Pleuromutilin derivatives process for their preparation and their use

A compound of formula I ##STR1## wherein R.sub.1 represents ethyl or vinyl and PA1 R.sub.2 represents a five membered saturated heterocycle or aminoalkyl unsubstituted or substituted in its alkyl moiety by hydroxy, in free or in the form of an acid addition or quaternary salt, which compounds are indicated for use as chemotherapeutic agents e.g. as anti-bacterially active antibiotics and as veterinary agents e.g. in combatting microorganism infections and promoting growth in domestic animals.

The present invention concerns derivatives of 
14-0-[(1-Amino-2-methylpropan-2-yl)thioacetyl]-mutilin and 
-19,20-dihydro-mutilin. In particular it concerns an 
N-Acyl-14-0-[(1-amino-2-methylpropan-2-yl)thioacetyl]-mutilin or 
-19,20-dihydro-mutilin. 
More particularly the invention concerns compounds of formula I 
##STR2## 
wherein R.sub.1 represents ethyl or vinyl and 
R.sub.2 represents a five membered saturated heterocycle or aminoalkyl 
unsubstituted or substituted in its alkyl moiety by hydroxy, 
in free form or in the form of an acid addition or quaternary salt. 
The compounds of the invention may be obtained by acylating 
14-0-[(1-Amino-2-methylpropan-2-yl)thioacetyl]mutilin or 
-19,20-dihydromutilin and more particularly by reacting a compound of 
formula II 
##STR3## 
with a reactive ester of a compound of formula III 
EQU HOOCR.sub.2 ' III 
whereby R.sub.2 ' has the same meaning as R.sub.2 above except that any 
amino groups present therein are protected, deprotecting any protected 
amino groups and recovering the compound thus obtained in free form or in 
the form of an acid addition salt or a quaternary salt. 
This process according to the invention can be carried out by dissolving or 
suspending a compound of formula II and a compound of formula III in a 
solvent inert under the reaction conditions e.g. in a 
di(lower)alkylcarboxylic acid amide such as dimethylformamide, and 
allowing the reaction to proceed at room temperature or at a raised 
temperature preferably at room temperature. The subsequent splitting-off 
of protecting groups can be carried out according to conventional methods 
for example by reductive deprotection with Pd/active charcoal and hydrogen 
or by treatment with trifluoroacetic acid. The final products can be 
isolated from the reaction mixture and if necessary purified according to 
conventional methods. 
The compounds of formula I can be converted into their acid addition salts 
and vice versa in conventional manner. Corresponding quaternary salts can 
be obtained from the compounds of formula I in conventional manner. 
The compounds of formula I may contain at least one asymmetric carbon atom 
and may thus exist in the form of diastereomeric isomers and mixtures 
thereof which may be separated in conventional manner. Use of optically 
active starting materials will lead to the corresponding end products. The 
invention concerns both isomers and mixtures thereof and reference is made 
to the latter unless otherwise stated. 
The compounds of formula I exhibit interesting biological in particular 
chemotherapeutical activity and are therefore useful as medicaments. They 
display an inhibitory activity against bacteria as determined in tests in 
vitro with the series dilution test using various bacterial strains e.g. 
Staph. aureus, Staph. epidermidis, Strept. pyogenes, Strept. pneumoniae, 
E. coli, Klebsiella pneumoniae, Haemophilus spp., Leptospiren spp., 
Erysipelothrix rhusiophathiae and obligatory anaerobes, e.g. Bacteroides 
fragilis from a concentration of ca. 0.008 to 25 .mu.g/ml. In particular 
an inhibitory activity was also found against Mycoplasms and Chlamydia 
which exhibits itself from a concentration of ca. 0.008 to 0.5 .mu.g/ml. 
The chemotherapeutic activity of the compounds was established through 
tests on mice, using various bacterial strains, and on hens, using 
mycoplasma strains. This inhibitory activity was observed from a 
concentration of ca. 12 to 50 mg/kg of body weight. The compounds 
according to the invention can therefore be used as anti-bacterially 
active antibiotics. 
In addition the above mentioned compounds display an anti-parasitic 
activity, in particular against coccidia as well as a growth promoting 
activity. To establish the activity against coccidia testing took place in 
vivo on the hen. The activities can be confirmed in these animal tests at 
dosages of 20-150 mg/kg of feed depending upon the period of application. 
The growth promoting properties were established in hen and pig in a 
dosage range of 10-50 mg/kg feed. The compounds of formula I are therefore 
suitable as veterinary agents in particular for the chemotherapeutic 
treatment of coccidioses in fowl as well as growth promoters in the animal 
species mentioned. 
In use, the effective dosage will, of course, vary depending on the 
particular compound employed, the mode of administration and the treatment 
desired. However, in general, satisfactory results as anti-baterials and 
anti-anaerobics can be obtained when the compounds are administered at a 
daily dosage of from about 10 to 300 mg/kg of animal body weight, suitably 
given in divided doses two to four times daily. For most large mammals, 
the total daily dosage is from about 1 g to 3 g, and dosage forms suitable 
for internal administration comprise about 250 to 1500 mg of the compound 
in admixture with a solid or liquid pharmaceutical carrier or diluent. 
For the prophylaxis or therapy of microorganism infections and for growth 
promotion in domestic animals, the dosage will of course vary depending 
upon the size and age of the animal and the effect desired; for example 
for prophylactic treatment relatively low doses would be administered over 
a long time. Preferred doses in drinking water are from 0.0125 to 0.05 
weight by volume, particularly 0.0125 to 0.025, and in foodstuffs from 20 
to 400 g/metric ton, particularly 20 to 200 g/metric ton. It is preferred 
to administer the active compound to hens in drinking water, and to pigs 
in the foodstuff. 
The compounds may be used in free base form or in the form of 
chemotherapeutically/physiologically acceptable acid addition and 
quaternary salts. Such salt forms exhibit the same order of activity as 
the free base forms. 
Examples of suitable acid addition salts are the hydrogen fumarate, 
fumarate, naphthalin-1,5-sulphonate and especially the hydrochloride. 
The compounds may be administered orally, locally or parenterally and 
admixed with conventional chemotherapeutically acceptable diluents and 
carriers, and, optionally, other excipients and administered in such forms 
as tablets, capsules or injectable preparations. 
The compounds also form excellent additives for feed mixes (as premix) or 
for drink water as well as for diluting fluids for artificial insemination 
and for egg-dipping techniques. 
Such compositions also form part of the invention. 
The invention therefore also concern a method of combatting bacteria and 
obligatory anaerobes comprising administering to a subject in need of such 
treatment an effective amount of a compound of formula I or a 
chemotherapeutically acceptable acid addition or quaternary salt thereof 
and such compounds for use as chemotherapeutic agents, in particular 
anti-bacterially active antibiotics and agents against infections caused 
by obligatory anaerobes. 
The invention further provides a method of combatting microorganism 
infections and promoting growth in domestic animals which comprises 
administering to a subject in need of such treatment an effective amount 
of a compound of formula I or a physiologically acceptable acid addition 
or quaternary salt thereof and such compounds for use in combatting 
coccidia and promoting growth in domestic animals. 
The starting materials of formula II are new and may be obtained by 
reacting a compound of formula IV 
##STR4## 
wherein R.sub.1 is as defined above and R.sub.5 stands for chlorine, 
bromine or a O.SO.sub.2.R.sub.6 group, wherein R.sub.6 represents alkyl or 
aryl, with the compound of formula V 
##STR5## 
This reaction can be carried out for example by dissolving the compound of 
formula V in a solution of sodium in an anhydrous lower alcohol e.g. in 
ethanol or methanol. To this solution is then added a solution of a 
compound of formula IV in a solvent inert under the reaction conditions 
e.g. in an aliphatic ketone such as ethylmethylketone or acetone. The 
reaction proceeds preferably at room temperature up to boiling temperature 
of the reaction mixture, especially 25.degree. to 55.degree. C. 
The starting materials of formula III, IV and V are either known or are 
preparable analogously to known methods e.g. for compounds V as described 
in F. J. Carroll, J. D. White and M. E. Wall, J. Org. Chem. 28/1240 
(1963). 
Alkyl groups appearing as substituents preferably represent lower alkyl 
groups, especially with 1 to 4 carbon atoms. When R.sub.2 stands for a 
heterocycle then this may contain one or two heteroatoms, whereby one 
heteroatom is nitrogen and the optionally present second heteroatom is 
sulphur. 
Protecting groups for the amino function in the starting materials of 
formula III include those commonly used as amino-protecting groups, for 
example --CO.O.CH.sub.2.C.sub.6 H.sub.5 (Z), --CO.O.C(CH.sub.3).sub.3 
(BOC) or --CO.O.CH.sub.2 CCl.sub.3. 
Preferred substituent meanings are 
R.sub.1 = 
(a) ethyl 
(b) vinyl whereby vinyl is especially preferred 
R.sub.2 = 
(a) aminoalkyl 
(b) aminohydroxyalkyl 
(c) as (a) or (b) with alkyl having C.sub.1-6 especially C.sub.1-4 
(d) 5-membered saturated heterocycle 
(e) 5-membered saturated heterocycle containing one N atom and optionally 
one S atom. 
Combinations of these groups are especially preferred. 
A particularly preferred individual compound is 
14-0-[1(2-Amino-3-methyl-butyrylamino)-2-methyl-propan-2-yl-thioacetyl]-mu 
tilin as free base or hydrochloride, preferably in (D)-Form. 
In the following examples which illustrate the invention but in no way 
limit its scope, references to temperature are in degrees celsius.