Journal of Medicinal Chemistry @ Copuright 1964 by the American Chemical Society
VaLunm 7, XUMBER 1
JANUARY 8, 1964
Syntheses of 5-Trifluoromethyluracil and 5-Trifl~oromethyl-2’-deoxyuridine~~~ CHARLES HEIDELBERGER,3DAVIDG.
PARSONS, AND
DAVID c. REMY
Mcdrdle Memorcal Laboratory, I.nzversity o j Wzsconszn, Illadzson 6 , Thconszn Receiued September 12, 1963 5Trifluoromethyluracil has been synthesized starting with trifluoroacetone, which was converted into the cyanohydrin and then into the cyanohydrin acetate, which was pyrolyzed t o trifluoroacr)-lonitrile. To the latter was added hydrogen bromide in methanol, and P-bromo-a-trifluoromethylpropionamide was obtained, which w m condensed with urea or N-acetylurea to give a-trifluoromethj-1-8-ureido propionamide or its acetyl derivative. The ureidoamides were cyclized to 5-trifluoromethyl-5,6-dihydrouracil by refluxing in hydrochloric acid. Bromination and dehydrohalogenation of the dihydropyrimidine gave 5-trifluoroniethyluracil, which was converted enzymatically into 5-trifluoromethyl-2’-deoxpridine. The latter compound is incorporated into DSA, is mutagenic t o bacteriophage, inhibits (in the nucleotide form) the enzyme, thymidylate synthetase, and is a potent inhibitor of the growth of Adenocarcinoma 755 in mice. 5-Trifluoromethyluracil under mild alkaline conditions is quantitatively converted into 5-carboxyuracil and was condensed with glycine and glycj-lglpcine to give 5-uracoylglycine and 5-uracoylglycylglycine.
human cancers.loa,b I n view of these interesting biochemical and therapeutic properties, it’ appeared desirable to determine whether additional fluorinated pyrimidine antimetabolites might be designed and prepared that would have similarly interesting properties. It has previously been shown that 5-bromouracil and 5-iodouracil are incorporated into D S A in microorganisms, and that 5-bromo-2’-deoxyuridine and 5-iodo-2’-deoxyuridine are similarly incorporated into DSA in mammalian cells.*1c This incorporation, which often has consequences of conferring up011 the cells increased mutabilityl2&and radiosensitization, 1*h is doubtless made possible by t’he fact that the bromo and iodo atoms are about the same size as the met’hyl group in thymine, and these compounds do replace thymine in the D3-A. It seemed likely to us that replacement of the methyl group in thymine by a trifluoromethyl group would lead to a fluorinated pyrimidine 5-trifluoromethyluracil (XI), that also might be incorporated into DXA, although the trifluoroniethyl group is somewhat larger (van der Waals radius 2.44 K.) than the methyl group (2.00 Ai.). Accordingly, attsmpts were made to synthesize this compound. A number of unsuccessful syntheses by a variety of routes were attempted, but the det,ails will not be described here. During the course of this work the
Based upon the observation by Rutman, et a1.,4 that uracil-was utilized to a greater extent for nucleic acid biosynthesis in tumors than in corresponding normal tissues, a new antimetabolite, 5-fluorouracil, was designed and synthesized,sa h This compound turned out to have considerable tumor-inhibitory activity against mouse and human tumors6a,hand is detoxified to a lesser extent by tumors than by most normal tissues in mouse and nian.7ah,CThe compound is incorporated into RSA,* but exerts its tumor-inhibitory activity as a result of metabolic conversion into 5-fluoro-2’-deoxyuridine j’-monophosphate, which is a potent inhibitor of the enzyme, thymidylate synt hetase. 9a b The nucleoside 5-fluoro-2‘-deoxyuridine is more effective than 5-fluorouracil against mouse and (1) This work was supported i n part by grants, C-2832 and CRTY-5002, from the Yational Cancer Institute, National Institutes of Health, U. S. Public Health Service. (2) A preliminary account of this work appeared: C. Heidelherger, D. Parsons, and D. C. Remy, J . A m . Chem. Soc., 84, 3597 (1962). (3) American Cancer Society Professor of Oncology. (4) R. J. R u t m a n , A. Cantarow, and K. E. Paschkis, Cancer Res., 14, 116 (1954). ( 5 ) ( a ) C. Heidelberger, N. Iz. Chaudhuri, P. Danneberg, D. Mooren, L. Griesbach, R. Duschinsky, R. J. Schnitzer, E. Pleven. and J. Scheiner, Nature, 179, 663 (1957); (b! R. Duschinsky, E. Pleven, and C. Heidelberger, J . A m . Chem. Sac., 79, 2559 (1957). (6) (a) C. Heidelberger, L. Griesbach, B. J. Montag, D. Mooren, 0. Cruz. R. J. Schnitzer, and E. Grunherg, Cancer Res., 18, 305 (1958); (h) F. J. Ansfield. J. M. Schroeder, and A . R. Curreri, J . A m . M e d . Assoc., 181, 295 (1962). ( 7 ) (a) N. K. Chaudhuri, K. L. Mukherjee, and C. Heidelberger, Biochem. Pharmacol., 1, 328 (1958); (b) K. L. Mukherjee and C. Heidelherger, J . B i d . Chem., 236, 433 (1960): (e) K. L. Mukherjee, A. R. Curreri. 31.Javid, and C. Heidelberger, Cancer Res., 23, 67 (1963). 18) N. K. Chaudhuri, B J. .\Iontag, and C. Heidelberger, ibid., 18, 318 (1958). (9) (a) C. Heidelberger, G. Kaldor, K. L. Mukherjee. and P. B. Danneberg, ibid.. 20, 903 (1960): (b) K-U. Hartmann and C. Heidelberger. J . B i d . Chem., 236, 3006 (1961).
(10) (a) C. Heidelherger, L. Griesbach, 0. Cruz, R. J. Schnitzer, and E. Grunberg, Proc. Soc. Ezptl. Bid. itfed,, 97, 470 (1958); (b) F. J. Ansfield, J. 31. Schroeder, and 4 . R. Curreri. Cancer Chemotherapy R e p t . , 16, 389 (196?). (11) (a) F. Weygand, A. Wacker, and H. Dellaeg, Z . Satur/orsch., 76, 19 (1952); (b) 8.Zamenhof and S . Griboff, 3ature. 174, 306 (1954); (c) 11. L. Eidinoff, L. Cheong, and M. A. Rich, Science, 129, 1550 (1959): (d) W. H. Prusoff, J. J. Jaffe, and H. Giinther, Biochsm. Pharmacol., 3, 110 (195Y). (12) (a) S. Benzer and E. Freese, Proc. .VatZ. Acad. Sci. U. S., 44, 112 (1958); (b) V. Djordjevic and W.Szybalski, J . Ezptl. :?fed., 112, 509 (1960).
1
prepaiztioiis of several other trifluoroinetliylpyriiiiidines I\ ere described.13a-e but none of these conipourids had the trifluoromethyl group in the crucial 5-positioii After our coiiiiiiunicatiori of the original syiithesis had becii accepted, l b 17eit14described the syiitlie triAuol.oniethyl-j-~iydroxy-~,~-dihydrouracil,but lit5 was unsuccessful in attempts to convert it into ;trifluoi oiiiethyluracil. Tery recently, Nertes and Sa. licblj Iiave aiitiouiiced the preparation of 5-trifluoroiiicthylui acil in oiie step fi,oiii .i-carhosyiii~icilby troatnieiit n-itli sulfur tetrafluoride. The synthetic pathway that iras ultimately succesrful is shou i i helow and i.; a considerable iiiodificatioii of a r w y early syiithesis of thymine described by 1;ischer and Roedei.. I f i That synthesis involved tlic coadexiization of iiirtliacrvlic acid with uiea t o gi\ E dihydrotliymiiie, m liicli IT as broniiiiated aiid deliydi ohromiinted to give tliyiiiiiie. I-Tonever. trifluoiw iiicthacrylic acid" failed to give a reaction with u i w i f i 0111 ~rhicha product could be kolated. Severtlieless, hy iiiakiiig various compounds related to nietliacarylic acid, the synthesis ultimately wah siicce~sfiil. CL
CK
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-
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(13, [ a i .I. (.;iner-Sorolld and .\. Ben.lic1l, .J. .lm Cltem. S O ~ .80. , 37-14 ( i Y j 8 ) ; ibl c'. Heidelberper and 31. E:. Bariiiiann, Cancer R e s . S u p p l e m e n t , 3, :373 (19.X): ( r ) .J. .i. Barone, E. P e t e r s , and H. Tierkpiniann. J . O w . CAem., 24, 198 ( I % > ! < ) : ((1) 3. Inoue, I.,' .J. 4.iO-1 ( 1 S S l l : (el ,I. A. Baronr. .I. .ll ( 1 s ) 1.' \V.i'eit, A r c h . Pltaim., 295, 321 (lQ62). (1.5) 11. 1'. \Iertrs and J. I:. SallPb, J . Pharm. S r i . . 52. .io8(l!lO i i . 110, I?. r i q c l i e r a n d G . Koeder, Bei.., 34, 3731 (1901). (17) 31. \IB u. r t o n , 11. Stace?, a n d J. C . Tatlon, .I. ( ' h v m . (1954).
January, 1964
T TRIFLE OR OM ETHYL URACIL
AND ~?I-TRIFLUOROMETHYL-~'-DEOXYURIDINE
we have prepared the corresponding uracoyl derivatives of glycylglycine (XIV) and glycine (XV). We do not anticipate that these latter two compounds will have any significant biological properties. 5-Trifluoromethyluracil-2-C14 and j-trifluoromethyl2'-deoxy~ridine-2-C~~ of high specific activity were synthesized from 100 me. of barium ~arb0nate-C'~ for biological and biochemical investigations. The expectation that these compounds might have been interesting biological properties has been borne out. 5-Trifluoromethyl-2'-deoxyuridine is incorporated into the DKA of bacteriophage T4B, resulting in a greatly increased mutability.21ab It is also incorporated into the D S A of mammalian cells grown in vitro, thereby producing a significant radiosensitization.22 The nucleoside is a competitive inhibitor of the cleavage of 5-fluoro-2'-deoxyuridine by the enzyme 2 3 and in the nucleotide nucleoside form it inhibits the enzyme, thynlidylate synthetase.*la 3-Trifluoromethyl-2'-deoxyuridine is also a powerful inhibitor of the growth of Adenocarcinoma 755 in
Experimental Melting points are corrected. Microanalyses by Spang Microanalytical Laboratories, Ann Arbor, Mich. 2-Cyano-2-hydroxy-l,l,l-trifluoropropane (Trifluoroacetone Cyanohydrin) (I),-A solution containing 115 g. (2.30 moles) of sodium cyanide in 500 ml. of water was cooled to O", and 250 g. (2.22 moles) of l,l,l-trifluoroacetone (Peninsular Chemical Corp., Gainesville, Florida) waa added slowly with stirring, and the temperature was kept below 15". T o this solution was added 810 ml. of 6 iYsulfuric acid dropwise over a period of 3 hr. while the temperature was maintained a t 5-10'. A heavy precipitate of sodium sulfate formed, and the mixture was allowed t o stand overnight. The darkly colored lower phase was separated, and the aqueous layer was extracted three times with 300 ml. of ether. The combined ether extracts and lower phase were washed with water and dried over anhydrous magnesium sulfate. The ether was distilled a t atmospheric pressure and the crude cyanohydrin was distilled t o give a yield of 305 g. (99%) b.p. 60-80' (25 mm.). 2-Acetoxy-2-cyano-l,l,l-trifluoropropane(II).-A mixture of 250 g. of I and 250 ml. of acetic anhydride containing 0.5 ml. of concentrated sulfuric acid waa refluxed for 1 hr. The excess acetic anhydride was destroyed by the addition of 20 ml. of water, and the mixture was cooled and poured on 1500 ml. of ice and water. The lower layer of ester was separated, and the aqueous phase was extracted twice with ether, the combined extracts were dried over anhydrous magnesium sulfate, and fractionally distilled. The fraction boiling from 145-154' was collected, and 255 g. (78%) was obtained. 2-Cyano-l,l,l-trifluoropropene (Trifluoromethylacrylonitrile) (III).-2-Acetoxy-2-cyano-l,l,l-trifluoropropane (11, 150 g.) was pyrolyzed in a vertical borosilicate glass tube, inside diameter 1.7 em. and packed with glass tubes 1 cm. X 0.2 mm. for a length of 40 cm. The tube wm heated in a 32-cm. furnace and maintained thermostatically a t 500°, and the ester was passed through the tube over a period of 4 hr. in an atmosphere of nitrogen. The products were collected in a trap cooled in ice and salt, and 64 g. of I11 (64%) was collected by fractional distillation a t 72-79 O. p-Bromo-a-trifluoromethylpropionamide(IV).-A mixture of 34.8 g. (0.288 mole) of I11 and 12.1 ml. (0.298 mole) of absolute methanol (dried over calcium hydride) was cooled in an (21) (a) C. Heidelberger. H. Gottschling, and G. D. Birnie, Fedemticn P ~ o c . 24, , 532 (1963); (b) H. Gottschling and C. Heidelberger, J . M o l . Biol.,
in press. (22) W.Szybalski, N. Cohn, and C. Heidelberger, Pederation Proc., 22, 332 11963). (23) C. Heidelberger, G. D. Birnie, J. Boohar, and D. Wentland, Biochin. Biophys. Acta, 76, 315 (1963). 124) C. Heidelbergrr and S. W. Anderson, unpublished.
3
ice-salt bath, and hydrogen bromide was slowly bubbled into the solution until the theoretical amount was absorbed (2-3 hr.) (cf. ref. 25). The viscous reaction mixture was then stored in the refrigerator for 36 hr., and then evacuated (water pump) a t room temperature until all bubbling ceased. The semisolid reaction mixture was then heated under vacuum t o 100" until bubbling stopped. The melt was poured into a large mortar, cooled, and ground with water. The solid was filtered, dried over NOH in a vacuum desiccator, and 47.3 g. (827,) was obtained of a product sufficiently pure for the subsequent condensation reaction. The product was recrystallized from water to give an analytical sample, m.p. 106-107". Anal. Calcd. for CaH5BrF,SO: C, 21.9; H , 2.29; S , 6.36: F,25.9. Found: C,22.0; H,2.39; S , 6 . 5 2 ; F, 25.8,
p-Ethoxycarbonylamino-a-trifluoromethylpropionamide(V).X mixture of 7.0 g. of I V and 4.0 g. of urethan was dissolved in 18 ml. of redistilled dimethylformamide and cautiouslj- heated t o 120°, when the reaction started and the temperature spontaneously increased t o 130". The mixture was heated a t 140" for 2 hr. until the evolution of hydrogen bromide had ceased, during which time the product started to crystallize. The dimethylformamide was distilled zn uacuo, and the resultant solid residue was crystdlized from water t o give 6.0 g. (82'3), m.p. 179180". Anal. Calcd. for C7HllF3N203:C, 368; H, 4.85,F, 24.9; N, 12.3. Found: C, 36.8; H, 4.69; F, 23.4; N, 12.7. p-Ethoxycarbonylamino-drifluoromethylpropionicacid (VI). -Amide 5' (4.0 g.) was heated under reflux in 20 ml. of hydrochloric acid for 4 hr. On cooling, 1.6 g. of a crystalline product was obtained and was recrystallized from water t o give glistening plates, m.p. 80". Anal. Calcd. for C7H10F3XO4: C, 36.7; H, 4.40. Found: C, 36.3; H , 4.73. a-Trifluoromethyl-6-ureidopropionamide (VII).-A solution of 4.49 g. (0.204 mole) of 15' in 15 ml. of hot water \?as added dropwise to a solution of 2.4 g. (0.40 mole) of urea in 10 ml. of water for 40 min. a t 60". The temperature was raised to 100" for 30 min., after which time a bromide determination on the solution showed that the release of hydrogen bromide was complete. The solution was then evaporated in tacuo a t 35" t o give a sirup that was redissolved in ethanol, which was evaporated under vacuum a t 30" to leave a solid residue. The crude product wab recrystallized from water (charcoal) to give 1.15 g. (28TC) of white needlee, m.p. 170-172". A sample was recrystallized for analysis from ethanol, m.p. 172-173'. Anal. Calcd. for C5H8F3S302 CgHbOH: C, 34.3; H, 5.72; N, 17.14; F,23.2. Found: C,33.9; H , 5.18; X, 17.3; F, 23.6. When equivalent amounts of the bromo-amide and urea mere coi,densed, the product obtained in largest yield r.elted a t 246'. This compound was most probably the disubstituted urea, but was not further characterized. p-( N-Acety1ureido)-drifluoromethylpropionamide( V111).-A4 mixture of 10 g. (0.454 mole) of II' and 7.5 g. (0.T35 mole) of N-acetylurea in 35 ml. of dimethylformamide was heated to 120" for 3 hr. The orange-red solution %as evaporated under vacuum a t 50" to give a solid residue, m hich was crystallized from 250 ml. of hot water with charcoal, t o form needles, m.p. 206208", jield 6.3 g. (57%). The analytical sample was recrystallized from ethanol, m.p. 209-210'. Anal. Calcd. for C1H1QF3X3O3: C, 34.9; H, 4.17; F, 23.6; N , 17.4. Found: C,35.0; H,4.20; F, 23.5; S , 17.7. 5,6-Dihydro-5-trifluoromethyluracil (IX). A,-The ureidoamide VI1 (0.90 g.) was heated under reflux in 5 ml. of 5 A* hydrochloric acid for 1 hr. The reaction was cooled and the hydrochloric acid removed by evaporation in vucuo a t 35'. The residue was shaken with 10 ml. of ethanol, and again evaporated t o dryness in z'acuo. The solid obtained was crystallized from water t o give 0.48 g. (58%) of small white prisms, m.p. 203-205" dec. Anal. Calcd. for C6H6FzP\T2O2:C, 33.0; H, 2.77; F, 31.3; N, 15.4. Found: C, 33.1; H, 2.81; F, 31.3; N, 15.2. B.-The N-acetyl-ureidoamide VI11 (6.3 g.) was refluxed in 25 ml. of 5 LVhydrochloric acid for 90 min. The reaction was filtered, the filtrate evaporated to dryness under vacuum a t 40°, 25 ml. of water was added, and the mixture evaporated. Finally ethanol was added and the mixture was re-evaporated t o remove all traces of HC1. The residue was recrjstallized from mater ( 2 5 ) S.
(1947).
RI. 3lcElvain and C. L. Stevens, 1. A m . Chem.
Soc., 69, 2663
t i l give a p r i ~ d ~ i t i~e nt t i d \\-it11 that ol)t:iinetl 1i.v niethod A, yield? 3 . 3 g. ( 6 9 5 ) . 5-Bromo-5-triiiuoromethyl-6-hydrouracil(Xj.-..4 solutiim of 0.W g. ( 4 . 1 niiiioles) of I S in 8 nil. of glacial :tc.etic. :wit1 \V:J,V 1ie:itcd under gentle reflux, and 0.80 g. (5.0 niriioles) r i f 1)roniiiic' i n 10 nil. of acetic :&rid%-:is added dropwise. . M e r dtlitiiiri ( i t the Iironiine the solution \vas refluxed for Y hr. t o givc :I 1i:ilo y e l l c i ~solution, which was evaporated to dryriess, anti the rositliii. \v:ts dissolved in ethanol itrid T h e criitle prodnc*t weighed 0. f r o i n :tqueoiis ethaiiiil t o give t
(c1i:trcii:iI~
(26) ;a) ,I. 1,;. C;t.arien and P. 13. Binkley, J . Org. Clieni.. 23, 491 (19:Xi: Ih) W. Gabel and S. R. Binkley, i h i d . , 23, 6-13 (1958J. ( 2 7 ) J. 1;. Codinaton, I . Doerr. I). Van Praai., .\. Rendiclr, and .J. .I. I'iix. .I d m . Chem. SOC., 83, ,5030 (1861).
\-.
PYRIMIDINES. V
January, 1964
stirred at room temperature for 24 hr., the volume reduced t o 20 ml. in vacuo, and a yellowish semicrystalline compound was collected after standing for 3 hr. at 3". This compound was crystallized from water (charcoal), and a yield of 0.35 g. (207,) was obtained, m.p. 295' dec. d n a l . Calcd. for C,HiN30j: C, 39.4; H, 3.32; S, 19.7. Found: C, 39.2; R,3.49; Xi 19.5. Ultraviolet absorption spectrum; in 0.1 L Y hydrochloric acid, , , A, 271 m p ( E 10,700); A,, 241 nip ( E 3160); ,,AI, 220 mp ( E 11,400); in 0.1 -1-sodium hydroxide,, , ,A 291 mp ( E 14,600); A,i, min 260 mp ( e 3290); A,, 240 nip ( e 10,200). Paper chromatography: Rf 0.14 in butanol-water, 86:14; Rr 0.36 in butanol-acetic acid-water, 5: 3 : 2 . Preparation of 5-trifluoromethyluracil-2-C'( and 5-Trifluoromethyl-2'-deoxy~ridine-Z-C~~.-Barium carbonate-C14 (100 me.) was diluted with nonradioactive barium carbonate t o give a total of 4.5 g. This was converted in two batches into barium cyanamide by heating for hr. a t 850" in a slow stream of ammonia gas, and 4.0 g. was obtained.2B Water (20 nil.) was added to the barium cyanamide, the bigger lumps were crushed, and the suspension was cooled to 5". Sulfuric acid was added dropmise with stirring until the p H reached 7.0 and the barium sulfate \vas removed by centrifugation. The supernatant solutions and the mshings from the barium sulfate were combined and the aqueous solution was concentrated to a small volume i n vacuo at 30". The cyanamide was converted into urea23 by treatment of 10 nil. of solution with 1.5 nil. of concentrated hydrochloric acid and refluxing for 10 Inin. The solution was cooled, neutralized with sodium bicarbonate, and evaporated t o dryness in vacuo. The residue v a s extracted with five 20-nil. portions of boiling absolute ethanol, and the combined extractswere evaporated to20ml. and cooled. The small amount of sodium chloride present was filtered, and the filtrate was evaporated t o dryness t o give 1.105 g. (81%) of urea. The urea was acetylated with a mixture of 1.S5 ml. of acetic anhydride, 0.75 ml. of acetic acid, and 0.02 ml. of concentrated sulfuric acid, which was heated to 130" for 10 niin. and allowed to cool. The S-acetylurea crystallized, was (28) S. 11. Zbarsky and I. Fischer, Can. J . Ren., N B , 81 (1949).
Pyrimidine Derivatives. V.
5
dissolved in 30 ml. of water, psussed through a 1.5 X 20 em. column of Dowex-1-formate, and eluted with 80 ml. of water. The solution was evaporated t o dryness, and the S-acetylurea wns crystallized from water to give 1.615 g. (86%). The S-acetylurea (0.016 mole) and 2.38 g. (0.011 mole) of IT were dissolved in 15 nil. of redistilled dimethylforniamide and heated for 3 hr. a t 125". The solvent was evaporated in Paczio, and the residue was crystallized from water (charcoal) to give a j-ield of 1.02 g. (40%) of lebeled 1-111. This was then heated hj-drochloric acid for 1 hr. and under reflux in 15 ml. of 5 evaporated t o dryness in cacito. The residue was crystallized from water (charcoal) to give 290 nig. ( 3 8 5 ) of dihydrotrifluortrniethyluracil-2-C14. S o additional crystalline material could be obtained from the mother liquors. Thus, 290 nig. w:?s dissolved in 10 nil. of glacial acetic acid and brominated lyith 600 mg. of bromine in 6 ml. of acetic acid at reflux temperature for 90 niin. T1:e bromine and acetic acid Tvere evaporated in z~ucuo,and the residue was coevaporated 3 tinies with absolute ethanol and heated in 10 nil. of dimethj-lformamide at' 130" for 1 hr. After evaporation of the solvent in cucz(o and coevr,por:i.tion with water, the residue as passed through a 1.5 X 20 cni. colunin of I)owex-l-forniate, and after elution of impurities with !niter, the 5-trifluoromethyl-2-C'" uracil wes eluted with 0.05 JI forniic acid. The solution was evaporated to drj-ness, ccevapor7,ted with water to give 242 mg. (85%) of product that gzve only a single radioactive spot in three paper chromatographic systems. The over-all j-ield, based on barium carbonate, was 5.9:;. The specific activity was 4.15 nic./mmole (23 pc./mg.) The labeled 5-trifluoromethyluracil (234 nig.) was converted to the deoxyribonucleoside with an enzyme obtained from Lacfobacillus Leichnzanii, kindly provided by Dr. Jack Siege1 of the Pabst Laboratories, l\lilw.eukee, Wis., and was purified as described above to give 15s mg. (41%) of 5-trifluoroniethyl-2'deoxy~ridine-2-C'~, which gave only a single radioactive spot in three paper chromatographic systems, and had a specific activity of 4.15 nic./mniole (14 pc./mg.).
Acknowledgment.-We are grateful to Nrs. Sancy W. Remy for skillful and devoted technical assistance.
Synthesis of Substituted Pyrimidines from
4-Amino-6-chlor0-2-methylthiopyrimidinel -3 ~ I E R V P ISRAEL, N HELJO&SGUR
PROTOPAPA, HERBERT s.SCHLEIN, 4 S D EDWARD J. ~ I O D E S T
T h e Children's Cancer Research Foundatzon, and the Departments of Pathology and Bzologzcal Chemistry, H a r m r d Jfedzcal School at The Chzldren's Hospital, iYoston, Massachztsetts Receiced X a r c h 15, 1563 Reuised ?danuscript Receiz,ed October 11, 1563 The use of 4-amino-6-chloro-2-methj Ithiopj-rimidine as a versatile intermediate for the synthesis of a number of substituted pyrimidines is described. I n the course of this work several previously unreported pyrimidines have been prepared. Feigl's iodine-azide reagent has been emploj-ed for the rapid detection of mercaptopj-rimidines and a sponge nickel catalyst has been found to be quite satisfactory for the facile dethiation of these derivatives. Quantitative ultraviolet absorption spectra are given for all compounds, as me11 as a summary of growth-inhibitory properties in several in vitro and zn tizo bioassaj- systems.
For some time a program of synthesis of pyrimidine derivatives for biological evaluation has been in progress in these laboratories3 and, in connection with this program, the preparation of various pyrimidines as potential cancer chemotherapeutic agents and as precursors of condensed pyrimidine systems has been undertaken. This communication describes the syn(1) This investigation was supported in part by reeearch grants (CY3335 and (26516) from the National Cancer Institute, Piational Institutes of Health, L-. S. Public Health Service. ( 2 ) A preliminary report of part of this work has been presented: E. J. Modest and H . N. Schlein. RBsum6s des Communications, 3me Congres International de Biochimie, Bruxelles, August 3, 1955, p . 33. (3) For paper IV in this series see E. J. Modest, S. Chatterjee. G. E. Foley, a n d S. Farber, Acta, Cnio Intern. Contt-a C a n c r u m , in press.
thesis of a number of substituted pyrimidines starting from the versatile intermediate 4-aniino-B-chloro-2methylthiopyrimidine (111), which was prepared following the method of Baker, et aL4 4-Amino-6-hydroxy-2-niethylthiopyrimidine (11) was obtained by reaction of thiourea and ethyl cyanoacetate, with methylation in situ of the anion of 4-amino6-hydroxy-2-mercaptopyrimidine (I) by means of freshly distilled dimethyl sulfate. The use of aged dimethyl sulfate led to the isolation of I5as a by-piod(4) B. R. Baker, J. P. Joseph, and R. E. Schaub, J . Org. Chem., 19, 631 (1954). ( 5 ) 'K. Traube, Ann., 331, 64 (1904).
