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The antiviral activity of 5-methoxymethyl-2'-deoxyuridine (MMUdR) was compared with that of 5-iodo-2'-deoxyuridine (IUdR), 5-ethyl-2'-deoxyuridine (EtUdR), adenine arabinoside (Ara-A), and phosphonoacetic acid (PAA) against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). MMUdR was more potent than Ara-A and PAA but less active than EtUdR and IUdR against HSV-1 in rabbit kidney (RK-13) cells. In Vero cells, the antiviral activities of MMUdR, Ara-A, and PAA against HSV-1 were of the same order of magnitude. The antiviral potency against HSV-2 varied with the strain of virus used. All strains of HSV-2 were markedly inhibited by EtUdR and IUdR and to a lesser degree by PAA. However, considerable variation was noticed in the susceptibility of HSV-2 strains to Ara-A and MMUdR. Interaction of MMUdR with Ara-A, EtUdR, IUdR, and PAA was investigated by the method of response isobolograms. MMUdR showed synergistic activity in combination with Ara-A and PAA but antagonistic activity in combination with EtUdR and IUdR against herpesviruses. Minimum toxic dose (concentration required to produce definite evidence of microscopic cytotoxicity in rapidly growing RK-13 cells) was determined for each compound and was found to be 512, 172, 64, 8, and less than 0.5 microgram/ml for MMUdR, PAA, Ara-A, EtUdR, and IUdR, respectively. MMUdR was found to have the maximum antiviral index against HSV-1 (512) and HSV-2 strains X-265 (102) and ATCC (85). Antiviral index was defined as the minimum toxic dose divided by the dose that reduced plaque numbers by 50%.

Tetrahydrofolate reacted rapidly with 5chloromethyluracil (unlabeled or 2-14C) in dioxanephosphate buffer (pH 7.0) at 5" to yield predominantly 5-thyminyltetrahydrofolate (I). The latter compound was isolated by chromatography on DEAE-cellulose and crystallized as the free acid or the barium salt. Under similar conditions, folate was converted to the 10-thyminyl derivative (11) which was also isolated as the crystalline acid. Catalytic hydrogenation of I1 in glacial acetic acid over platinum oxide yielded 10thyminyltetrahydrofolate (111). In contrast to I, I11

The synthesis and properties of ether derivatives 6a-dof 5-hydroxymethyldeoxyuridine and their corresponding a-anomers 7a-d are described. Acid-catalyzed etherification of 5-hydroxymethyluraci1 (1) gave the corresponding 5-alkoxymethyluracils 2a-e in excellent yields. Treatment of compounds 2a-e with trimethylchlorosilane gave bis(trimethylsilyl)pyrimidines 3a-e in high yields which, upon condensation with 3,5-di-(0-p-to1uoyl)-2-deoxy-D-ribofuranosy chloride, furnished an anomeric mixture of substituted nucleosides, p-anomers 4a-e and a-anomers 5(a-e). The nucleosides with p-configuration were the major products in each case and were recovered as crystalline solids in good yields. Deblocking of compounds 4a-d by alcoholysis resulted in the corresponding ether derivatives 6a-d. From mother liquors, two substituted a-anomers, 5a, b were isolated as crystalline solids in small yields. Compounds 7c, d were obtained from mother liquors after hydrolysis by using preparative t.1.c. The structures were confirmed on the basis of p.m.r. studies, U.V. and i.r. absorption spectra, and elemental analysis. The compounds 2a-e and 6a-d did not inhibit thymidylate synthetase at a concentration of 2.5 mM. Canadian Journal of Chemistry, 48, 3147 (1970)The hydroxymethylpyrimidine deoxyribonu-corresponding blocked p-anomers 4a-e, and cleotides are unique constituents of viral DNA a-anomers, 5a-e; the p-anomers predominated (1-5); furthermire, 5-substituted pyrimidines have been suggested as possible intermediates during the transformation of thymine to RNA pyrimidines (6). The hydroxymethylation of pyrimidine deoxyribonucleotides is carried out by specific hydroxymethylases; the hydroxymethyl group originates from the Cl-unit of 5,lO-methylene tetrahydrofolic acid (7, 8). In this commuilication we report the synthesis of 5-substituted ether derivatives of 5-hydroxyin all cases.4 After removal of the silyl groups by aqueous ethanol, p-anomers IV (a-e), were isolated from the reaction mixture as crystalline solids in good yields (45-72 %). The F-configuration was assigned to 5-alkoxymethyl deoxyribonucleosides 4 (a-e) on the basis of a characteristic triplet in the p.m.r. spectrum; it exhibited a coupling constant (J,,,,, = J,.,,., of 7.0 + 0.1) c.p.s. for the anomeric proton at 6 6.30-6.35. Treatment of the substituted nucleosides 4a-e methyldeoxyuridine and their corresponding &-with hot sodium methoxide in methanol or with anomers (Scheme 1). We have prepared these ethanolic sodium hydroxide at room temperacompounds for the study of the bulk tolerance ture gave the corresponding 5-alkoxymethyl deof thymidylate synthetase to substituents on the rivatives of deoxyuridine 6a-e in excellent yields 5-position of the pyrimidine ring.(75-85%). In compounds 6a-e the signal of the The conversion of 5-hydroxymethyluracil (1) anomeric hydrogen (1 '-H) appeared in the form was successfully modified (9) to obtain 5-alkoxy-of a triplet as 6 6.16 with a coupling constant of methyluracils 2a-e in excellent yields (92-97%). J,,,,, = J,,,,., = 6.95 ...