Derivatives of midecamycine

Abstract

Novel derivatives of midecamycine, of the formula: ##STR1## wherein X represents an oxygen atom or a sulphur atom, R.sub.1 represents a straight or branched alkyl group, an alkenyl group or an aryl group, R.sub.2 represents a hydrogen atom or a lower acyl group, the dotted lines represent the possible presence of double bonds, it being understood that the 2 double bonds at the 10,11 position on the one hand and the 12,13 position on the other either exist simultaneously or neither of them exists, which give by oral administration plasma rates which are higher than midecamycine and which lack its bitter taste, together with their process of preparation.

Description

The present invention relates to derivatives of an antibiotic given the name Midecamycine and corresponding to the formula: ##STR2##

The invention seeks to provide substances having an antibiotic activity which is utilisable in human or veterinary medicine.

The new compounds correspond to the general formula: ##STR3## in which X represents an O or S atom, R.sub.1 represents a straight or branched alkyl group, an alkenyl group or an aryl group, and R.sub.2 represents an H atom or an acyl group.

The broken lines indicate the possible presence of double bonds, it being understood that the two double bonds 10,11 on the one hand and 12,13 on the other either exist simultaneously or neither of them exists.

These new compounds have the following important advantages in comparison with Midecamycine:

They have in vitro at least equal activity as regards various Gram.sup.+ bacteria;

In vivo, they give in equal dosages a better protection against experimental disorders;

They provide higher plasmatic rates after administration orally;

They lack the very strong bitter taste of Midecamycine.

The compounds (I) in which R.sub.2 = H are obtained from Midecamycine by the action in pyridine of a chloroformate or thiochloroformate of the formula: ##STR4## where X represents an O or S atom and R.sub.1 is as defined above, at a somewhat elevated temperature (0.degree.-25.degree. C.).

By replacing Midecamycine with tetrahydromidecamycine, a known compound, the derivatives (I) are obtained which do not have double bonds at 10,11 and 12,13. Isolation of the compounds is effected by dilution with water, followed by extraction with a suitable organic solvent such as ethyl acetate. The crude product so obtained, if it appears necessary, can be purified by chromatography on silica or alumina followed, if required, by crystallisation from an appropriate solvent.

The compounds (I) in which R.sub.2 = acyl are obtained from compounds in which R.sub.1 = H by the action of the acid anhydride (R.sub.2 CO).sub.2 O in pyridine under reflux.

The following examples illustrate the results obtained:

EXAMPLE 1

9-Methoxycarbonyl midecamycine of Formula (I) above, in which R.sub.1 = CH.sub.3, X = O, R.sub.2 = H.

15 g of Midecamycine was dissolved in 120 ml of pyridine and then the solution was cooled in an ice bath and 30 ml of methyl chloroformate was added dropwise. After the end of the addition, the mixture was left for 24 hours under agitation at the ambient temperature. The solution was diluted with 500 ml of water and then extracted 3 times with 150 ml of ethyl acetate.

The organic phase was successively washed:

with a dilute hydrochloric solution until the pH of the wash solutions equalled 4; with 150 ml of a saturated sodium bicarbonate solution; with 150 ml water; with 150 ml of saturated sodium chloride solution.

The solution dried over magnesium sulphate was then evaporated to dryness under vacuum.

The residuary oil (13 g) was chromatographed on a silica column (200 g). Elution was first effected with (19/1) benzene-acetone mixture, which allowed various imurities to be eliminated, and then with a (4/1) benzene-acetone mixture, which provided 7.5 g of the crude product.

To obtain the product substantially pure, the crude product was dissolved in 50 ml of benzene. The solution was placed in a 250 ml flask and the solution was frozen by cooling in liquid nitrogen in contact with all the walls of the flask. The flask was then subjected to low vacuum (p <0.1 mm of mercury) and the flask was then removed from the liquid nitrogen, the cold produced by the evaporation being sufficient to maintain the mass in the solid state.

______________________________________Analysis: Calculated C : 59.22 H : 7.98 N : 1.66Found 59.84 7.94 1.57______________________________________

The infrared spectrum in solution in chloroform shows a strong band at 1275 cm.sup.-1 characteristic of the asymetric O--C--O group.

EXAMPLE 2

9-Ethoxycarbonyl midecamycine of Formula I above, in which R.sub.1 = C.sub.2 H.sub.5, X = O, R.sub.2 = H.

Operating according to Example 1 using 15 g of Midecamycine, the methyl chloroformate was replaced with an equivalent quantity of ethyl chloroformate. The material was trated as indicated in Example 1; however the greater purity of the product did not require chromatography on silica. Finally, after evaporation of the benzene solution was previously indicated, a solid residue (13 g) was obtained. M.P. = 121.degree. C.

______________________________________Analysis: Calculated C : 59.64 H : 8.09 N : 1.58 Found 59.61 8.02 1.70______________________________________ IR spectrum (potassium bromide tablet), strong band at 1260 cm.sup.-1.

EXAMPLE 3

Butoxycarbonyl midecamycine of Fromula I above, in which R.sub.1 = C.sub.4 H.sub.9, X = O, R.sub.2 = H.

Operating according to Example 1, the methyl chloroformate was replaced with butyl chloroformate. By the same treatment, a yellow powder (12 g) was obtained, M.P. = 75.degree. C.

______________________________________Analysis: Calculated C : 60.44 H : 8.27 N : 1.53 Found 60.55 8.46 1.39______________________________________ IR spectrum (potassium bromide tablet), strong band at 1260 cm.sup.-1.

EXAMPLE 4

9-Isobutoxycarbonyl midecamycine of Formula I, in which R.sub.1 = i-C.sub.4 H.sub.9, X = O, R.sub.2 = H.

Operating according to Example 1, the methyl chloroformate was replaced with isobutyl chloroformate. By the same treatment, a powder (8.4 g) was obtained, M.P. = 114.degree. C.

______________________________________Analysis: Calculated C : 60.44 H : 8.27 N : 1.53 Found 60.45 8.24 1.47______________________________________

EXAMPLE 5

9-Phenoxycarbonyl midecamycine of Formula I in which R.sub.1 = C.sub.6 H.sub.5, X = O, R.sub.2 = H.

4.06 g of Midecamycine was dissolved in 70 ml of acetone and 1.38 g of pyridine was added, then slowly a solution of 4.7 g of phenyl chloroformate in 30 ml of acetone. After the end of the addition, the mixture was left for 16 hours at the ambient temperature and then the mixture was poured into 500 ml of water. This was rendered alkaline to pH 8 by the addition of a 15% caustic soda solution and extracted 3 times with 200 ml of ethyl acetate. The organic solution was washed twice with 200 ml of saturated sodium chloride solution and then dried over magnesium sulphate and the solvent was evaporated under reduced pressure.

The residuary oil was chromatographed on a silica column and eluated with a (5/1) benzene-acetone mixture. 4 g of the product was thus obtained, which crystallised. After recrystallisation from petroleum ether, M.P. = 126.degree. C.

______________________________________Analysis: Calculated C : 61.72 H : 7.66 N : 1.50 Found 61.57 7.67 1.25______________________________________ IR spectrum (in solution in chloroform), strong band at 1265 cm.sup.-1.

EXAMPLE 6

9-Allyloxycarbonyl midecamycine of Formula I in which R.sub.1 = CH.sub.2 = CH--CH.sub.2, X = O, R.sub.2 = H.

Operating as in Example 1, the methyl chloroformate was replaced with allyl chloroformate. A white powder (9.6 g) was obtained, M.P. = 97.degree. C.

______________________________________Analysis: Calculated C : 60.18 H : 7.97 N : 1.56 Found 60.10 8.03 1.38______________________________________ IR spectrum (in solution in chloroform), strong band at 1265 cm.sup.-1.

EXAMPLE 7

9-Ethylthiocarbonyl midecamycine of Formula I in which R.sub.1 = C.sub.2 H.sub.5, X = S, R.sub.2 = H.

Operating as in Example 1, the methyl chloroformate was replaced with S-ethyl-thiochloroformate. After chromatography, 6 g of product was obtained which crystallised from petroleum ether, M.P. = 121.degree. C.

______________________________________Analysis: Calculated C : 58.58 H : 7.93 N : 1.55 S : 3.55 Found 59.00 8.04 1.43 3.57______________________________________ IR spectrum (on potassium bromide tablets), strong bands at 1130 and 1168 cm.sup.-1.

EXAMPLE 8

9-Propylthiocarbonyl midecamycine of Formula I in which R.sub.1 = C.sub.3 H.sub.7, X = S, R.sub.3 = H.

Operating as in Example 7, the S-ethyl-thiochloroformate was replaced with S-propyl-thiochloroformate. 8.2 g of a product was obtained which crystallised from petroleum ether, M.P. = 128.degree. C.

______________________________________Analysis: Calculated C : 59.00 H : 8.03 N : 1.52 S : 3.50Found 59.05 8.14 1.42 3.66______________________________________ IR spectrum (on potassium bromide tablet); strong bands at 1130 and 1168 cm.sup.-1.

EXAMPLE 9

9-Methoxycarbonyl tetrahydromidecamycine of Formula I in which R.sub.1 = CH.sub.3, X = O, R.sub.2 = H, saturated in 10,11 and 12,13.

Operating as in Example 1, tetrahydromidecamycine replaced the Midecamycine. 4.4 g of the desired product was obtained, M.P. = 86.degree. C.

______________________________________Analysis: Calculated C : 58.95 H : 8.40 N : 1.60Found 59.15 8.41 1.46______________________________________ IR spectrum (in solution in chloroform), strong band at 1280 cm.sup.-1.

EXAMPLE 10

9-Ethoxycarbonyl tetrahydromidecamycine of Formula I in which R.sub.1 = C.sub.2 H.sub.5, X = O, R.sub.2 = H, saturated in 10,11 and 12,13.

Operating as in Example 9, the methyl chloroformate was replaced with ethyl chloroformate. 4.3 g of the expected compound was obtained, M.P. = 82.degree. C.

______________________________________Analysis: Calculated C : 59.37 H : 8.50 N : 1.57Found 59.67 8.59 1.39______________________________________ IR spectrum (in solution in chloroform), strong band at 1275 cm.sup.-1.

EXAMPLE 11

9-Butoxycarbonyl tetrahydromidecamycine of Formula I, in which R.sub.1 = C.sub.4 H.sub.9, X = O, R.sub.2 = H, saturated in 10,11 and 12,13.

Operating as in Example 3, the Midecamycine was replaced with tetrahydromidecamycine. In the same manner, a yellow powder (6 g) was obtained, M.P. = 84.degree. C.

______________________________________Analysis: Calculated C : 60.17 H : 8.67 N : 1.53Found 60.58 8.63 1.47______________________________________ IR spectrum (in solution in chloroform), strong band at 1275 cm.sup.-1 .

EXAMPLE 12

9-Allyloxycarbonyl tetrahydromidecamycine of Formula I in which R.sub.1 = CH.sub.2 = CH -- CH.sub.2 --, X = O, R.sub.2 = H, saturated in 10,11 and 12,13.

Operating as in Example 11, the butyl chloroformate was replaced with allyl chloroformate. A yellowish powder (3.2 g) was obtained, M.P. = 93.degree. C.

______________________________________Analysis: Calculated C : 59.92 H : 8.38 N : 1.55Found 59.90 8.27 1.42______________________________________ IR spectrum (in solution in chloroform), strong band at 1268 cm.sup.-1.

EXAMPLE 13

9-Ethylthiocarbonyl tetrahydromidecamycine of Formula I in which R.sub.1 = C.sub.2 H.sub.5, X = S, R.sub.2 = H saturated in 10,11 and 12,13.

Operating as in Example 7, the Midecamycine was replaced with tetrahydromidecamycine. A yellowish powder (7.2 g) was obtained, M.P. = 96.degree. C.

______________________________________Analysis: Calculated C : 58.32 H : 8.34 N : 1.55 S : 3.54Found 58.37 8.14 1.49 3.37______________________________________ IR spectrum (in solution in chloroform), strong bands at 1135 and 1165 cm.sup.-1.

EXAMPLE 14

9-Ethoxycarbonyl-2'-acetyl midecamycine of Formula I in which R.sub.1 = C.sub.2 H.sub.5, X = O, ##STR5##

A mixture of 2.6 g of the compound of Example 2 and 3 g of acetic anhydride in 40 ml of pyridine was kept under reflux for 1 hour 30 minutes. Then 10 ml of methanol was added and reflux was continued for a further 15 minutes. The mixture was poured into 150 ml of water and rendered alkaline with dilute caustic soda solution to pH 8 to 9. The mixture was extracted twice with 100 ml of ethyl acetate and the organic phase was successively washed with 1 N hydrochloric acid solution, with saturated sodium bicarbonate solution, with water, dried over magnesium sulphate and the solvent evaporated under vacuum.

After filtration through an alumina column, the residue crystallised from an ether-hexane mixture. A lightly coloured solid (1.65 g) was obtained, M.P. = 239.degree. C.

______________________________________Analysis: Calculated C : 59.53 H : 7.93 N : 1.51Found 59.58 7.92 1.38______________________________________ IR spectrum (on potassium bromide tablets), strong bands at 1230 cm.sup.- (acetate) and 1260 cm.sup.-1 (carbonate).

The products according to to this invention have been studied as regards their pharmacological properties. In particular, their bacteriostatic action has been studied both "in vitro" and "in vivo" as well as the blood count results after oral administration.

"IN VITRO" BACTERIOSTATIC ACTION

This study was effected using Mueller-Hinton medium at pH 7 by the method using dilutions in frozen medium.

A series of half dilutions of the compounds to be studied was effected in order to obtain the contents of the medium of the culture of the active product ranging from 0.05 to 50 micrograms per ml. The media were seeded with gram.sup.+ microbial strains. After remaining in the oven at 37.degree. C. (24 to 48 hours), the minimal inhibitive concentrations or MICs were determined.

The results obtained with the products of this invention are set out in Table I below, in which also are given the results obtained with Midecamycine.

In Table II below, the results are given which were obtained with two of the compounds prepared, with a larger sample of gram.sup.+ bacteria.

"IN VIVO" ANTIBACTERIAL ACTION

The anti-streptococcal and anti-diplococcal activity was determined by the action of these products on septicaemia in mice. The mice were infected by intraperitoneal injection of a solution of a streptococcal or diplococcal pneumonia culture broth. Treatment orally took place twice a day for three days and began 1 hour after inoculation of the germs.

For each dose of the product, a group of 10 mice were used and the mortality of the mice of each group was comapred with that of an infected but non-treated control group. The observation was pursued for 6 days.

In Table III below, the results are given which were obtained with 1 of the products of this study, the compound of Example 2, in comparison with Midecamycine.

MEASUREMENT OF PLASMATIC RATES

A -- In Rats

The rats were divided into groups of four as homogeneous as possible and they had adminsitered to them per os a known quantity of the product in suspension in colloidal (gum) water by means of a gastric probe. As a function of time, one group of rats were killed each time and the blood of each rat was taken individually by way of the mesenteric vein. After addition of a quantity of heparine, the plasma was separated by centrifuging.

Starting with the plasma thus isolated, dosage of the product by a biological procedure was effected. Operation was effected by the diffusion method in Mueller-Hinton medium at pH 8 on a test germ, Sarcinea Lutea ATCC 9341. The dosage was effected in a cupula. The plasma was put into contact with the germ and on the next day the diameter of inhibition was measured, from which there was deduced the concentration with respect to a control sample ranging from) 0.25 to 8 .gamma./ml.

In Table IV below are indicated the plasmatic rates obtained from the compound of Example 2 as administered in doses of 100 and 200 mg/kg per os and by comparison the results obtained with midecamycine administered in the same doses.

B -- In Dogs

In the same manner, the plasmatic rates were determined which were obtained with dogs with a single dose of 400 mg of the compound of Example 2 administered orally. The results obtained are given in Table V in comparison with those obtained for an equal dose of Midecamycine.

The products of the invention can be utilised in medicine for the treatment of infections based on gram.sup.+ germs and in particular in the treatment of a staphylococcal and streptococcal infections.

They have been put up for administration orally (tablets, capsules, suspensions, oral gels etc.), by injection and by rectal administration.

By way of example, the following formulations can be indicated for the compound of Example 2.

______________________________________Capsules containing 200 mgCompound of Example 2 200 mgMagnesium stearate 5 mgfor a No. 1 capsuleTablets containing 200 mgCompound of Example 2 200 mgMicrocrystalline cellulose 100 mgAmberlite IRP 88* 20 mgMagnesium stearate 10 mgfor a 300 mg tablet(* ion exchange resin made by Rohm & Haas)Extemporaneous oral gelCompound of Example 2 0.1 gSodium saccharinate 0.0013 gSodium cyclamate 0.02 gGlycamil 0.002 gSodium carboxymethyl cellulose (300 CPS) 0.12 gAerosil 0.01 gGround sugar 4.1607 gMannitol 3.0 gAromatiser 0.586 g______________________________________ for an 8 g sachet for dilution with the contents of a teaspoonful of water. TABLE I__________________________________________________________________________ Anti-bacterial Activity "in vitro" in .mu.g/ml in solid__________________________________________________________________________medium diacyl Compound of Example No 14 8 2 g-ethoxy 3 1 4 7 propylBacterial sample Mideca- ethoxy carbonyl-2- Butoxy Methoxy Isobutoxy Ethylthio thioGram Positive Germs mycine carbonyl acetyl carbonyl carbonyl carbonyl carbonyl carboxyl__________________________________________________________________________Staphylococcus Londres 0,8 0,8 0,8 0,8 0,8 0,8 1,56 0,8Staphylococcus Aureus 521 IP 0,8 0,8 1,56 0,8 0,8 1,56 1,56 1,56Streptococcus Pyogenes 0,2 0,2 1,56 0,2 0,2 0,2 0,2 0,4GR. A 561 IPStreptococcus Agalactiae 0,4 0,4 0,8 0,8 0,4 0,4 0,8 1,56GR. B 55 118 IPStreptococcus Faecalis 0,4 0,4 0,8 0,8 0,4 0,4 0,8 0,8GR. D A 23Sarcina Lutea ATCC 9 341 0,8 0,8 1,56 1,56 0,8 1,56 1,56 1,56Bacillus Cereus ATCC 9 634 0,4 0,4 0,8 0,8 0,4 0,8 0,8 1,56Bacillus Subtilis ATCC 6 633 0,8 0,8 0,8 1,56 0,8 0,8 0,8 1,56Listeria Monocytogenes 5 734 0,8 0,8 0,8 1,56 0,8 1,56 1,56 1,56Corynebacterium Abbott 0,4 0,2 0,4 0,4 0,2 0,4 0,4 0,8 Compound of Example No.Bacterial sampleGram Positive Germs 9 5 6 10 11 13 12__________________________________________________________________________Staphylococcus Londres 1,56 0,8 0,8 1,56 3,12 3,12 1,56Staphylococcus Aureus 521 IP 3,12 1,56 1,56 3,12 6,2 3,12 3,12Streptococcus Pyogenes 0,4 0,2 0,2 0,8 0,8 0,8 0,4GR. A 561 IPStreptococcus Agalactiae 1,56 0,8 0,8 1,56 3,12 3,12 1,56GR. B 55 118 IPStreptococcus Faecalis 0,8 0,4 0,8 1,56 3,12 3,12 3,12GR. D A 23Sarcina Lutea ATCC 9 341 3,12 1,56 1,56 3,12 3,12 3,12 3,12Bacillus Cereus ATCC 9 634 1,56 0,8 0,8 1,56 3,12 3,12 1,56Bacillus Subtilis ATCC 6 633 1,56 0,8 0,8 1,56 3,12 3,12 1,56Listeria Monocytogenes 5 734 1,56 0,8 0,8 1,56 3,12 3,12 3,12Corynebacterium Abbott 0,8 0,4 0,4 0,8 1,56 1,56 1,56__________________________________________________________________________ TABLE II__________________________________________________________________________ M.I.C. .mu.g / ml Composition Composition of Example 1 of ExampleGERMS Midecamycine mono 14 di__________________________________________________________________________Staphylococcus Londres 0,4 0,4 0,4Staphylococcus 209 IP 0,4 0,4 0,4Staphylococcus Aureus Gervais D 319 0,8 0,8 0,8Staphylococcus Aureus E 120 0,8 0,8 1,56Staphylococcus Albus P C I J 200 0,8 0,8 1,56Streptococcus Pyogenes gr A 561 IP 0,2 0,2 0,4Streptococcus Pyogenes gr A D 313 0,2 0,2 0,2Streptococcus Agalactiae gr B 0,4 0,4 0,4Streptococcus Pyogenes gr C 1,56 1,56 1,56Streptococcus Faecalis var. Zymogenes 1,56 0,8 0,8Streptococcus Faecalis gr D 5 434 IP 0,4 0,4 0,4Streptococcus Faecalis gr D F 262 1,56 1,56 1,56Sarcina Lutea ATCC 9341 0,1 0,1 0,1Listeria Monocytogenes 5 844 IP 0,8 0,8 0,8Listeria Monocytogenes Ramisse type IV 1,56 1,56 1,56Listeria Monocytogenes Joubert E 102 0,8 0,8 0,8Erysipelothrix Insidiosa E 159 0,8 0,8 0,8Erysipelothrix Insidiosa A 27 0,8 0,8 0,8Bacillus Cereus ATCC 10 702 0,4 0,4 0,8Bacillus Cereus ATCC 9 634 0,4 0,4 0,8Bacillus Subtilis Leugar A 156 0,4 0,4 0,8__________________________________________________________________________ TABLE III______________________________________ Dose P. 100 of survival at 6th dayProduct mg/kg .times. 6 j. Diplococcus Streptococcus______________________________________Control 0 0 0Composition of 200 50 70Example 2 400 100 100Midecamycine 200 20 40 400 80 100______________________________________ TABLE IV__________________________________________________________________________ Dose administered 100 mg / kg Dose administered 200 mg / kgTime of Composition of Composition ofTreatment Example 2 Midecamycine Example 2 Midecamycine(in minutes) (.mu.g/ml) (.mu.g/ml) (.mu.g/ml) (.mu.g/ml)__________________________________________________________________________ 30 1,61 0,39 9,43 2,45120 4,52 2,43 9,57 6,82180 3,8 1,87 7,27 8,23240 1,88 1,4 7,6 5,54300 1,29 1 3,4 4,2420 0,54 0,26 -- --__________________________________________________________________________ TABLE V______________________________________Plasmatic rate in dogsSingle dose of 400 mg per osTime ofTreatmentafter Concentration in .mu.g/ ml plasmaadministration Composition of example 2 Midecamycine______________________________________ 30 minutes 3,4 0,96 60 minutes 2,84 3,2 90 minutes 2,22 2,46120 minutes 1,46 1,34180 minutes 0,84 1,1240 minutes 0,6 0,78300 minutes 0,46 0,46420 minutes 0,23 0,18______________________________________

Claims

1. Compounds represented by the formula: ##STR6## in which X is selected from the class of oxygen and sulphur,

R.sub.1 is selected from the group consisting of alkyl of 1 to 5 carbons, isobutyl, allyl and phenyl, the broken lines indicating the optional presence of double bonds with the proviso that the two double bonds in the 10, 11 position on the one hand and 12, 13 on the other, exist simultaneously or neither of them exists.

2. The compound according to claim 1 wherein said compound is 9-methoxycarbonyl midecamycine.

3. The compound according to claim 1 wherein said compound is 9-ethoxycarbonyl midecamycine.

4. The compound according to claim 1 wherein said compound is 9-butoxycarbonyl midecamycine.

5. The compound according to claim 1 wherein said compound is 9-isobutoxycarbonyl midecamycine.

6. The compound according to claim 1 wherein said compound is 9-phenoxycarbonyl midecamycine.

7. The compound according to claim 1 wherein said compound is 9-allyloxycarbonyl midecamycine.

8. The compound according to claim 1 wherein said compound is 9-ethylthiocarbonyl midecamycine.

9. The compound according to claim 1 wherein said compound is 9-propylthiocarbonyl midecamycine.

10. The compound according to claim 1 wherein said compound is 9-methoxycarbonyl tetrahydromidecamycine.

11. The compound according to claim 1 wherein said compound is 9-ethoxycarbonyl tetrahydromidecamycine.

12. The compound according to claim 1 wherein said compound is 9-butoxycarbonyl tetrahydromidecamycine.

13. The compound according to claim 1 wherein said compound is 9-allyloxycarbonyl tetrahydromidecamycine.

14. The compound according to claim 1 wherein said compound is 9-ethylthiocarbonyl tetrahydromidecamycine.

15. An antibiotic medicament comprising, as its active ingredient, an antiobiotic effective concentration of the compound represented by the formula: ##STR7## in which X is selected from the class of oxygen and sulphur. R.sup.1 is selected from the group consisting of alkyl of 1 to 5 carbons, isobutyl, allyl and phenyl and R.sub.2 is selected from the group consisting of hydrogen and acetyl, the broken lines indicating the optional presence of double bonds with the proviso that the two double bonds, in the 10, 11 position on the one hand and 12, 13 on the other, exist simultaneously or neither of them exists.

16. A antibiotically composition which contains the compound of claim 1 as an active ingredient, in a pharmaceutically effective concentration associated with a pharmaceutical vehicle for oral, rectal or parenteral administration.

17. The process which comprises reacting a midecamycine compound selected from the class consisting of midecamycine or tetrahydromidecamycine with a chloroformate or thiochloroformate of the formula: ##STR8## in which X is selected from the class consisting of oxygen and sulphur and R.sub.1 is selected from the class consisting of alkyl of 1 to 5 carbons, isobutyl, allyl and phenyl in pyridine and further reacting the resultant product with acetic anhydride in pyrindine to obtain a product of the following structure: ##STR9## wherein R.sub.2 is acetyl.