1030 Journal of Medicinal Chemistry, 1974, Vol. 17, No 9 ( 5 ) R. J. Langenbach, P. V. Danenberg, and C . Heidelberger, Biochem. Biophvs. Res. Commun., 48, 1565 (1972). (6) P. V. Danenberg, R. J. Langenbach, and C. Heidelberger,
Scheme I. Prominent Mass Spectral Fragment Ions of 6’-Amino-6’-deoxygentamicin A (6)
Biochemistry, 13,926 (1974). (7) J. L. Aull, J. A . Lyon. and R. B. Dunlap. Microchem. J . . 19. 210 (1974). (8) M. Yoshikawa, T. Kato, and T. Takenishi, Tetrahedron
Lett., 5065 (1967). (9) M. Yoshikawa, T. Kato, and T. Takenishi, Bull. Chem. Soc. J a p . . 42,3505 (1969).
OH
HO
I
OH m e 146 Synthesis a n d Biological Properties of
6‘-Amino-6’-deoxygentamicin A Tattanahalh L Nagabhushan* and Peter J L. Daniels Schering Corporation, Bloomfield AVeccJerse> 07003 ReceiLed Februarq 21. 1974 Structure-activity relationship studies on aminoglycoside antibiotics possessing a paromamine moiety have shown t h a t replacement of the 6’ primary hydroxyl group by a n amino group leads to compounds with enhanced antibacterial properties. For example, neamine (1) is biologically more active than paromamine (2)l a n d kanamycin B (3) is more potent than kanamycin C (4).2 It was of interest, therefore, to convert the relatively weakly active gentamicin A (5)3 t o its 6’-amino-6’-deoxy derivative 6 to examine its biological properties.
HC=O
I +
%HA
HO R = H, m / e 191 R = gentosaminyl, m/e 336 R = 2,6-diamino-2,6-dideoxyD-glUcOSy1, m / e 351 k c 0
/-H,O ,
R = H, m / e 173 R = gentosaminyl, m / e 318
I
SH 111 c,
101
R = H, m / e 163 R = gentosaminyl, m / e 308 R = 2,6-diamino-2,6-dideoxy. D-glucosyl, m / e 323 -40
1
R = H, m / e 145 R = gentosaminyl, m / e 290 R = 2,6-diamino-2,6-dideoxyD-glucosyl, m / e 305
6 2.5 ppm as a sharp singlet and the two anomeric signals at 6 5.33 and 5.05 ppm, each with a coupling constant of 3.5 Hz. T h e low-field signal is assigned to H-1’ and the doublet a t 6 5.05 ppm to H-1’’ by analogy with the assign-
ments made by Lemieux a n d coworkers5 for structurally closely related kanamycin B. Furthermore, the pmr specOH trum of gentamicin A (5) was similar to t h a t of 6 and exhibited two doublets a t 6 5.22 and 5.02 ppm with coupling R H.N O WNH, constants of 3.5 and 3.75 Hz, respectively. T h e doublet a t L R = NH,; R’ = H 6 5.22 ppm was attributed to H-1’ by the INDOR response 2. R = 0H;’R’= H of the H-2’ resonances (quartet a t 6 2.75 ppm in the nor3, R = NH,; R‘ = 3-amino-3-deoxy-a-D-glucopyranosyl mal spectrum, 5 2 , , 3 . = 9.0 Hz) obtained by monitoring 4. R = OH; R’ = 3-amino-3-deoxy-a-D-glucopyranosyl the left-hand peak of the anomeric doublet centered a t 6 5. R = OH; R’ = 3-methylamino-3-deoxy-a-D-xylopyranosyl 5.22 ppm. Similarly, the doublet a t b 5.02 ppm could be 6 R = NH,; R’ = 3-methylamino-3-deoxy-a-~-xylopyranosyl assigned t o H-1” (quartet at 6 3.60 ppm for H-2”, J P . ~ , = 9.0 Hz in the normal spectrum). T h e synthesis of 6‘-amino-6’-deoxygentamicin A (6) was T h e biological properties of gentamicin A ( 5 ) have been accomplished by standard procedures a s follows. Gentamr e p ~ r t e d .Although ~ both 5 and its 6’-amino-6’-deoxy conicin A (5) was converted to tetra-N-benzyloxycarbonylgengener 6 have some broad spectrum activity, neither has tamicin A (7)a n d then to t h e corresponding penta-0-acepotent inhibitory activity us. Escherichia coli, Klebsiella tyl-6’-0-triphenylmethyl derivative 8 in a overall yield of pneurnoniae, or Pseudomonas aeruginosa. In particular, 73%. The triphenylmethyl group was removed with acid neither compound has activity against strains carrying and the p-toluenesulfonyl group introduced to give pentagentamicin adenylylating or acetylating R factors or ~-acetyltetra-N-benzyloxycarbonyl-6’-0-p-toluenesulfonyl-against strains carrying kanamycin phosphorylating R facgentamicin A (9) in 91% yield. The p-toluenesulfonyl tors. However, as shown in Table I, the in i i t r o biogroup was displaced by azide ion in near quantitative logical activity of 6 against some sensitive strain is superiyield and the resulting compound 10 subjected to O-deacor to t h a t of 5 , gentamicin C complex (Garamycin): a n d etylation (70% yield) followed by catalytic hydrogenation the structurally related kanamycin B. The most strikto give crude 6’-amino-6’-deoxygentamicinA (6). T h e ing property of 6 is its potent in vitro inhibitory activity compound thus obtained was purified by column chromaagainst Staphylococcus aureus and Streptococcus p y tography on silica gel using chloroform-methanol-ammoogenes. nium hydroxide (3:4:2) as the developing phase (40% Experimental Section yield) followed by rechromatography on Dowex 1-X2 in the hydroxyl cycle using water as the eluent to provide an Thin-layer chromatography was performed on silica gel GF analytically pure sample in 21% yield. T h e structure of 6 (Analtech, Inc., Newark, Del.) using chloroform-methanol-ammonium hydroxide (3:4:2) as the developing phase. Column chrowas established as follows. matography was carried out on silica gel (60-200 mesh, J. T. Elemental analysis of 6 was consistent with the formula Baker Chemical Co., Phillipsburg, N. J.) using the same solvent C I ~ H ~ ~ N ~ O ~ C and H t~h O e mass H spectrum showed the system and on Dowex 1-X2 (200-400 mesh, hydroxide form, ( M H ) + ion a t rn/e 468 in agreement with t h e composiSigma Chemical Co., St. Louis, Mo.) with water as the eluent. tion. Prominent fragment ions in the mass spectrum4 are The pmr spectra were recorded using a Varian Associates XLshown in Scheme I. 100 nmr spectrometer. Chemical shifts are given in 6 values for solution in deuterium oxide using DSS as the internal standard. T h e pmr spectrum of 6 showed t h e N-methyl protons a t
H2NwF
Journal of Medicinal Chemistry, 1974, Vol. 17, No, 9 1031
Notes
Table I. I n Vitro Antibacterial Activity of 6'-Amino-6'-deoxygentamicinA (6), Gentamicin A (5), Gentamicin. and Kanamvcin B
Test organism Staph. aureus 209P Staph. aureus 59N Strept. C Strept. 27 Strept. group A cruz Strept. Alvarez Bacillus subtilis 6623 Proteus mira bil is Harding Salmonella Gr. B. typhim
Minimum inhibitory concn, Pgcg/mla GentaKana5 6 micin mycin B 3.0 37.5 >50 >50 >50 >50 0.8
0.03 0.8 0.8 0.8 0.8 0.03 0.01
0.1 0.1 3-7.5
3-7.5 3.0 3.0 25 7.5 17.5 >25
