Furanose derivative

The discrepancy between the behavior of arabinose- and xylose-3, 5-(hydrogen phosphates) probably reflects the difference which exists in the steric arrangement of these two cyclic phosphodiesters. In the xylo-furanose derivative (89), the hydroxyl group on C-3 and the primary hydroxyl group are cis the cyclic phosphate is easily formed and perfectly strainless. In arabinofuranose these same groups are in position trans and, although an apparently strainless molecule can be constructed from models, it is probable that in this case the main ring of the compound will be that formed by the phosphodiester, with a concomitant tendency for the compound to assume the aldehydo form. Objection to... 

While the above studies were in progress results from dioxane derivatives were published (19,94) which support all of the comments and cautions we have made above. Additional reports have been made of a long-range coupling across a ring oxygen in an unsaturated pentopy-ranose derivative (17) and in a saturated furanose derivative (20). 

Ionophoresis of Carbohydrates. Part II. Some Pyranose and Furanose Derivatives of D-Glucose, ... 

Qualitative relaxation-studies have also been reported for an extensive series of derivatives of inositols, pentopyranoses, l,6-anhydro-/3-D-hexopyranoses, furanoses, and septanoses. In all instances, the experimentally determined Ri(ns) values reflect the anticipated geometry. For the furanose derivatives especially, they provide a better means for distinguishing between epimeric pairs than the relatively ambiguous interpretation of coupling-constant data. 

A number of derivatives of D-glucuronic acid have been made by Goebel and Babers37 with a view to their use in the synthesis of aldobionic acids. With the same object Owen, Peat and Jones38 prepared both pyranose and furanose derivatives of D-glucurone. 

Tributyl tin radical mediated cyclization of the glucose derived exo-methylene furanose derivatives led to highly functionalized cA-fused bicyclic ethers. The product could subsequently be transformed into optically active tricyclic nucleoside analogue or oxepine derivative (Fig. 51).67... 

D-glucose and its lactone from 2,3,6-trimethyl-D-glucose provided conclusive proof that the ring system was not of the hexylene oxide type.142 188 The final evidence necessary to characterize the tetramethylglucose in question as a furanose derivative was provided by Haworth, Hirst and Miller,176 who demonstrated that oxidation of the tetramethylglucose with bromine water and of the resulting lactone with nitric acid yielded dimethoxysuccinic acid and oxalic acid, but not i-zyZo-trimethoxyglutaric acid, the absence of which ruled out a pyranose structure. 

When the benzoylated lactone 172a was debenzoylated with sodium methoxide and the product boiled in 1,4-dioxane, the more-stable 1,4-lactone 175 was isolated upon rebenzoylation. Reduction of the lactone carbonyl group afforded (220) the crystalline furanose derivative (176) of ascarylose. A similar procedure, performed on the benzoylated 3-deoxy-D-arabino-hexono-1,5-lactone 170, gave (221) the 3-deoxy-D-oraWno-hexo-furanose derivative. 

H- and F-N.m.r. Data for Difluorinated Anhydrohexo-pyranose and -furanose Derivatives... 

Even if the anomeric hydroxyl group is the most reactive, the presence of five nucleophilic hydroxyl groups in these substrates can lead to the formation of various mono- and polyethers. Moreover, these ethers can be pyranose or furanose derivatives with linear and branched octadienyl tethers (Fig. 9). 

In a number of reactions on furanose derivatives, steric restraints interfere with anhydro-ring formation. 6-Deoxy-2,3-0-isopropylidene-5-O-tosyl-L-mannofuranose is readily converted by sodium methoxide into methyl 6-deoxy-2,3-0-isopropylidene-/3-D-allofuranoside. In this... 

The reaction was also studied with acetylated and benzoylated pyranose and furanose derivatives of D-galactose,18 D-mannose,19 D-lyxose,20 L-rhamnose,10 D-ribose, D-xylose, and L-arabinose,21 and with some partially benzoylated D-glucoses.22... 

In the furanose forms, the four carbon atoms involved in the ring are numbered 1 to 4, starting with the anomeric carbon atom.3,22 The symbol D or L now distinguishes between the two furanoses derived from one apiose, the respective symbol referring to the reference (highest-numbered), asymmetric carbon atom (C-3) of the cyclic forms, as depicted in formulas 2 and 3. After cyclization, the ring-... 

Scheme 12.—Chemical Synthesis of the Furanose Derivative of N-Acetyl-D-mannosamine.

A convenient synthesis of ascarylose in four steps starting from L-rhamnono-1,5-lactone (121) was reported.202 The deoxy group in C-3 was introduced through stereoselective hydrogenation of the 2-enonolactone 122 as reported for the preparation of 3-deoxy sugars (see Section III.2). A crystalline furanose derivative of ascarylose, 2,5-di-(3-benzoyl-3,6-dideoxy-a-L-arafo>m-hexofura-nose (125) was also obtained (Scheme 35).203... 

O. Varela, A. Fernandez Cirelli, and R. M. de Lederkremer, A crystalline furanose derivative of ascarylose. Synthesis of 2,5-di-0-benzoyl-3,6-dideoxy-a-L-arah/no-hexofuranose, Carbohydr. Res., 83 (1980) 130-135. 

A similar rearrangement has been performed on furanosic derivatives, by a Sn2 displacement of a triflate protecting group at C-5, using sodium trifluoroacetate.173 Thus, 1,2-0-isopropylidene-/l-L-idofuranurono-6,3-lactone (59) has been prepared from 1,2-O-isopropylidene-a-D-glucofuranu-rono-6,3-lactone (40). 

Furanose derivatives of Kdg and their 3-bromo and 3-deuterio analogues, were also prepared from D-glucono-1,5-lactone319 via the 2-enonolactone.98... 

C. Di Nardo and O. Varela, Synthesis of furanose derivatives of 3-deoxy-D-erythro-2-hexulosonic acid and their 3-bromo and 3-deuterio analogs, Carbohydr. Res., 328 (2000) 605-610. 

Rofecoxib, a furanose derivative, is a potent, selective COX-2 inhibitor (Table 36-1). In the USA, rofecoxib is approved for osteoarthritis and rheumatoid arthritis, and it also appears to be analgesic and antipyretic—in common with other NSAIDs. This drug does not inhibit platelet aggregation and appears to have little effect on gastric mucosal prostaglandins or lower gastrointestinal tract permeability. At high doses it is associated with occasional edema and hypertension. Other toxicities are similar to those of other coxibs. 

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