Note: Descriptions are shown in the official language in which they were submitted.
107~89
This invention relates to novel chemical compounds which are useful
as intermediates in the synthesis of 6-(p-hydroxyphenylglycylamido)-penam or
7-~p-hydroxyphenylglycylamido)-cephem compounds.
The novel chemical compounds of the invention have the general
formula:
H o h
( 3 )3 ~ N~ 3 Cl~ l I
wherein Y is I or ~
These novel compounds are prepared by reacting D-~-)-p-trimethyl-
silyloxyphenylglycin-N-carboxyanhydride with a N-hydroxyimide of the general
formula:
O
C
HON / ~ Y II
O
~herein Y has the meaning defined above, in the presence of a hydrochloride
of a weak amine and in an inert solvent.
The reaction is preferably carried out in the presence of pyridine
hydrochloride and in methylene chloride.
The novel compounds thus prepared may be isolated or may be utilized
in situ in a process for the production of 6-(p-hydroxyphenylglycylamido)-
penam or 7-~p-hydroxyphenylglycylamido)-cephem compounds as active esters.
Several activated esters of protonated amino acids have been described in the
20 literature (Tetrahedron Letters 1965, 95, J. Chem. Soc. C 1968, 1219), but
such compounds have only been utilized as amino components in peptide syn-
thesis.
In general, the utilization of proton protection of amino groups in
peptide synthesis has up till now met with at least one major obstacle:
-1- ~
1071~89
Proton migration is unavoidable, thus hampering the formation of the
peptide bond with the unprotonated amino component.
The invention also relates to a process for preparing 6-~p-hydroxy-
phenylglycylamido)-penam or 7-(p-hydroxyphenylglycylamido)-cephem compounds,
said process comprising the steps of reacting a compound of the general for-
mula:
(~3C)35i - O- ~ ~H3 Cl~ ~ I
~hrroin Y is ¦ 2 or ~
with a phosphite amide of an ester of 6-aminopenicillanic acid or of an
- 10 ester of 7-amino-3-cephem-4-carboxylic acid in the presence of the hydro-
chloride of a weak amine.
Phosphite amides of esters of 6-aminopenicillanic acid or of
esters of 7-aminocephalosporanic acid are described in Belgian Patent
Specification No. 809,110.
Since the acylation of said phosphite amides with the above de-
fined activated esters is proton catalyzed, a high proton activity has to be
maintained in the reaction medium throughout the acylation. Such a high
proton activity is preferably provided by using as said hydrochloride pyridine
hydrochloride.
The yields obtained by the process of the invention are high and
racemisation of the sterically labile D-(-)-p-hydroxyphenylglycyl is not
observed.
The invention will now be described in further detail with reference
to the following examples.
EXAMPLE 1
p-Trimethylsilyloxy-D-(-)-phenylglycyloxysucc _ imide, hydrochloride.
0.575 g (5 mmoles) of N-hydroxysuccinimide are added to a solution
.
107~8~
of 0.58 g (5 mmoles) of pyridine hydrochloride and 1.33 g ~5 mmoles) of p-
trimethylsilyloxy-D-(-)-phenylglycine-N-carboxyanhydride in 17 ml of dry
methylene chloride at 0C. Carbon dioxide is evolved, and after 1 hour only
traces of N-carboxyanhydride can be detected by a thin layer chromatography
(silica gel, benzene/acetone 1:1, sprayed with nin-hydrin). The white,
crystalline precipitate formed is isolated by filtration to yield 1.02 g
(55%) of p-trimethylsilyloxy-D-(-)-phenylglycyloxysuccinimide, hydrochloride.
Analysis:
Calculated for C15H21N25SiCl
C: 48.33%, H: 5.68%, N: 7.51%, Cl: 9.51%
Found: C: 48.25%, H: 5.37%, N: 7.54%, Cl: 9.74%
The IR spectrum (KBr) shows characteristic absorption at 1815 cm 1,
1780 cm 1 (ester), 1730 cm 1, 1710 cm 1 (cyclic imide),and 840 cm 1 (tri-
methylsilyl).
The NMR spectrum (D-DMF, Ext.) shows characteristic signals at:
~ ppm Correlation Integral
0.05 (s) Trimethylsilyl 9 H
2.9 (s) 0=C-CH2-CH2-C=0 4 H
5.9 (s) Benzyl-H 1 H
7.05 (d) J=9 Aromatic-H 2 H
7.6 ~d) J=9 Aromatic-H 2 H
8-10 ~broad) NH 3 H
EXAMPLE 2
p-Trimethylsilyloxy-D-(-)-phenylglycyloxyphthalimide, hydrochloride.
2.65 g (10 mmoles) of p-trimethylsilyloxy-D-(-)-phenylglycine-N-
carboxyanhydride and 1.16 g (10 mmoles) of pyridine hydrochloride are suspend-
ed in 200 ml of dry toluene at room temperature. Finely powdered N-hydroxy-
phthalimide (1.67 g, 10 mmoles) is added, and the mixture is stirred for 24
hours. The precipitate is isolated by filtration and washed thoroughly with
methylene chloride to yield 3.66 g (85%) of p-trimethylsilyloxy-D-(-)-
phenylglycyloxyphthalimide, hydrochloride.
-- 3 --
~C~71~89
Analysis:
Calculated for ClgH21N205SiCl:
C: 54.33% H: 5.03%
Found: C: 54.37% H: 4.92%.
The IR spectrum (KBr) shows characteristic absorption at 1820 cm 1
and 1790 cm 1 (ester), 1750 cm 1 ~cyclic imide), and 840 cm 1 (trimethylsilyl).
EXAMPLE 3
p-Hydroxyampicillin
Method A:
4.2 ml (30 mmoles) of triethylamine are added to a suspension of
3.24 g (15 mmoles) of 6-aminopenicillanic acid and the mixture is stirred at
room temperature until a clear solution is formed. 1.89 ml ~15 mmoles) of
trimethylchlorosilane are added dropwise and the mixture stirred for 1 hour,
then cooled to 0C, whereafter 1.35 ml (15 mmoles) of ethylene chlorophosphite
is added during 1/2 hour to produce trimethylsilyl 6-ethylenephosphiteamido-
penicillinate. At this point, 2.9 g (25 mmoles) of pyridine hydrochloride,
2.66 g (10 mmoles) of p-trimethylsilyloxy-D-(-)-phenylglycine-N-carboxy-
anhydride, and 1.15 g (10 mmoles) of N-hydroxysuccinimide are added all at
once and in the order mentioned. The mixture is stirred at 0C overnight,
whereafter enzymatic titration indicates a 96% yield of penicillin.
A solution of 6.7 g of sodium dioctyl sulfosuccinate (Manoxol OT,
BDH) in 50 ml of ethyl acetate are added, and the methylene chloride evaporat-
ed in vacuo. The mixture is poured into ice-water, the pH adjust~d to 2 with
phosphoric acid, and the phases separated. The aqueous phase is extracted
twice with 1.67 g of sodium dioctyl sulfosuccinate in 10 ml of ethyl acetate.
The combined organic extracts are added to 10 ml water, and the pH adjusted
to 4.9 with dicocomethylamine (KEMAMINE T-6501), and stirred 1 hour at 0C
to complete precipitation of the crystalline p-hydroxyampicillin trihydrate.
3.4 g of the product (80%) are isolated by filtration. Enzymatic titration
indicates a purity of 80%, and one reprecipitation from water at iso-electric
pH produces the pure compound, showing IR and NMR spectra identical with
Trade Mark
~ 4 ~
1~:97~39
those of the authentic material.
Method s:
2.4 ml ~30 mmoles) of pyridine followed by 1.9 ml ~15 mmoles) of
trimethylchlorosilane and 1.35 ml ~15 mmoles) of ethylene chlorophosphite are
added to a suspension of 3.24 g ~15 mmoles) of 6-aminopenicillanic acid in
23 ml of dry methylene chloride. An exothermic reaction starts, bringing the
mixture to a mild reflux. After 2 hours stirring at room temperature a small
sample is evaporated, dissolved in deuteriochloroform, and the NMR spectrum
recorded: ~External standard: TMS). The 6-hydrogen is represented by a
multiplet of four signals, centered at ~ = 5 ppm, from which by first order
analysis the following coupling constants may be deduced:
JPNCH JHccH: 4 5 Hz
Addition Gf excess of triethylamine to the NMR tube converts this
spectrum to the known pattern of the free base.
The reaction mixture is cooled to 0C, 2.66 g ~10 mmoles) of p-tri-
methylsilyloxy-D-~ phenylglycine-N-carboxyanhydride, and 1.15 g ~10 mmoles)
of N-hydroxysuccinimide are added, and the mixture stirred at 0C overnight.
Enzymatic titration indicates a yield of 98%. The product is precipitated by
addition of 1.6 ml of pyridine and 7 g of activated carbon ~NORIT SU 18,
containing 7.5% of water). After being stirred for 1 hour at 0C and 1 hour
at room temperature, the precipitate is isolated by filtration and resuspended
in 50 ml of ice-water. The carbon is removed by filtration ~enzymatic titra-
tion at this point indicates 75% yield), 4 g sodium perchlorate are added,
pH is adjusted to 1.5 with perchloric acid, and the product extracted with
n-butanol as the perchlorate salt. To the combined butanol extracts 50 ml
water are added, pH is adjusted to 7 with triethylamine, and the product ex-
tracted back into water. The combined aqueous phases are adjusted to pH 4.8,
and dissolved butanol removed b~ azeotropic distillation in vacuo, whereby
the p-hydroxyampicillin crystallizes as the trihydrate. The first crop of
crystals amounts to 1.66 g ~39%) showing IR and NMR spectra identical with
those of authentic material. A further crop of crystals may be obtained from
the filtrate.
-- 5 --
1071189
EXAMPLE 4
p-Hydroxyampicillin.
A suspension of 1.08 g (5 mmoles) of 6-aminopenicillanic acid in
12.5 ml of dry methylene chloride and 1.4 ml (10 mmoles) of triethylamine is
stirred at room temperature until a clear solution is obtained. The mixture
is then cooled to -40C, and 0.45 ml (5 mmoles) of ethylene chlorophosphite
are added. The mixture is brought to room temperature and stirred for one
hour. 0.3 ml (2.5 mmoles) of dimethyldichlorosilane is added and the mixture
stirred overnight at 0C. 0.4 ml of pyridine and 1.86 g (5 mmoles) of p-
trimethylsilyloxy-D-(-)-phenylglycyloxysuccinimide, prepared as described in
Example 1, are added to said solution.
The reaction is followed by enzymatic titration of penicillin
yield:
Time Yield
1 1/2 h 50%
2 1/2 h 63%
3 1/2 h 70%
20 h 70%
The penicillin produced behaved identically with authentic p-
2Q hydroxyampicillin in high voltage electrophoresis at pH 7. The product may
be isolated as described in Example 3.
EXAMPLE 5
7-(D-~-amino-~-(p-hydroxyphenyl)-acetamido)-3-(1,2,3-triazol-
- 5-ylthiomethyl)-3-cephem-4-carboxylic acid.
1.56 g (5 mmoles) of 7-amino-3-(1,2,3-triazole-5-yl-thiomethyl)-
3-cephem-4-carboxylic acid are suspended in 20 ml of dry acetonitrile, 2.1 ml
(15 mmoles) of triethylamine are added, and the mixture is stirred for about
2-3 hours at ambient temperature until a clear solution is obtained. The
solution is cooled to 0C, and 0.45 ml (5 mmoles) of ethylenechlorophosphite,
3Q dissolved in 2.5 ml of acetonitrile, is added. The mixture is stirred for
30 minutes, brought to room temperature, and 1.26 ml of trimethyl chlorosilane
(10 mmoles) is added. After stirring for 2 hours, the precipitated triethyl-
-- 6 --
1~7~189
amine hydrochloride is removed by filtration (1.43 g). 2.32 g (20 mmoles)
of pyridine hydrochloride, 2.0 g (7.5 mmoles) of p-trimethylsilyloxy-D-(-)-
phenylglycine-N-carboxyanhydride and 0.86 g (7.5 mmoles) of N-hydroxysuccin-
imide are added to the solution of bis-trimethylsilyl-7-ethylenephosphite-
amido-3-~1,2,3-triazol-5-yl-thiomethyl)-3-cephem-4-carboxylate, and the mix-
ture is stirred at 0C overnight. High voltage paper electrophoresis indi-
cates a nearly quantitative acylation.
For recovering of the reaction product, sodium dioctylsulfosuccinate
(10 mmoles) are added, the solvent evaporated in vacuo and replaced by 30 ml
of ethyl acetate followed by 15 ml of ice-water. The pH is adjusted to 1 and
the mixture is stirred for 15 minutes and filtered,followed by separation of
the phases. The aqueous phase is extracted tw~cewith 5 ml of ethyl acetate
containing sodium dioctylsulfosuccinate ~2.5 mmoles).
The transfer of the product to the organic phase is confirmed by
paper electrophoresis. The combined organic extracts are treated with 1 g
of active carbon ~Norit SU 18) and filtered through filter aid. Methanol
~9.5 ml) and water ~0.5 ml) are added, and pH is adjusted to 4.5 with tri-
caprylamine. A white precipitate is formed, and after stirring for 1.5 hour
at 0 C the product is isolated by filtration, washed with ethyl acetate and
methanol and dried in vacuo to yield 1.4 g of a white powder, showing a single
spot on high voltage paper electrophoresis, moving as an anion at pH = 8, and
as a cation at pH = 5. The MMR spectrum shows signals corresponding to the
proposed structure.
