I
COOH
I
COOH I1
COOH 1v
+
111 (RCO),O a,R=Et
kOOH
-
I11
pyridine
b,R=Pr c, R = i-Pr d, R = cyc10-B~ oxidation
and
isomerization
m-CPBA
,
COOH
The conversion of these A2 esters, which >ire biologically less active, to the more potent Ad compounds VI1 was accomplished by utilizing the oxidative-reductive process for isomerization of the double bond discovered recently in these laboratories, The isomerizatiori was accomplished by oxidation of J’ with 1 equiv of 111chloroperbenzoic acid in CHCls. In this process the heterocyclic sulfide group is oxidized to the sulfoxide, arid the double bond isomerizes to the A s position. The final problem mas the removal of 0 from S. A1though some difficulties in this type of reduction had been reported,S an elegant method for the reduction of cephalosporin sulfoxides was discovered by Kaiser, et al.’ Applying this method, we readily reduced the sulfoxides V I with SriClz arid a c C l in DhIF and isolated the desired Ad derivatives VI1 in good yields. All compouiids were identified and characterized by clemental analyses, uv, ir, nmr spectroscopy, tlc, arid by bioautography where applicable (see Tables I and 11). I’reliminary i,i vitro antibiotic activities of the,:.e compounds against a variety of Gram-positive and Gramnegative bacteria are reported in Table 111. For comparison, the activities of sodium cephalothin are included. These new esters VI1 have essentially broad-spectrum antibiotic activity and they are slightly more active than sodium cephalothin. The butyrate (VII, b) arid isobutyrate (VII, e) displayed the highest activities. Compounds V aiid TI were markedly less active. The more potent compounds VI1 in the iil uiti.0 tests were chosen for in vivo assay. Groups of S white mice were inoculated with Sti*eptococcus pyogeiies C203 and then given oral doses of antibiotic 1 and 5 hr after inoculation with the bacterium. Table I11 also shows that EDbovalues of the new derivatives are slightly better than that of sodium cephalothin. Thus, the results of in vitro and i72 vivo tests showed that introduction of a sterically more hindered ester function in the 3 position retains good antibiotic activity. A study of enzymatic hydrolysk is in progress arid will be reported later.
V
Experimental Section
I
COOH VI
COOH VI1
Esterification of the 3-CH20H in I11 was carried out by treatment with the appropriate aliphatic acid anhydride in pyridine according to the reported procedure,jS6 and the esters V were isolated in good yield. (6) R . B. Koodward, K. Heusler, J . Gosteli, P. Naegeli, W. Oppolzer, R . Ramage, R. Ranganthan, and H. Vorbrugyen. J . Amer. Chem. Soc., 88, 852 (1966).
Melting points were determined on a hlel-Temp apparatus and were uncorrected. Nmr spect,ra were obtained on a Varian Associates Model HA-60 spectrometer. Uv spectra were det’ermined 011 a Gary hIodell4 recording spectrometer. Tlc behavior was followed using silica gel plastic sheets with fluorescent indicator (Eastman). The solvent syst,em was AcOH-CHC13 (15: 85). Bioautographs were performed according to techniques described by Jeffery, et uL8 3-Hydroxymethyl-7- [2-(thienyl)acetamido]-2-cephem-4-carboxylic Acid (III).-Following t,he procedure of Cocker, et ul.,: 3-acetoxyme thyl-i- [2-(thienyl)acetamido]-2-cephem-4-carboxylic acid6 (30 g, 0.075 mole) was hydrolysed in a mixture of 25 nil of Me&O and 250 ml of HI0 with 1 X KaOH (150 ml). The soln was kept a t 39” overnight. After cooling and acidificatioii to pH 2 wit,h 2 9 HC1, it was extract,ed with EtOAc. After the extract was washed and dried (blgS04),the solvent was coiicd t o a small vol (ca. 100 ml). The pptd hydroxy acid was filtered and dried to give 14.5 g (55%); mp 145-146’ dec; Rr 0.145; Xmsx 232 mp ( e 15, 700) in HzO; ymax5.67 (lactam C=O), 5.76 (COOH), 6.05, and 6.56 p (COXHI); apparent molecular weight of 360 (calcd 354.4); nmr (DzO-?r’aHCOB)peaks a t T 6.18 (side(7) J. A . Webber, E. M. Van Heyningen, and R. T. Vasileff, zbid., 91, 5674 (1869). (8) J. D’A. Jeffery, E. P. Abraham, and G. G . F. Xeuton, Baochrm. J . 81, 591 (1961).
.\
\'I1
T.\BLI.
I11
Hllll>oc;ll~.\1, :IYrlvl
r--Gritrii-neg&tive
Cornpi1
Shiyrlla ' p . (S-9)
d i
(5-26)
r1I.>"
urpaniarns (MI(: #pi nil!Klebsiella s p . (I;-26)
derotariii sp. (9-68)
-.. - -- t'enicdkiil renratant', SlaphylycuccuP a u r e u a iV-:30) iv-32 )
.
-
-
I.:Ihd
lieHin@ (V-84)
.\ssayc
trig
kc
X 2
__
Sodium cephalothiii 12. S 13.4 4.0 (;.2 (I..?; 1 . 0 O . ~ i ;1.0 0.4: 0.li 1000 2ti.7 VIIa 6.7 9.4 .) Y.l I)..-); 1.0 I)..?; 1.0 0.4: 1.0 1130 23..-1 VIIh .,i '3 0. t j 6.4 7.5 0.4;l.O 0.4;l.il 1240 2:E.ti tl.2:l.O VII 14.h lh.O 12.3 12.8 I)..?; 1.0 0 . 3 ; ].(I IJ.4; 1.0 1240 "3.6 VIId 8.S 11.q 2 .5 12.5 0,4;1.0 0.5;l.l~ O.l;l,(J 11% 24.1 C:. IV. Godzeski, G. Brier, and 1).E. Pavey, A p p l . Microbial., 11, 122 (1963). The interpretation of these results should be doni, O I I a comparative basis only and requires use of an int,ernal standard. b The minimum inhibitory t7oIicentrations in rg/Inl; the fi value is without,, the second with human serum. c The results are reported as pg/ nil of Pl'a cephalothin activity against, Bacillzcs subti W. S. Boniece, W. E. Wick, I). H. Holmes, arid C. E. Redman, J . Bacterial., 84, 1242 (1962). Drug administered orally to mice, I and 5 hr post inject,ioii. 1 ) .
