No abstract

2 ',3 . (a). Perchloric acid (0.1 ml, 70%) was added to a stirred suspension of uridine (2.44 g, 10 mmol) in acetonitrile (10 ml) and acetaldehyde (5 ml) at room temperature. After 45 min a clear solution resulted and the solvents were removed in vacuo leaving 4 g of an oily solid. The latter was extracted several times with hot chloroform in order to remove aldehyde polymers leaving 1.9 g (70%) of crystalline 35. Recrystallization from ethanol gave 1.50 g (56%) of 35 with mp 194-196°u nchanged upon recrystallization (reported80 mp 194-195 °); XrH 260 nm (e 9900).(b). A solution of uridine (244 mg, 1 mmol) and 4 (0.49 g, 3 mmol) in DMF (1 ml) was kept at room temperature for 10 min. Solid sodium borohydride (300 mg) was added portionwise (frothing), and the semisolid mass was then diluted with chloroform, washed three times with aqueous bicarbonate and then water, dried, and evaporated leaving 370 mg of a syrup. This was treated for 1 hr with methanol-concentrated ammonium hydroxide (1:1, 4 ml) and then evaporated to dryness. The residue was separated into four bands by preparative tic using chloroform-methanol (9:1). The slower bands corresponded to uridine and 2'-chloro-2'-deoxyuridine while elution of the next band gave 43 mg (16%) of 35 which spontaneously crystallized. Recrystallization from methylene chloride gave 30 mg of a diastereomeric mixture of 35 with mp 183-185°. The nmr spectrum of the major isomer corresponded to that above while the minor isomer was readily distinguished by the appearance of CvH as a doublet (Jv%> = 2 Hz) at 6.32 ppm and of C¿H as a doublet (J5,e = 8 Hz) at 7.86 ppm.

The halo acetates obtained from ribo nucleosides and 2-acetoxyisobutyryl halides have been shown to readily react with chromous acetate and ethylenediamine in ethanol at -78°to produce 2',3'-dideoxy-d-D-gZycero-pent-2'-enofuranosyl nucleosides. In this way 2',3'-unsaturated analogs of adenosine, formycin, inosine, 5',A^-dibenzoylguanosine, and uridine have been prepared. Simple 3'-deoxy nucleosides and 3'-deoxy-/3-D-gZycero-pent-3enofuranosyl nucleosides are sometimes obtained as by-products. An alternative synthesis of the 3',4'-unsaturated analog of adenosine has been achieved via a base-catalyzed elimination reaction. Some interesting features of the nmr and ORD spectra of 2',3'-unsaturated nucleosides are reported. An alternative synthesis of 9-(2-0-acetyl-3-deoxy-3-halo-/3-D-xylofuranosyl)adenines has been developed uia the reaction of 2',3'-0-ethoxyethylideneadenosine with boron trifluoride etherate in the presence of anhydrous halide salts.

ing temperature is n-hexyl alcohol, ra-hexyl ether, n-Bu3P, internal standard, and n-BusPO.1,2-Dioxane was prepared by the method of Criegee8 in 18% yield. The product had bp 49°(67 mm) [lit.9 bp 61-62°(110 mm)]; n20D 1.4261 (lit.7 1.4262). Ir, mass, and nmr spectra confirm the structure.1,4-Butanediol was trapped from the glc effluent of a reduced sample of 1,2-dioxane for comparison with an authentic sample.The best column for quantitative glc analysis of the components of a reduced sample of 1,2-dioxane was a 10 ft X 0.25 in. Carbowax 20M (16.7%) on AW Chromosorb P (60-80 mesh); 2-dodecanone was used as internal standard.Di-ierf-butyl peroxide was obtained from Lucidol and was 99.9% pure by glc.Ascaridole was obtained from K & K. The reduction product, p-menthene-1,4-diol, was prepared by hydride reduction. Ascaridole (1.7 g, 1.01 X 10~1 2 mol) in 30 ml of benzene was refluxed with NaAlH2(OCH2CH2OCH3)2 (2.86 X 10~2 mol) for 2 hr. On cooling, 50 ml of water was added, benzene was removed on a Rotavapor, and the aqueous phase was

36) For ease of comparison, we refer here to compounds derived from both 4 and 23 using the same numbering of the sugar protons and considering both as ribofuranosyl derivatives. (37) S. Hanessian and A. G.