon anq the organi
layer dried over magnesium sulfate and evacuated to remove the -
solvent. Addition of ether to the residual oil afforded crystalli
zation. Recrystallization of the crude product from methylene
chloride-pet ether yielded the pure sulfoxide as white needles,
mp 153-156; IR(CHC13,Cm 1) 1800, 1780(sh), 1730 and 1185, nmr-
(CDC13,~m)1.37 (s,3H),-1.83 (s,3H), 2.6-4.4 (m,3H), 4~.73 (s,3H),
4;8-5.o (m,3H), 5.I7 (s,3H)', 7.33 (s~5H). ;
~ trichloroethyl-7~-Carbobenzylox~ Meth~1-3-desacetox _
'cephalosporanate
A mixture of the sulfoxides (105.0 mg, 2.09 x 10 mol;
mixture of ~ and ~ isomers), 8 ml of benzene, 6 ml of DMA~and
2 drops of methane_sul~onic acid were refluxed~under a Dean-Stark
trap ~or 17 hours. The benzene was'removed~under~re~ced pressure
and the-DMA by a short path high vac'uum distillatlon (water bath ~ -
50; 2mm~. The residual oil was puri~ied by silica gel chroma-
tograph'(20 x 20 plate, 2 mm) using a ~% methanol-chloroform
eluent. Isolation of the major ~raction afforded the cephalo-
sporanate as-a yellow oil (72.6 mg~-72%). This product~exhibited'
the-fol-lowing properties;
nmr (CDC13,ppm): 2.20 (s,3H), 2.83 (s,lH), 2.91 (s,lH),
3.33 (d,2H; Je4,0 Hz), 3.90-4.40 (m~lH), 4.90 (d,2H: J=3.0 Hz),
5 (d,lH; J=4.5 Hz), 5.33 (s,2H), 6.80-7.50 (m,3H); IR (CHC13,Cm 1
1770, 1730, 1385, 1300. ''
~ 3~ `
.,
7~-Carbobenzyloxy Methyl-3-desacetoxy-cephalosporanic acid
~ , trichloroethyl-7~-carbobenzyloxy-3-desacetoxy
cephalosporanate (75.5 mg, 1.58 x. 10 4 mol) was dissolved in 90%
acetic acid (2 ml). The solution was cooled to 0 via an ice
bath and zinc dust (124.1 mg) was added. The resulting hétero-
geneous mixture was stirred for 3.5 hours. The zinc was removed
by filtration (celite) and washed with methylene chloride (50 ml),
the filtrate being combined wlth an ice water mixture.
The organic layer was separated and washed with ice and
10 - water. The~aqueous phase--was~--extracted-with~methylene chloriae~-(2 x 50 ml). The combined organic fractions were dried over-magne -
sium-sulfate and the solvent removed in vacuo in the absence of
external heating. The last traces of acetic acid were removed
at reduced pressure. I
15 - The residue, an oil, was dissolved in methylene chloride
(20 ml) and extracted with 5% sodium bicarbonate solution (10 ml).
The organic layer-was---separated-and-~;the aqueous-~layer after--coolin ~;
in ice was acidified with 10% hydrochloric acid (10 ml). This
acidi~ied-aqueous--frac~ Qn---w&s--ex-t-rao-ted-w-ith--me-thylene-chloride
(.5 x 10 ml). The combined organic extracts were dried over
magnesium sulfate and the solvent removed in vacuo in the absence
of external heating. -The cephalosporan-ic acid-remained as a clear
oil nmr (CDC13,ppm): 2.23 (s, 3H); 2.93 (d, 2H; J=7.0Hz); 3.33 (d,
2H, J-5.0 Hz); 3.8-4.4 (m7 lH); 4.97 (d, lH~ J=5.0Hz); 5.10 (s, 2H ;
7.27 (s, 5H);8.10 (m, lH).
Bioassay results (minimum inhibitory concentration in
mg/ml): S. Aureaus (200), S fecalis (>400), E Coli (>400)
A. aerogenes (>400), S. pullorum (~4~00), P mirabilis (>400)
P. Vulgaris (>400), S marcescens (>400), K. pneumonia (>400),
and B. Subtilis (>400).
-18-
