CLIXDAMYCIN
concluded that this compound, 4b, was the C-7 epimer of 4a. Treatment of lincomycin.HC1 (la) or epilincomycin.HC1 (lb) with SOClz in CCl, resulted in a highly stereospecific reaction. If more than one 7-C1 product was formed during the reaction, the amount was too small to be detected by tlc in solvent systems which easily separate the epimers. An alternate method for the preparation of 4a involved the use of triphenylphosphine dichloride. The halogenation of alcohols with triphenylphosphite methiodide and related compoundsg is known to proceed with inversion of configuration except when anchimerically assisted by a neighboring group.'O Similar results were obtained when these reagents were used to halogenate various carbohydrates.ll The related triphenylphosphine dihalides are also reported to halogenate optically active alcohols with net inversion of configuration.12 When lincomycin. HC,l (la) was treated with triphenylphosphine dichloride, a monochlorinated product was isolated which was identical with 4a. This result implied that chlorination of l a by SOC1, occurred with inversion of configuration. A third route to the preparation of 4a involved the use of triphenylphosphine and CCl,, a procedure which is also known to chlorinate alcohols with inversion of configuration.'3 The product obtained when l a was chlorinated by this method was identical with 4a. This result strengthened our belief that chlorination of lincomycin. HCl (la), under the conditions described, occurred with inversion of configuration a t C-7. Support for this hypothesis was obtained by chemical degradation. Another paper in this series describes the cleavage of l a into two major components, 4'-n-propylhygric acid (6) and methyl a-thiolincosaminide (7) (MTL).I4 Magerlein and Kagan have chlorinated 7 via the triphenylphosphine-carbon tetrachloride procedure to yield 7-chloro-SITL (8) which upon coupling with 6 gave material identical with 4a.I5 These authors described chemical evidence which strongly suggested the 7(S)-Cl configuration for 4a and 8. Unequivocal evidence defining the configuration of the C1 substituent in 4a and 8 was obtained by conversion of 8 into the dimethylmercaptal 9, followed by oxidation of this material with periodate-permanganate.I6 ,4n acidic fragment. isolated from this reaction was identified as L-chloropropionic acid (10). A comparison of its optical rotation with those reported in the literature for D- and L-chloropropionic acid as well as wit'h that of an authentic sample of L-chloropropionic acid prepared from L-alanine led to the assignment of the L configurat'ion for 10. Since the configuration of the OH a t C-7 in l a is known to be D or 7 ( R ) ,it follows that chlorination of l a by any of the three methods (9) (a) S. R. Landauer and H. S . Rydon, J . Chem. Soc., 2224 (1953): (b) D. G . Coe. S.R . Landauer, and H. N. Rydon, ibid.. 2281 (1954); H. K. Rydon and E. L. Tonge, ibid., 3043 (1956). (10) J. P. Sohaefer a n d D. 5. Weinberg, J . Org. Chem., SO, 2635, 2639 (1965). (11) K. K . Kochetkov and A . I. Usov, Tetrahedron, 19, 973 (1963). (12) (a) G. A. Wiley, R. I,. Hershkowitz, R. B. Rein, and B. C. Chuny, .I. A m e r . C h e m . Soc., 86, 964 (1964): G. A. Wiley, B. J. Rein, and R . L. Hershkowitz, Tetrahedron Lett., 36, 2509 (1964). (13) (a) J. B. Lee and I. M. Downie, Tetrahedron, 23, 359 (1967); (11) 11. Brett, I. XI. Downie, and J . R. Lee, . I . O r g . Chem., 32, 855 (1967). (14) TV. Schroeder, 13. Bannister, and 11. Hoeksenia. J . A m e r . C h e m . Soc., 89, 2448 (1967). ( 1 5 ) B. J. Maeerlein and F. IZaaan, J . X e d . C h e m . , 1 2 , 780 (1969). (16) R . V. Lemieux and E. vonRudloff, C a n . J . Chem., 33, 1711 (1955).
SCHEME I
OH l a , R1=OH;R,=H
Ib, R, = H; R, = OH CH,
I
CH
+
OH 2a, X = S=O 2b. X = CH,-C-CH, 2c, X = C=O CH i
I
O=S OH
'
3
\
I
HC-CI
CH3
I
I
RI-T-RI CONH-CH
OH 4a, R, =H; RL= CI 4b, R,= CI: R2 = H 4c, R, = H: R2= Br 4d. R1= H & = I
Jorirnal o j Jlcdicinal Chemistry, 1.970, Vol. 13, .\o.
C L I li v.\h.1Y c I s
4
619
TABLE: I ANTlBhCTERIhL
Standard cur\.e assay
Compd
--------
AkCTIVITIFBO F i-HALO-7-DEOXYLINCOMYCIN
HYDROCHLORIDES
Serial dilution minimal inhibitory concentration*------
Stapkyl-
with Sarcina lutea
aureus
.\TCC Y3iln
OSU 284
1 0.5
0.4 0.8 0.1 0.4 0.0,; 0.05
CUCCUE
Staphylococcus aureus UC 552c
Streptococcus faecalis UC 3235
Escherichia coli .iTCC 26
Proteus idgaris ATCC 8427
Salmonella schottmeulleri
ATCC 9149
IIouse protection aasagd Staphylococcus aureua Sub-
cutaneous
Oral
0.8 12.5 400 so0 4000 1.0 1.0 lb 1. G 23.0 > 200 > 200 >200 0.4 0,s 4a 4 0.1 6.2 2.5 250 64 1. 0 1.3 4b 2 0.8 12.3 >200 >200 >200 0.4 0.5 4c 4 0.0.5 6.2 100 100 50 0 .9 1. 3 4d 44.5 0.05 3.2 12.5 50 50 Determinations made in L. J. Hanka, D. J. Mason, &I. R. Burch, and R. W. Treick, Antimicrob. 9 8 . Chemother., 565 (1962). Brain Heart Infusion medium (Difco). Inocula consisted of about 105 organisms/ml of medium. Twofold dilutions of the antibiotic were used in each sensitivity determination. Endpoints were read a t 20 hr and are expressed in minimal inhibitory concentration of Method compound in micrograms per millilit,er. c Organism resistant t o penicillin, streptomycin, tetracycline, and erythromycin. of C. Lewis, H. W. Clapp, and J. E. Grady, Antimicrob. Ag. Chemother., 570 (1962). 1a
4a; [ a ] +214' ~ (CHC13). Anal. (CI8H3&1N20jS) C, H, C1, N , s. Clindamycin (4a) via (C&)3PC12 Route. Second Procedure. -To a solutioii of 26.3 g of ( C & ~ ) Z P in 400 ml of ?rleCN was added 7.09 g of C1, keeping the temp at, about 30" by cooling. Liiicomycin (4.06 g ) \vas added. After stirring at 25' for 3 hr, 100 ml of ?*leOII was added and the soliition coricd to dryness under vacu\im. The residue was partitioiled between EttO and H20. The H2O phase was made basic with 2 3' NaOH aolrition and extracted with CHC1, and the extract concd to dryness iinder vaciiiim. The residue was chroniatographed over silica gel using CHC13-MeOH (9: 1) for elution. The major fraction contained 3.1 g of the free base (73% yield) which was converted into the HC1 salt and crystallized from EtOH-EtOAc t o give material identical with 4a prepared by the SOC12 procedure. Clindamycin (4a) cia (C6Ho)rPCC1,Route. Third Procedure.Aisolutio11 of 50 g of lincomycin.HC1 ( l a ) , 120 g of (C6Hj)J', mid 500 ml of hIeCS v a s cooled at, 20" and 500 ml of CC1, was added. stirring at 25" for 18 hr the reaction was concd to dryness under vacuum. The residue \vas shakeii with 200 ml of HZ0 for 2 hr and filtered and the solid, (C6H;)rPO, was discarded. The filtrate was adjusted to p H 11 with G S NaOH sohition and estracted with CHCL. The extracts were concd to dryness iiiider vacuuni, the residile dissolved ill 200 ml of MeOH and heated at, reflux for 1 hr. The 3IeOH was distd under vacuum and 100 ml of HtO and 10 ml of 3 7 5 HC1 were added t o the residue. A4fter shaking for 1 hr the mixture was filtered and the solid material discarded [more (C&)3PO]. The filtrate was extracted with CC1, and the extracts discarded. The H t 0 phase was adjusted to pH 11 with 6 S S a O H solution and extracted with CHC13. The extract was concd t o dryness under vaciiuni, the residue converted into the HC1 salt and crystallized from EtOH-EtOAc to give 35 g, ( G i % ) , of material identical w i t h l a prepared by the SOClt and (C6Ha)rPCl procedures. 7(H)-Chloro-7-deoxylincomycin Hydrochloride (4b).-Epilincomycin.HC1 ( l b ) vas chlorinated via the SOCL procedure to ~ (Hzo), mp 164-166". give a 29% yield of 4b; [ a ] f122" Anal. (CI,H~,CIJV,O~S) C, H, C1, Ii,S. 7-Bromo-7-deoxylincomycin Hydrochloride (4c).-Lincomy-
cin' HC1 was brominated by substituting (C6H6)&'Br2 for (C6H6)3PC12 in the second procedure described for the prepara~ ( H z ~ )mp , 137tion of 4a. A 307, yield of 4c [ a ] +130" 139" was obtained. Anal. (C18Ha4C1BrN20jS) C, H, C1, Br, N, S. By slibstituting CBr, for CCl, in the third procedure described for the preparation of 4a, a 3 6 s yield of product was obtained. This niaterial was identical with 4c obtained via the (CsH:)3Ph;! procedure. 7-Iodo-7-deoxylincomycin Hydrochloride (Id).-By substitiiting CIa for CClr in the third procedure described for the preparation of 4a, a 0.5Yc yield of 4d was obtained. Although no elemental analytical data were obtained for this compound, its behavior upon tlc and the nmr spectrum and mass spectrum fragmentation pat.terns were consistent with the proposed structure. Dimethyl Mercaptal of 7(S)-Chloro-7-deoxy-~-methylthiolincosaminide (9).-A mixtvre of 71 g of 7-chloro-3ITL (7), 750 ml of 3iYG HC1, and 350 g of MeSH was stirred at 0" for 6 hr. H20 ( 2 1.) was added and the reaction extracted well with Skellysolve B. The H 2 0 phase was adjusted to pH 11 by the addition of KOH pellets. A ppt formed which was collected, dried, and recrystd from MeOH to give 62 g (73Yc)of 9; mp 122-124", [ a ] D +a0 (DMF). Anal. (CloHt&1N04S) C, H, C1, X ; S: calcd 20.05; found, 19.53. L-a-Chloropropionic Acid (lo).-To a soliition of 300 g of SaIO,, 32 g of KIISOr, and 21 g of K2C03dissolved in 1 1. of HtO and stirred at 25' was added 16.8 g of 9. .4dditional K2C03was added as necessary to keep the reaction a t pH 7 to 7.5. After 18 hr the reaction was adjiisted to pH 3 by the addition of concd H2S04 and then extracted with EttO. The extracts were concd under vacuum and the residue distd through a 15-cm Vigreux column. Two grams (35%) of product, 10 [bp 9@91" (15 mm), [ a ] -18" ~ (neat); reported -18.2" (neat)l*]was obtained. I n a l . (C3H:CClO) C, H, C1. Alcoholysis of 2a, 3, and &-Treatmelit of Za, 3, and 5 with aq base or hot MeOH resulted in the quantitative removal of the sulfite functions and regeneration of the alcohol.
Acknowledgments.-The aut'hors are indebted to L>. J. hfasori and C. Lewis for the antibacterial assays.
