Derivatives of Monoacetone Xylose

Hydroxy group interactions in stannylated carbohydrates. Structures and thermal stabilities of 5-deoxy-5-C-(Ph3Sn)-1,2-O-isopropylidene-α-D-xylofuranose, 5-deoxy-5-C-(IPh2Sn)-1,2-O-isopropylidene-α-D- and -L-xylofuranose, and 5-deoxy-5-C-(I2PhSn)-1,2-O-isopropylidene-α-D- and -L-xylofuranose

“…Selected bond lengths and angles for ()-3, and also those for ()-3, largely as previously reported, 6 are listed in Table 3. The C-Sn-C bond angles at tin are close to tetrahedral, being in the ranges 106.8(4) to 113.8(4)Њ for ()-3, and 106.55 (8) to 114.27(8)Њ for ()-3. However, in each molecule there is also a Sn ring-oxygen (O4) separation of 3.262(8) and 3.2520 (14) Å in ()-3 and ()-3, respectively, well within the sum of the van der Waals radii of 3.70 Å.…”

C-nucleoside studies. Part 12. Synthesis of 3-α- and 3-β-(D-xylofuranosyl)pyrazoles

“…119--121 "C, [a], -36.6" (c 1.9 in CHC1,); vnUl, (KBr) 3 390 (OH), 3 240 ( X H ) , 2 110 (CfC), and 1 385 and 1 375 c1ii-l (both CMe,) ; 6 ( 100 13). -A solution of the pyrazole (12) (5.5 g) in dry acetone (275 ml) containing concentrated sulphuric acid (2.75 nil) was left for 7 h, when t.1.c. of a neutralized sample showed the presence of a major new product.…”

“…The lactone was converted into its di-0-isopropylidene derivative (10) in very high yield by a modification of the literature procedure.8 It is well established that the reaction of organolithium reagents with lactones in equimolar amounts gives the lactol as the major product; when the lactone (10) was allowed to react with lithium acetylide in tetrahydrofuran (THF) at low temperatures,l0 the acetylenic lactol (11) was obtained in 72% yield after chromatography. When the lactol (11) was heated under reflux with hydrazine hydrate in ethanol,' the crystalline pyrazole (12) was produced in SS:/, yield, and when a solution of this material in acetone containing sulphuric acid was left for several hours, clean isomerisation occurred to give the 2,3:4,5-0-isopropylidene derivative (13). This isomerisation reflects the greater stability of isomer (13) in which the central dioxolan ring has the two bulky substituents in a trans-arrangement and parallels our earlier findings in an isomeric series.'…”

Synthesis of 9-β-D-Arabinofuranosylguanine*

“…The nucleoside spots were located by visual examination under ultraviolet light. (Levene and Raymond, 1933) in 200 ml of glacial acetic acid and 23 ml of acetic anhydride was added 14 ml of concentrated sulfuric acid dropwise with stirring and sufficient cooling to maintain a temperature of about 20°. After the addition was complete, the reaction was left at room temperature for 18 hours, and was then poured into about 500 ml of ice water slowly and with stirring.…”