Note: Descriptions are shown in the official language in which they were submitted.
- 1 ~;2~
4-16193/-
Diacyl derivativeæ of 4-ftrialkylbenzyl~-p ~rG~Liny
ÇQ~æounds
The present invention relates to novel diacyl
derivatives of rifamycins that carry a substituted 1-
piperazinyl radical in the 3-position, namely 8-O,N- and
8-0,21-0-diacyl derivatives of rifamycin S compounds of
the formula
~H3 ~H3 ~H3
C~3C00~
I ~H ~R3
CH3
Rl R ~-R2 (I~
~ ~?
in which ~ represents lower alkyl, R1 represents tri-
lower aIkylmethylcarbonyl, and one of the radicals R2 and
R3 represents tri-lower alkylmethylcarbonyl and the other
represents hydrogen, to their salts, and to mixtures of
isomeric compounds of the formula I or their salts.
The invention relates also to a process for the
~k
672~l
2 --
manufacture of compounds of the formula I and their
salts, to pharmaceutical preparations containing them,
and to the use of these compounds and preparations.
The numbering used herein corresponds to the
numbering used, for example, in US Patent No. 4 005 077.
Lower alkyl R contains preferably up to and includ-
ing 4 carbon atoms and is, for example, ethyl, propyl,
i-propyl, n-butyl, isobutyl or tert.-butyl, but especial-
ly methyl.
Lower alkyl radicals in a tri-lower alkylmethyl-
carbonyl radical normally contain up to and including 4,
preferably up to and including 2, carbon atoms and
especially one carbon atom, and are, inter alia,
n-propyl, isopropyl, n-butyl or tert.-butyl, especially
ethyl and more especially methyl.
In the compounds O:e the formula I, the radicals R
and R2 or R3 pre~erably have identical meanings.
Non-acylated rifamycin S compounds that have, in the
3-position, a piperazino group substituted in the 4-
position are known. For example, US Patent 4 005 077,
especially Example 77, mentions rifamycin derivatives
that contain, in the 4-position, a benzyl radical that
may be substituted in the aromatic moiety by one or more
alkyl radicals having from 1 to 6 carbon atoms, such as
3-~4-benzyl-1-piperazinyl)-rifamycin SV, 3-~4-(4-methyl-
benzyl)-l-piperazinyl]-rifamycin SV, 3- E 4-(2-methyl-
benzyl)-l-piperazinyl~-rifamycin SV, 3-[4-(3-methyl-
benzyl)-1-piperazinyl]-rifamycin SV, 3-[4-(4-isopropyl-
benzyl)-1-piperazinyl]-rifamycin SV, 3-[4-~2,3-dimethyl-
benzyl)-l-piperazinyl]-rifamycin SV and 3-[4-~4-tert.-
butylbenzyl)-l-piperazinyl~-rifamycin SV. Further
compounds of that type that have, especially, a 4-(2,6-
dimethyl-4-alkylbenzyl)-piperazine radical are describ-
ed, for example, in the PCT application having the
publication no. W0 87/02361. Those compounds are
distinguished by an antibiotic action, especially an
~LZ~6~
-- 3 --
antitubercular action, which can be demonstrated i vivo
in mice and rats and which, as regards the spectrum of
action, corresponds approximately to that of the known
antitubercular agent, rifampicin.
In contrast, the diacyl compounds of the present
invention have, if at all, only a marginal antibiotic
action. Surprisingly, however, they have a lipid-
reducing action which can be demonstrated in animal
experiments, preferably on mammals, for example rats.
For example, it is possible to demonstrate the reduction
of "very low density", "low density" and "high density"
lipoproteins (VLDL, LDL and HDL) in serum in two test
procedures, namely in genetically hypercholesterolaemic
male rats (procedure A) and normolipaemic rats of both
sexes (procedure B).
Albino rats having a hody weight o~ from 180 to
240 g and having free access to normal rat food and
drinking water are used, Sprague Dawley derivatives of
the strain Tif:RAI in procedure A and animals of the
Wistar strain IVa-WI in procedure B. The test compound
is administered orally in a polyethylene glycol solution
(average molecular weight 400~ to groups of from 8 to 10
rats, in procedure A once daily at 8 a.m. for three
consecutive days and twice, at 8 a.m. and 4 p.m., on the
fourth day, and in the case of procedure B, daily for 5
consecutive days. In experiment A the animals are
sacrificed 16 hours, and in experiment B two hours,
after the final administration by bleeding from the neck
under anaesthesia with ether. The animals are given no
food during the 16 hours before they are sacrifice*. A
0.05% aqueous ethylenediaminetetraac~tic acid solution
and a 0.01% aqueous thiomersal solution are added to the
combined serum of from 2 to 3 rats. The serum lipo-
proteins are separated using an ultracentrifuge by means
of 24~hour centrifugation at 78,000 g, 78,000 g and
109,000 g in salt solutions having densities of 1.006,
,
i~Z~672~
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1.040 and 1.21, respectively, and are analysed enzymat-
ically for their content of cholesterol and triglycerides
using the test systems supplied, for example, by Milss
(Lausanne, Switzerland) and B'ohringer (Mannheim, Federal
Republic of Germany).
The antibiotic action is ascertained, for example,
on the one hand in vitro by determining the mean effect-
ive concentration EC50 for the inhibition of the RNA
polymerase of Escherichia coli and by determining the
minimum inhibitory concentration MIC in a conventional
plate test, and on the other hand in vivo, using infected
mice and rats, by determining the ED50 (effective dose
that ensures the survival of 50~ of the experimental
animals). There are used as micro-organisms for the
present purpose especially Mycobacterium tuberculosis TB
H37Rv and Staphylococcus aureus. In the case of com-
pounds having a lipid-reducing indication, an antibiotic
activity is regarded as disadvantageous since it can
result in the formation of strains of micro-organisms
that are resistant to antibiotics, especially when the
compounds are administered over a prolonged period.
; In the test methods described above, the compounds
according to the invention have a significant hypo-
lipidaemic activity both in the case of a single ad-
ministration and in the case of repeated administration
in a dosage range of from approximately 3 to approximate-
ly 50 mg/kg/day; in the above-mentioned tests they are,
however, free of any appreciable antibiotic activity.
It can be demonstrated, for example, that, depending
on the test arrangement, the minimum effective dose of
8-O,N-dipivaloyl-3-~4-(2,4,6-trimethylbenzyl)-1-piper-
azinyl]-rifamycin S when administered once is from
; approximately 3 to approximately 10 mg/kg, and a 50-70%
reduction in the "LDL fraction" can be achieved by the
repeated administration of 30 mg/kg daily. The compound
exhibits practically no antibiotic activity; an EC50 for
.~
~2~672~
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the inhibition of the RNA polymerase is not achieved even
with 100 ~g/ml and the MIC for various pathogenic strains
of Staphvlococcus aureus is approximately 64 ~g/ml. Such
values are approximately 1000 times higher than con-
centrations that are normally necessary for a correspond-
ing effect. The compound also proves to be antibiotical-
ly inactive in vivo at a single dose of 200 mg/kg using
mice infected with Staphylococcu~ aureus. Analogous
results are also obtained with the corresponding
8-0,21-0-dipivaloyl compound.
Especially owing to their LDL-reducing action, the
compounds according to the invention can be used, for
example, as hypolipidaemics for the treatment of hyper-
lipidaemias, chiefly of the types IIa and IIb, and ~or
the treatment o~ arteriosclerosis when the presence oP
hyperlipoproteinaemia constitutes a risk factor.
The present invention relates preferably to com-
pounds of the formula I in which R represents lower
alkyl, especially methyl, and in which R1 and R2 repre-
sent tri-lower alkylmethylcarbonyl in which lower alkyl
contains up to and including 2 carbon atoms, and R3
represents hydrogen, or in which Rl and R3 represent tri-
lower alkylmethylcarbonyl in which lower alkyl contains
up to and including 2 carbon atoms, and R2 represents
hydrogen, and to salts, especially pharmaceutically
acceptable salts, thereof, these compounds being in the
form of mixtures or preferably in the form of one isomer
virtually free of the other isomer, especially in the
form of the corresponding 8-O,N-diacylated compound.
The invention relates especially to the compounds of
the formula I in which R is methyl, and Rl and R2
represent pivaloyl and R3 represents hydrogen, or R1 and
R3 represent pivaloyl and R2 represents hydrogen, and to
salts, especially pharmaceutically acceptable salts,
thereo~, these compounds being in the form of a mixture
or in the form of the individual isomers; the correspond-
6~2~
-- 6 --
ing 8~0,N-dipivaloyl derivative i~ especially preferred.
The novel compounds of the formula I can be manu-
factured in a manner known per se, for example by
treating a compound of the formula
~H3 ~H3 ~H3
; H3CCoO~ 9
H
¦ 3 \.~ ~o,Q.~ (II)
CH2~ R
~Ç~O ~ ._. , .=,
~H3 ~13
with an acylating agent that introduces a tri-lower
alkylmethylcarbonyl radical Rl and R2 or R1 and R3 into
position 8, and into position 21 or the ring amid~
nitrogen atom, and, if desired, separating a mixture of
isomers obtained according to the process, and/or
converting a salt obtained according to the process into
; the ~ree compound or into a different salt, and/or
. converting a free compound obtained according to the~ process into a salt.
:~ The introduction o~ the tri-lower alkylm~thyl-
carbonyl radicals Rl and R2 or Rl and R3 into the desired
positions can be carried out in a manner known per se
using a customary.aoylating agent suitable for the
introduction of such radical~, at least two equivalents
of the latter being used. It is possible to use r for
example, a corresponding carboxylic acid, if necessary in
the presence of a suitable condensation agent, such as
dicyclohexylcarbodiimide, but preferably a reactive
derivative of such a carboxylic acid, such as an an-
hydride, especially a mixed anhydride, such as one with
an inorganic acid, such as a hydrohalic acid, especially
hydrochloric acid or hydrobromic acid (that is to say a
~'
.... . . .
,.. .
67~
-- 7 --
corresponding acid halide, ~or example chloride), or with
an organic acid, such as trifluoroacetic acid or a
suitable mono-ester of carbonic acid, or alternatively a
symmetric anhydride, or an internal anhydride, that is
to say the corresponding ketene.
The derivative of a carboxylic acid employed as
acylating agent is preferably used in th~e presence of a
basic agent; a suitable basic agent is especially a non-
acylatable organic base, such as a heteroaromatic base,
Eor example pyridine, collidine or guinoline, a tertiary
amine, for example triethylamine, N-e~hylpiperidine, N-
methylmorpholine or 1,4-dimethylpiperazine, or 1,5-
diazabicyclo[s,4,0]undec-s-ene.
The acylation reaction is generally carried out i.n
the presence o~ a solvent or diluent, it being possible
to use as such an eXcess of the acylating agent or of the
base, for example pyridine, used together with an
acylating agent. Other solvents, which can be used, for
example, also in admixture with a base, are, for example,
non-acylatable organic solvents, such as hydrocarbons,
for example pentane, hexane or cyclohexane, halogenated
hydrocarbons, for example methylene chloride or chloro-
form, ethers, for example diethyl ether, eth~lene glycol
dimethyl ether, tetrahydrofuran or dioxan, acid esters,
for example ethyl acetate, and acid amides, for example
acetamide or dimethylformamide.
The reaction is generally carried out at room
temperature or at slight~y elevated temperatures, for
example at up to approximately 70C, the operation being
carried out, if necessary, under an inert gas atmosphere.
The acylation conditions, especially the amount of acyl-
ating agent used, the reastion medium, the temperature
and the reaction time, should be so chosen that both acyl
groups are introduced, the procedure preferably being in
accordance with the methods illustrated in more detail in
the Examples. The course of the reaction can advant-
..
ageously be followed by means of customary analyticalmethods, especially by means of thin layer chromato-
graphy.
The working-up of the reaction product from the
reaction mixture obtained according to the process is
carried out in a manner known er se, for example by
dilution with water and/or optionally by neutralisation
or slight acidification (up to approximately pH ~) with
an aqueous acid, such as an inorganic or organic acid,
for example a mineral acid or, advantageously, citric
acid, and by the addition of a water-immiscible solvent,
such as a chlorinated hydrocarbon, for example chloroform
or methylene chloride, the reaction product passing into
the organic phase from which it can be obtained in
purified form in customary manner, for example by
drying, concentration of the solvent by evaporation and
crystallisation and/or chromatography of the residue, or
by other customary methods of purification.
The above reaction generally yields a mixture of the
two diacylated compounds, the 8-O,N-diacylated compound
normally predominating. The mixture can be separated in
a manner known ~er se, for example by means of fractional
crystallisation, chromatography, etc., into the desired
individual diacyl compounds.
The starting materials of the formula II are known
and can be manufactured in a manner known ~E se;
reference is made, for example, to the PCT application
having the publication no. ~O 87/02361.
The compounds o~ the present invention can form acid
addition salts, especially pharmaceutically acceptable
acid addition salts, with inorganic or organic acids.
These are, inter alia, hydrohalic acids, for example
hydrochloric and hydrobromic acid, sulphuric acid,
phosphoric acid, nitric acid or perchloric acid, or
aliphatic, carbocyclic (especially aromatic) or hetero-
cyclic carboxylic or sulphonic acids, such as formic,
~, ..
~ ~67~
g
acetic, propionic, succinic, glycolic, lactic, malic,
tartaric, citric, fumaric, maleic, hydroxymaleic,
pyruvic, phenylacetic, benzoic, -aminobenzoic, anthra-
nilic, ~-hydroxybenzoic, salicylic, ~-aminosalicylic or
embonic acid, also methanesulphonic, ethanesulphonic,
hydroxyethanesulphonic, ethylenedisulphonic, halobenzene-
sulphonic, toluenesulphonic and naphthallenesulphonic
acid or sulphanilic acid, also methionine, tryptophan,
lysine or arginine, and ascorbic acid.
The formation of the salts and the conversion of
salts into the free compounds are carried out in a manner
known ~E se. For example, the acid addition salts are
obtained by treatment with an acid suitable for salt
formation, such as one o~ those mentioned above, while
salts can be converted into the free compounds by
treatment with basic agents, such as inorganic
hydroxides, carbonates and hydrogen carbonates, or
organic bases and ion exchangers. These salts with the
above-mentioned acids, or other salts, such as, for
example, oxalates or picrates, can also be used for the
purification of the resulting compounds by converting the
free compounds into salts, separating these off and
recovering the free compounds from the salts again.
owing to the close relationship between the compounds in
free form and in the form of their salts, hereinbefore
and hereinafter the free compounds should be understood
as meaning also the corresponding salts, where appro-
priate and expedient.
The invention relates also to those forms of the
process according to ~Thich a starting material is used in
the form of a derivative, for example a salt, or is
formed under the reaction conditions.
In the processes o~ the present invention, it is
preferable to use those starting materials which result
in the compounds described at the beginning as being
especially valuable.
~2~672~
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The present invention also includes the use of the
compo~nds of the formula I and their salts, alone or
together with adjuncts, and also in combination with
other active ingredients, as agents for the therapeutic
(both curative and preventive) treatment of diseases or
pathological conditions that are indicated or caused, for
example, by an elevated content of cholesterol and/or
triglycerides in the blood, especially in the blood
serum. The active ingredients according to the invention
are administered in therapeutically effective amounts,
preferably in the form of pharmaceutical compositions
together with customary pharmaceutical carrier materials
and/or adjuncts, to the warm-blooded animal requiring
treatment, especially man. Depending on the species,
body weiyht, age and individual condition, and depending
on the mode of administration and especially also on
individual condition, there are administered, for
example, to warm-blooded animals daily doses correspond-
ing to from approximately 1 to approximately 100 mg,
especially from approximately 3 to approximately 50 mg,
per kg body weight, which doses can be exceeded in severe
cases. Accordingly, the invention also includes the
corresponding method of medical treatment.
The invention relates, in addition, to pharmaceut-
ical compositions that contain the compounds of the
present invention as active ingredients, and to processes
for their manufacture.
The pharmaceutical preparations according to the
invention are for enteral, such as peroral or rectal,
administration, and also for parenteral administration to
warm-blooded animals. Corresponding dosage unit forms,
especially for peroral administration, for example
dragées, tablets or capsules, contain preferably from
approximately 50 to approximately 500 mg, especially from
approximately 100 to approximately 300 mg, of the active
ingredient together with pharmaceutically acceptable
;
:~2~167:~
carriers and/or adjuncts.
Suitable carriers are especially fillers, such as
sugars, for example lactose, saccharose, mannitol or
sorbitol, cellulose preparations and/or calcium phos-
phates, for example tricalcium phosphate or calcium
hydrogen phosphate, also binders, such as starch pastes
prepared, for example, from corn, wheat, rice or potato
starch, gelatine, tragacanth, methylcellulose and/or, if
desired, disintegrators, such as the above-mentioned
starches, also carboxymethyl starch, cross-linked
polyvinylpyrrolidone, agar, alginic acid or a salt
thereof, such as sodium alginate. Adjuncts are especial-
ly flow-regulating agents and lubricants, for example
silica, talc, stearic acid or salts thereof, such as
magnesium or calcium stearate, and/or polyethylene
glycol. Dragée cores may be provided with suitable
coatings that may be resistant to gastric juices, there
being used, inter alia, concentrated sugar solutions that
may contain gum arabic, talc, polyvinylpyrrolidone,
polyethylene glycol and/or titanium dioxide, or lacquer
solutions in suitable organic solvents, or, for the
manufacture of coatings resistant to gastric juices,
solutions of suitable cellulose preparations, such as
acetylcellulose phthalate or hydroxypropylmethylcellulose
phthalate. Colourings or pigments may be added to the
tablets or dragée coatings, for example for identifi-
cation purposes or to indicate different doses of active
ingredient.
Further orally administrable pharmaceutical prepara-
tions are dry-filled capsules consisting of gelatine and
also soft sealed capsules consisting of gelatine and a
plasticiser, such as glycerol or sorbitol. The dry-
filled capsules may contain the active ingredient in the
form of a granulate, for example in admixture with
fillers, such as lactose, binders, such as starches,
and/or glidants, such as talc or magnesium stearate, and
~2~
- 12 -
optionally stabilisers. In soft capsules, the active
ingredient is preferably dissolved or suspended in
suitable liquids, such as fatty oils, paraffin oil or
liquid polyethylene glycols, to which stabilisers may
also be added.
Suitable rectally administrable pharmaceutical
preparations are, for example, suppositories that
consist of a combination of the active ingredient and a
suppository base material. Suitable suppository base
materials are, for example, natural or synthetic tri-
glycerides, paraffin hydrocarbons, polyethylene glycols
or higher alkanols.
Suitable for parenteral administration are especial-
ly aqueous solutions of an active ingredient in water-
soluble ~orm, ~or example a water-soluble salt, or
aqueous injection suspensions that contain viscosity-
increasing substances, for example sodium carboxymethyl-
cellulose, sorbitol and/or dextran, and optionally
stabilisers. The active ingredient, optionally together
with adjuncts, can also be in the form of a lyophilisate
and can be dissolved by the addition of suitable solvents
before parenteral administration.
The pharmaceutical preparations of the present
invention can be manufactured in a manner known eer se,
for example by means of conventional mixing, granulating,
confectioning, dissolving or lyophilising processes.
For example, pharmaceutical preparations for oral use can
be obtained by combining the active ingredient with solid
adjuncts, optionally granulating a resulting mixture and
processing the mixture or granulate, if desired or
necessary after the addition of suitable adjuncts, to
form tablets or dragée cores.
The following Examples illustrate the invention
described above but do not limit its scope in any way.
Temperaturea are given in degrees Celsius.
~2~672~
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Example 1: 8-O,N- and 8-0,21-0-dipivaloyl-3-[4-(2,4,6-
trimethylbenzyl)-1-piperazinyl]-rifamycin S
35.5 ml of pivaloyl chloride (10.5 equivalents) are
added dropwise to a solution of 25 g of 3-[4-(2,4,6-
trimethylbenzyl)-l-piperazinyl]-rifamycin S in 250 ml of
pyridine and the whole is stirred for 8 hours at room
temperature until the starting material can no longer be
detected in a thin-layer chromatogram. 150 ml of
methanol are then added to the solution and the whole is
stirred for 1 hour at room temperature in order to
decompose excess pivaloyl chloride and is then con-
centrated to dryness by evaporation. The residue is
taken up in 300 ml o~ methylene chloride, the solution is
filtered and the filtrate is extracted with 300 ml of
water. The aqueous phase is adjusted to pH 3 to 4 with
lN hydrochloric acid and extracted three times with
methylene chloride. The combined methylene chloride
extracts are washed three times using 100 ml of water
each time, dried, and concentrated to dryness by evapora-
tion. The residue is applied to a column of 1000 g of
silica gel and eluted with a 1:4 mixture of ethyl acetate
and cyclohexane. The first fractions contain the 8-0,21-
0-dipivaloyl-3-[4-(2,4,6-trimethylbenzyl)-1-piperazin-
yl)-rifamycin S which is obtained in the form of violet-
brown crystals having a melting point of 135-145C
(decomposition) by further chromatography on silica gel
and crystallisation from diethyl ether. The subsequent
fractions ccntain the main product of the reaction:
8-O,N-dipivaloyl-3-t4-(2,4,6-trimethylbenzyl)-1-piper-
azinyl]-rifamycin S which, when crystallised from diethyl
ether, forms reddish-violet crystals having a melting
point of 157-163C.
~Z~672~
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Physical characteristics:
a) 8-0,21 0-dipivaloyl compound: :
ultraviolet absorption spectrum
(in ethanol) [ ~ max (~)]: 218 (36400), 258
(shoulder), 318 (shoulder), 354 (8800), 517 (1800) nm.
mass spectrum: m/e = 1080 (M+ + H) in accordance with the
empirical formula C61H81N3O14.
lH-NMR (in CDC13) [ppm (allocation)]:
6.83 s (2H at the aromatic ring of the benzyl
radical)
5~2 dd (H-21)
2.37l s (aromatically bonded methyl groups)
2.27J
3.48 AB (methylene of the benzyl radical)
1.47} s (methyl groups of the pivaloyl radicals)
1.42
0.95~
0.85 s (4H of methyl groups or ansa ring)
0.70
0.18
13C-NMR (in CDC13) [ppm (allocation)]:
179.2 lC ~pivaloyl-carbonyl)
176.8 lC (pivaloyl-carbonyl)
27.3 3C~ (methyl groups of the pivaloyl radicals)
27.2 3CJ
~L2~
- 15 -
53.2 2Cl (methylene groups of the piperazine
49.0 2Cj radical~
56.0 lC (methylene of the benzyl radical)
173.5 2C
135.6 lC
131.1 lC (trimethylphenyl)
128.6 2C
20.4 3C
b) 8-O,N-dipivaloyl compound:
ultraviolet absorption spectrum
~in ethanol) [J~ max(~)]: 264 (31880), 320 (shoulder),
350 (shoulder), 524 (2200) nm.
mass spectrum: m/e = 1080 (M+ + H) in accordance with the
empirical formula for C61H81N314-
infra-red absorption spectrum
(in CH2Cl2): 3500, 2g60, 2940, 1735, 1710, 1640, 1600,
1565 cm 1, no amide-NH- present.
H-NMR (CDCl3) ~ppm (allocation)]:
6.83 s (2H of the aromatic ring of the benzyl
radical)
3.45 ` AB (methylene of the benzyl radical)
3.05 m (H-21~ ~
(3 methyl groups at the benzyl radical)
2.26 J
1.48 ~ s (6 methyl groups of the pivaloyl)
1.44 J
~;
,~` ..
6~
- 16 -
1.07
0.96 d (4H of methyl groups or ansa ring)
0.81
0.24
13C_NHR (in CDCl3):
190.4 lC (pivaloyl-carbonyl)
179.0 lC (pivaloyl-carbonyl)
4~.3 lC (quaternary C of the pivaloyl radicals)
40.5 lC (quaternary C of the pivaloyl radicals)
29.4 3C (3 methyl groups of the pivaloyl radicals)
27.7 3C (3 methyl groups of the pivaloyl radicals)
52.5 2C ¦ (4 methylene groups of the piperazine)
50.2 2C J radical)
54.9 lC (methylene of the benzyl radical)
137.5 2C
135.7 lC
131.3 lC (2,4,6-trimethylphenyl)
128.7 2C I
; 19.7 3C J
The starting material can be obtained in the following
manner:
a) 30 g of N-(2,4,6-trimethylbenzyl)-piperazine are
added to a solution of 50 g of rifamycin S in 500 ml of
dioxan and the whole is left to stand at room temperature
for 18 hours. The mixture is then acidified by the
addition of a 10% aqueous citric acid solution and the
reaction product is taken up in methylene chloride.
After the methylene chloride extract has been dried and
concentrated by evaporation, the dark coloursd residue is
.~
dissolved in ethanol, and then aqueous ascorbic acid is
added dropwise thereto. The 3-[4-(2,4,6-trimethyl-
benzyl)-l-piperazinyl~-rifamycin SV is obtained in the
form of yellow crystals having a melting point of 178-
181C (partial decomposition).
b) A solution of 10 g of the product prepared according
to a) in 200 ml of methylene chloride is stirred inten-
siv~ly for 5 minutes with 10 g of finely ground manganese
dioxide. The solid portions are filtered off and the
filtrate is concentrated to dryness by evaporation,
yielding the amorphous blue-black 3-[4-(2,4,6-trimethyl-
benzyl)-l-piperazinyl]-rifamycin S which is processed
further without further purification.
Example 2: 8-O,N-dipivaloyl-3-[4-(2,6-dimethyl-4-
tert.-butylbenzyl)-l-piperazinyl]-
rifamycin S
In a manner analogous to that described in Example
1, starting from 3-[4-(2,6-dimethyl-4-tert.-butyl-
benzyl)-l-piperazinyl]-rifamycin S, the title compound
is obtained in the form of a solid without a clearly
defined melting point;
mass spectrum: m/e = 1121 (M~) in accordance with the
empirical formula for C64H87N314;
ultraviolet absorption spectrum
(in ethanol) [ ~ max (~)]: 263 (29960); 324 (shoulder);
360 (shoulder); 526 (2000) nm.
infra-red absorption spectrum
(in methylene chloride): 3500, 2970, 1735, 1675, 1640,
1600, 1570 cm~l.
.
:L2~6~
- 18 -
1H-NMR (in CDC13) ~ppm (allocation)]:
7.00 s (2H at the aromatic ring of the benzyl
; radical)
3.43 AB (methylene of the benzyl radical)
2.35 s (3 methyl groups at the aromatic ring)
1.48 ~ s (6 methyl groups of the pivaloyl radicals)
1.44 J
The starting material can be manufactured in the
following manner:
3 g of N-(2,6-dimethyl-4-tert.-butylbenzyl)-
piperazine are added to a solution of 5 g o~ 3-bromo-
rifamycin S in 50 ml of tetrahydrofuran and the whole is
left to stand for 3~ minutes at 20. The mixture is
then acidified by the addition of aqueous citric acid
solution and the reaction product is taken up in methyl-
ene chloride. After the methylene chloride extract has
been dried and concentrated by evaporation, a dark-
coloured residue remains behind; the residue is dissolved
in methanol, and aqueous ascorbic acid is added dropwise
thereto. The 3-[4-(2~6-dimethyl-4-tert.-butylbenzyl)
piperazinyl]-rifamycin SV is obtained in the form of
yellow-coloured crystals, melting point 260. Treatment
with manganese dioxide as described under b) in Example 1
yields the desired starting material of the S series.
Exam~le 3:
In analogous manner it is possible to obtain the
following compounds of the formula I:
8-0,2I-0-di-(2,2-dimethylbutyryl)-3-[4-(2,4,6-trimethyl-
benzyl)-l-piperaæinyl)-rifamycin S and
8-O,N-di-(2,2-dimethylbutyryl)-3-~4-~2,4,6-trimethyl-
benzyl)-1-piperazinyl~-rifamycin S or a mixture thereof;
~67~
-- 19 --
8-0,21~0-di-~2-ethyl-2-methylbutyryl)-3-[4-(2,4,6-
trimethylbenzyl)-l-piperazinyl]-rifamycin S and
8-O,N-di-(2-ethyl-2-methylbutyryl~-3-[4-(2,4,6-trimethyl-
benzyl)-1-piperazinyl]-rifamycin S or a mixture thereof;
8-0,21-0-di-(2,2-diethylbutyryl)-3-[4-(2,4,6-trimethyl-
benzyl)-1-piperazinyl]-rifamycin S and
8-O,N-di-(2,2-diethylbutyryl)-3-[4-(2,4,6-trimPthyl-
benzyl)-l-piperazinyl~-rifamycin S or a mixture thereof;
8-0,21-0-di-(2,2-dimethylvaleryl)-3-[4-(2,4,6-trimethyl-
benzyl)-1-piperazinyl]-rifamycin S and
8-O,N-di-(2,2-dimethylvaleryl)-3-[4-(2,4,6-trimethyl
benzyl)-l-piperazinyl~-rifamycin S or a mixture thereof;
8-0,21-0-di-f2-ethyl-2-methylvaleryl)-3-[4-(2,4,6-
trimethylbenzyl~-l-piperazinyl]-rifamycin S and
8-O,N-di-(2-ethyl-2-methylvaleryl)-3-[4-(2,4,6-trimethyl-
benzyl)-l-piperazinyl]-rifamycin S or a mixture thereof;
8-0,21-0-di-(2,2-diethylbutyryl~-3-[4-(2,6-dimethyl-4-
tert.-butylbenzyl)-l-piperazinyl]-rifamycin S and
8-O,N-di-(2,2-diethylbutyryl)-3-[4-(2,6-dimethyl-4-tert.-
butylbenzyl)-l-piperazinyl]-rifamycin S or a mixture
thereof .
'~
~21'3~
- 20 -
Example 4: Capsules containing 250 mg of 8-O,N-di-
pivaloyl-3~[4-(2,4,6-trimethylbenzyl)-l-piperazinyl]-
rifamycin S can be manufactured as follows:
Composition (for 1000 capsules):
8-O,N-dipivaloyl-3-[4-(2,4,6-trimethyl-
benzyl)-l-piperazinyl~-rifamycin S 250.0 g
corn starch 50.0 g
polyvinylpyrrolidone 15.0 g
magnesium stearate 5.0 g
ethanol q.s.
The active ingredient and the corn starch are mixed
together and moistened with a solution of the polyvinyl-
pyrrolidone in 50 g o~ ethanol. The moist mass i~
pressed through a sieve having a mesh width of 3 mm and
dried at 45. The dry granulate is passed through a
sieve of 1 mm mesh width and mixed with 5 g of magnesium
stearate. 0.320 g portions of the mixture are intro-
duced into size 0 dry-fill capsules.
In analogous manner it is also possible to use
8-0,21-O-dipivaloyl-3-[4-(2,4,6-trimethylbenzyl)-1-
piperazinyl~-rifamycin S or a mixture thereof with the
corresponding 8-Q,N-dipivaloyl compound.
Example 5: 250 g of an active ingredient according to
Example 1 or 2 and 1750 g of finely ground suppository
base material (for example cocoa butter) are thoroughly
mixed and then melted. 1000 suppositories of 2 g are
cast from the melt which is kept homogeneous by stirring.
Each suppository contains 250 mg of active ingredient.
. ~. ..
