2,5-dideoxy-2,5-diiodo

Unless otherwise noted, acetone was the solvent. 6 Yield of monodeoxy-monoiodo-alditol derivative. Yield of dideoxy-diiodo-alditol derivative. d Yield of sodium sulfonate. Free iodine liberated. i Acetonylacetone. Plus sodium bicarbonate to prevent cleavage of the benzylidene group. Acetic anhydride. 

A crystalline 5,5 -diene, or bis (vinyl ether), derivative of sucrose has been prepared from 6,6 -dideoxy- 6,6 -diiodo-sucrose hexa-acetate, derived from the 6,6 -ditosylate, by treatment with silver fluoride in pyridine (26). 

Anhydro-a-D-fructofuranose 3,6-anhydro-P-D-fructofuranose 1,2 2,l -dianhydride (64) 6-Azido-6-deoxy-a-D-fructofuranose 6-deoxy-P-D-t/ reo-hex-5-enofuranose 1,2 2,1 -dianhydride" (65) 6-5-Heptyl-6-thio-a-D-fructofuranose 6-deoxy-p-D-tft eo-hex-5-enofuranose 1,2 2,l -dianhydride" (66) 4,5 4, 5 -Di-0-isopropylidene-di-p-D-fructopyranose 1,2 2,l -dianhydride (67) 6,6 -Dideoxy-6,6 -diiodo-di-p-D-fructofuranose 1,2 2,1 -dianhydride (68)... 

H n.m.r.spectrum of compound 64 showed the well-known allylic coupling 111 between the protons on C-4 and C-6 and C-4 and C-6. On reacting with silver fluoride and pyridine, 2,3,4,l, 3, 4 -hexa-0-acetyl-6,6 -dibromo-6,6 -dideoxysucrose, like the 6,6 -diiodo derivative (63), gave the corresponding 6,6 -dideoxy-5,5 -diene derivative.96... 

The first of these methods involves the reaction of triphenyl phosphite methiodide with methyl 3-0-methyl-2-0-p-tolylsulfonyl-a-D-glucopyrano-side, hydrogenation of the resulting 4,6-diiodo derivative, and hydrolysis,186 as adapted to monosaccharides by Kochetkov and coworkers.1,0 In another approach,281 ethyl 2,3-anhydro-4,6-dideoxy-D-nbo-hexopyranoside, obtained from desosamine, was treated with sodium methoxide, to give a mixture of 2- and 3-methyl ethers. After fractionation and separation of side products,288 the 3-methyl ether was hydrolyzed, to give crystalline chalcose. McNally and Overend800 have described another synthesis, starting from methyl 4-deoxy-D-xj/Zo-hexoside.107... 

Prior to 1932, a year of some significance in this field (see p. 191), the reaction was, for example, applied to the preparation of methyl 2,3,4-tri-0-acetyl-6-deoxy-6-iodo-a-D-glucoside348 (25 hours at 130°), 2,3,4,2, -3, 4 -hexa-0-acetyl-6,6 -dideoxy-6,6 -diiodo-trehalose347 (24 hours at 130° 89% yield), and methyl 2,3,4,2, 3 -penta-0-acetyl-6,6 -dideoxy-6,6,diiodo-/3-cellobioside348 (60 hours at 100° 94% yield of product 100% yield of sodium p-toluenesulfonate). Such products are valuable in the preparation of other co-derivatives, e.g., co-deoxy sugars (see p. 157). 

In contrast, the 6-tosyloxy group of l,6-di-0-tosylketohexofuranose derivatives is more readily replaced by iodine. Thus, by reaction during 24 hours at 90-100°, 2,3-0-isopropylidene-l,6-di-0-tosyl-L-sorbose gives264 the corresponding 6-deoxy-6-iodo-l-0-tosyl derivative (possibly accompanied by some unisolated l,6-dideoxy-l,6-diiodo derivative) and 2,3-0-isopropylidene-l,6-di-0-tosyl-D-fructose behaves266 similarly (16 hours at 100°). 

Further applications of the reagent with nuclesosides have been examined.170 An interesting observation in the iodination of S -O-tritylthymidine was that a small amount of the 3, 5 -dideoxy-3, 5 -diiodo species was obtained in addition to the expected preponderance of the C-3 iodinated product. Presumably, HI produced during the course of the reaction effected the removal of the acid-sensitive trityl ether. 

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