:iloyl c l~ lu r i t i e~~ (nip 113 115") w:is htirrctl :it, ?,jo f11r :j lir. 'Flit. colorless mixture turned dark red iti XI niiii theti hecanie light yellow in 3 hr. Various amino acids required :3-8 hr for this color cllange. The solution was treated with decolorizing carbon :it t i l filter aid, filtered, and brought to pH 4 with concentrated HCI, cooled a t 10" for 12 hr, and filtered to give 6.94 g (85.57;) of white pctwder, mp 230-231", [a] 26n + SaEIC03). Tlie product was recrystallized froni hot wvater t (i give 4.S0 g (59.47,) of analytically pure material, mp 237-23X0, [ C Y ] ~ ~ D 4-123.7" ( c I, aqueous 5% XaHCOa).

7" ( e 1, aqueous

(10) 11. C. Iiogpel, I. L. Honigbery, 11. 11. Springer, and I:;. C . Clianrt .J. Org. Chem. , 28, 1119 (1963).

The Acet>lation of l-(P-u-Arabinoruranos?.l)c?-tosine'

The tri-0-acetate (11) and the tetraecetate (111) of 1-($-u- :~r~tbinofuranosyl)cyto5i1ie ( I ) have been prepared as compounds tha t may be pharmacologically niore useful forms of I 1% hirh ha i antitumor properties.2 The tri-0-acetate mas obtained by selec- tive acetylation of the hydrochloride of I under mild conditions. Standard acetylation conditions readily converted I to 111.

RO I, R = 1:' = I1

11, It = hv; R ' = I1 111. 11 = It ' = h c

Experimental Section3

1-(2,3,5-Tri-0-acetyl-~-~-arabinofuranosy~~cytosine (H).--.i -elution of acetic-trifluoroacetic anhydride wab prepared by

(1) This work was carried out under the auspices of the Cancer Cheino- therapy Xational Service Center, National Cancer Institute, h-ational Insti- tutes of Health, Public Health Service, Contract No. PH-43-64-600. The opinions expressed are those of the authors and are not necessarily those of the Cancer Chemotherapy National Service Center.

( 2 ) (a) R. IT. Talley, and V. I(. Vaitkevicius, Blood, 21, 362 (1963); ( b j .J. 5. Evans, E. h. Nusser, L. Bostxick, and G. D. Mengel, Cancer Res., 24, 1285 (1964); (r) .J. E. Evans, L. Bustwick, and G. D. hlengel. Biochem. I'harmacol., 18, 983 (1964).

( 3 ) Melting points M-ere determined on a Fisher-Johns apparatus and are uncorrected. Anhydrous bIgSOa was used as the drying agent. Paper cliromatograms were run by the descending technique on Whatman KO. 1 paper and the spots were located in R . A ~ units with adenine a t 1.00. The solvent systems were: A , 1-butanol-water (saturated); B, water; C, 1- hutanol-acetic acid-water ( 5 : 2 : 3 ) . Thin layer chromatograms were run on silica gel €IF plates with a solvent system of methanol-CHCls (1:4). The spots on plates and paper were detected by ultraviolet light. Optical rota- tions a e r e determined in 1 % solutions in N,iV-dimethylformamide a t 2 1 . 6 O iising the sodium D line. Tlie nmr spectra were determined with a Varian . \ - f iO spectrometer. using CI3Clz solutions containing 4y0 Si(CHa)r as internal standard. The spectra of I1 and 111 were compatible nitl! the i r st rlic; tures.

i i i i \ i i ig l . !1 (1 g (!JI n i i r i ~ i k ~ ) ( i f tritkuoro:icetic: :itdiydride a i d (0.52 t i i i ~ l ~ ) i i f acetic acid :tiid allowing IY)OIII temperature for 30 miri. Thr 3

>louiy :tdded (over d iou t 10 rriiii) i o :L rrinioles) of I.HC:I ill 35 nil of triflucironi.ciic. : i d 4 - ( I 1IMl 1111.

temperature did riot rise above IO". After 30 miri at 10' : i t 1 (1

aliout 11' fir ai ruom t,emperat,ure,s the c*lear solution \vas c ~ ~ o h v l and thc temperature maintained below 25' during treatrnctit s - i t l i , ~ . a in1 of absolute ethanol t(J decompose exress atihydridr. :Wer 0.5 hr at, room temperat,ure, the solution \vas evaporated i i r ~ ( I C I I ~ (water-bath temperature 4(MOo). The residue \vas dissolved in G O ml of water and neutralized to 6 with solid TaHC03. Thc :tqueous solution0 \vas extracted witli 115-0 4jO- nil portions of (!thy1 ai:etate' wliic~li were combined, dried, :rr!ti concentrated ttr ahout 90 ml t.o afford ?.36 g (60%) o f higlrly crystalline TI, mp 189--1YDo, homogeneous I,? thiii layer i,lironi:i- tography. Evaporation of the ethyl acetate filtrate nt'fordcd 0.82 g (21:;,] (if amorphous produci,, mostly I1 with a trace of IC,+

A\ third ethyl acetate extract o f th r aqllcolts h i~ lu t i~~i i afforded ().'$7 g more of material that. wa> co~i~pos:c~l cii '

I1 nil t i less :teyIatc(l material in al~iint, ccliial anloutit.?. product froni :t Iirevious ruti n i r l i c ~ ~ l i y l

he :malytical sample of 11: Inp 18!).0-1S0..io : ,3.20 (X-I-r), 5.i2 (C=Oofit t .etatej; ? C X ' 2 W : A:;,::~' 233 In@ ( E S.1 x 103), 270 (9.1 x 1 0 ~ ) ; ~ 0.11 x 105); ( a ] j t l i i " . The niethyl prot.ott3 were lorated between T 7.83 arid S.01. I t \V:LS

liomogeneous I J ~ 1 liin la)-er chromatographg and by paper c1irornatogra1h.v i r i t liese solvent;: ;I, X,I 1.44, and 13, / ~ A , I 2.43.

A 4 ~ ~ a l . Chlcd for Cli1-Il,S308: C, 48.8; 11, 5.t9; 5, 1 l . i . Found:

1-~2,3,~-Tri-0-acet~l-~-1)-arabinofuranosyI)-,\' '-acetylcytosine (111'). - A ~i~lu t io i i ( i f ' 1 .70 g of I.HC1 in 180 nil ( i f dry pyridiiics \v:w rreated with 15.0 nil I J ~ :wetic anhydride (blight wvarmiitgj. The re>ult:itit solution left c~vernight (about '10 hr ) :it ~ O I I I I I

tenipernture atid w:tr tli waporated in z~cicuo (hatli terriper:rl rive .t.j -50"). The residue ~va" treated with 20 nil of a b d u t e eth2iltldJ diluted wi th 150 nil of toluene, and again evaporated t o dryness. The residue wts partitioned between 300 ml of ethyl acetate and 1 ~ 1 tnl of r a t e r . The ethyl acetate layer was washed with water, dried, coilcentrated to 50 ml, and then diluted 10-fold with et her. The product which crystallized \vas collerted, washed with ethyl acetate--ether (l:lO), and dried to afford 5.86 g (85; ; ) of 111, nip 171-IXo, homogeneous by thin layer and paper chromatography. i<ecrystallization froni ethyl acetate-ether afforded the analyticalexample of 111: mp 171-171.5"; A:;:"' ( p )

3 (acetate); Xzx' 247 nip ( e 11.2 X IO3), 17 mp f c 16.4 X l O 3 ) , 298 (8.6 X IO3);& 1 0 3 ) : i n ] -+ Si". The niet,hyl protoitd

of the C)-acet;ites :ippcared a1 7 7.%&8.01; the S-acet)'l, at 7

7.6T. 11 iiiovcd a,? :t sir@ spot iii thin layer chromatogrunis (lt'i o.%)) : r i i d o n 1~:aprr i r r these solvents: A. R.,,t 1.75, and C. I$.,,l 1

1111

- -

led m:tterisI.

I:ecryatalli/,alir,ri

C , 48.5; FI, 5 .22; S, 11.5.

- -

Acknowledgment.-The :trithors 1 hank Ur. Peter Lin! : i l l t i

his staff for the ultraviolet, and infrared spectr:i, optic,:d roi:i- iioiw, atid pq jer vliromatography.

(4) T h e l~y(!rocliluriilc~ (if 1 wits soluble in triHutiroacetic ai~ii! L i i i t U ( J ~ i n acetic acid, acetic anhydride. mixtures of these two, or in the solution of acetic-trifluoroacetic anhydride.

( 5 ) Aliquots were periodically examined by thin layer cliromatograyiiy for complereness of reaction. Compound I1 (Rr 0.66) was readily distin- guished from less acylated products (Rr 4 0 . 5 ) .

(6) I n one preparation of 11, the product wasleft in water overnight. Tlie yield of I1 was Ion , suggesting tha t considerable amounts of I1 had hydro- lyzed.

(7) Ethyl acetate cannot be replaced b y CHC13. I t was inefficient for extracting the quite water-soluble I1 from the aqueous phase.

( 8 ) J. B e r h e k and ,I. Piiha, Collection Czech. Chwn. Commun., 29, 625 (1964), have reported the ultraviolet spectra in ethanol for 2',3',5'-tri-O- acetylcytidine (Aniar 243 and 288 mr) and .V~-acetyl-2',3'-5'-tri-0-arPt?.l- rytidine (Arnsx 249 and 299 mr) .