Nucleosides. CXXXV. Synthesis of some 9-(2-deoxy-2-fluoro-.BETA.-D-arabinofuranosyl)-9H-purines and their biological activities.

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Abstract
Seven purine nucleosides containing the 2''-deoxy-2''-fluoro-.beta.-D-arabinofuranosyl moiety were synthesized and tested for their antitumor activity. Direct condensation of 3-O-acetyl-5-O-benzoyl-2-deoxy-2-fluoro-D-arabinofuranosyl bromide (1) with N6-benzoyladenine in CH2Cl2 followed by saponification of the product afforded the adenine nucleoside (I, 2''-F-ara-A). Deamination of I with NaNO2 in HOAc gave the hypoxanthine analogue (II, 2''-F-ara-H). The 6-thiopurine nucleoside (III, 2''-F-ara-6MP) was prepared by condensation of 1 with 6-chloropurine by the mercury procedure followed by thiourea treatment and saponification of the product. Methylation of III gave the 6-SCH3 analogue (IV). Raney Ni desulfurization of III afforded the unsubstituted purine nucleoside (V, 2''-F-ara-P). Condensation of 1 with 2-acetamido-6-chloropurine by the silyl procedure afforded the protected 2-acetamido-6-chloropurine nucleoside which served as the precursor for both the guanine and 6-thioguanine nucleosides (VI, 2''-F-ara-G and VII, 2''-F-ara-TG, respectively). Thus, alkaline hydrolysis of the precursor gave VI. Thiourea treatment prior to alkaline hydrolysis gave VII. The new nucleoside, 2''-F-ara-G (VI) is found to be selectively toxic to human T-cell leukemia CCRF-CEM.