6-Deoxy-L-ascorbic acid

Acetamido-2-deoxy-D-glucose is a component of a mucopolysaccharide hyaluronic acid. It has been demonstrated, by PET imaging with the corresponding F labeled compound, that this glucose derivative is incorporated into the connective tissue at the interface of a tumor and healthy tissue. Thus, it can be used as a tumor label. 6-[ F]-6-Deoxy-L-ascorbic acid also deserves attention, as it maintains the antioxidant properties of ascorbic acid. Thus, it can be useful to smdy the biochemical... 

Figure 6.19 Preparation of sugars labeled with F 2-[ F]-2-deoxytalose, N-[ F]-fluoroacetyl-D-glucosamine, and 6-fluoro-6-deoxy-L-ascorbic acid.

A reaction, that does not involve the enediol takes place on halogenation. Treatment of 138 with hydrogen bromide-acetic acid affords 5-0-acetyl-6-bromo-6-deoxy-L-ascorbic acid (166).360 Compound 166 was used for the synthesis of 6-substituted derivatives of 138, via the 5,6-anhydro derivative.361... 

C6H805 6-deoxy-L-ascorbic acid 528-81-4 25.00 1.2816 2 7732 C6H10N2O2 DL-5-ethyl-5-methyl-2,4-imidazolidinedione 16820-12-5 25.00 1.1318 2... 

Conversion into Pyrazine Derivatives. Pyrazine derivatives are examples of 1,2-diazines in the carbohydrate series (24), The derivative was prepared by partial tosylation of 41 to give the mono-p-toluene-sulfonyl derivative (60), which upon treatment with sodium iodide in acetone gave the bicyclic diazine derivative (62). However, the di-p-toluenesulfonyl derivative (61) afforded, under conditions similar to those specified, the 6-deoxy-6-iodo 63. The 6-bromodeoxy 64 was prepared (54) by reacting phenylhydrazine with 6-bromo-6-deoxy-L-ascorbic acid. 

Eromo-6-deoxy-L-ascorbic acid D-6r]/ /iro-Hex-2-enonic acid y-lactone (n-isoascorbic acid)... 

Some 6-amino-6-deoxy-L-ascorbic acid derivatives have been synthesized and their cytotoxic properties evaluated, " and ( ) 4-amino-4-deoxy-ascorbic acid has been prepared. Michael-like reactions between L-ascorbic acid and some nitrostyrenes have led to adducts such as 39. ... 

Bromo-6-deoxy-L-ascorbic acid (480 mg per kg body weight) was capable of lowering the toxicity of 10 mg cisplatin per kg mouse (Sverko et al. 1999). In mice treated wilii higher doses of cisplatin (15 mg per kg body weight) 6-bromo-6-deoxy-L-ascorbic acid acerbated the toxic effects of cisplatin. 

Plants synthesise ascorbic acid from the active form of d-mannose, which is GDP-D-mannose. In mammals, the starting compound is UDP-D-glucose. Microorganisms and higher fungi synthesise 6-deoxy-L-ascorbic acid from L-fucose and D-erythroascorbic acid from D-arabinose. 

Sodium ascorbate and ascorbic acid esters, such as ascorbyl 6-palmitate (5-111) and ascorbyl 2-phosphate (5-113), are fully bioavailable, while ascorbyl 2-sulfate (5-114) is a completely inactive vitamin form. Phosphate and sulfate are about 20 times more stable to oxidation than the free acid. D-lsoascorbic acid (5-107) shows only 5-20% activity, 6-deoxy-L-ascorbic acid (5-115), found in fungi, has about 30% activity and the bound ascorbic acid form ascorbigen has 15-20% of the activity of ascorbic acid. Ascorbic acid 2-0-P-D-glucoside, systematic name 2-0-(P-D-glucopyranosyl)-L-ascorbic acid (5-116), has the same biological activity as ascorbic acid and is also stable against oxidation. 

Deoxy-6-fluoro-L-ascorbic acid ° (314) was prepared from methyl 2,3-<9-isopropylidene-6-0-tosyl-a-L-gulosonate (313) by reaction with KP followed by isomerization of the product (with H" " cation-exchange resin). 

CgHyClOs 0.5 CH3N02r 6-Deoxy-6-chloro-L-ascorbic acid nitromeo-thane solvate, 46B, 304 C6H7O3, a,7-Dimethyltetronic acid, 34B, 172... 

Figure 6 Formation of L-scorbamic acid and red pigment, 2,2 -nitriiodi-2(,2 )-deoxy-L-ascorbic acid mono-ammonium salt (NDA) >...

F. Yamamoto, S. Sasaki, M. Maeda, Positron labeled antioxidants Synthesis and tissue biodistribution of 6-deoxy-6-[ F]fluoro-L-ascorbic acid, Appl. Radiat. Isot. 43 (1992) 633-639. 

New derivatives of L-ascorbic acid have been synthesized including saccharoascorbic acid, 5-ketoascorbic acid, 2-phosphoric-ascorbic acid, 6-bromo-6-deoxyascorbic acid, 6-chloro-6-deoxyascorbic acid, the 5,6-dehydro-5,6-dideoxy derivative, the 4,5-dehydro-5-deoxy derivative, the 5,6-dideoxy derivative, and numerous nitrogen derivatives. 

Those derivatives of L-ascorbic acid in which one or more of the hydroxy-groups on C-2, C-3, C-5, or C-6 are missing are described as deoxy compounds. The lack of stability of vitamin C has, understandably, fuelled interest in analogues of the molecule which, possibly by virtue of their deoxy structures, may show enhanced stability whilst... 

Tetroses and Pentoses - 4-0- -Butyldimethylsilyl-2,3-0-isopropylidene-L-threose (1) has been prepared in seven efficient steps from o-xylose. 3,4-0-Isopropylidene-D-eythrulose (4) has been synthesized from the known tetritol derivative 2 by primary protection as the silyl ether 3, followed by Dess-Martin oxidation and desilylation. Compound 2 was derived from D-isoascorbic acid (see Vol. 22, p. 178, refs. 9,10). In a similar reaction sequence, the enantiomer 5 has been obtained from L-ascorbic acid. The dehomologation of several di-0-isopropylidenehexofuranoses e.g., 6- 7) has been carried out in two steps without intermediate purification, by successive treatment with periodic acid in ethyl acetate, followed by sodium borohydride in ethanol. Selective reduction of 3-deoxy-D-g/jcero-pentos-2-ulose (8) to 3-deoxy-D-g/> cero-pent-2-ose (9) has been achieved enzymically with aldose reductase and NADPH." 4-Isopropyl-2-oxazolin-5-one (10) is a masked formaldehyde equivalent that is easily converted to an anion and demasked by mild acid hydrolysis. One of the three examples of its use in the synthesis of monosaccharides is shown in Scheme 1. ... 

The 6-bromo- and 6-chloro-6-deoxy-derivatives of L-ascorbic acid can be made directly by reaction with hydrogen bromide or hydrogen chloride in... 

Acid Derivatives. — D-Arabinono-7-lactone, 2,3-di-0-acetyl-2-C-methylery-throno-1,4-lactone, a 1 1 complex of L-serine and L-ascorbic acid, and methyl 4-C-acetyl-6-deoxy-2,3-0-methylene-D-galactonate. ... 

The formation of 5-hydroxymethylfuran-2-carbaldehyde from saccharose proceeds via hydrolysis to fructofuranosyl cation and glucose (Figure 4.26). Ehmination of a proton and two molecules of water from the fructofuranosyl cation yields 5-hydroxymethylfuran-2-carbaldehyde. Under dry pyrolytic conditions and at temperatures above 250 °C, 90% of 5-hydroxymethylfuran-2-carbaldehyde originates from the fructose moiety and only 10% originates from glucose. Pentoses and L-ascorbic acid dehydrate in the same way as hexoses under addic conditions yielding furan-2-carbaldehyde (via reactive 3-deoxy-L-t/jreo-pentos-2-ulose and 3,4-dideoxypentosulos-3-ene) as the main product (see Section 5.14.6.1.5). 6-Deoxyhexoses, such as L-rhamnose, yield, analogously, 5-methylfuran-2-carbaldehyde (4-195). 

In the course of work leading to substituted triazoles, dehydro-L-ascorbic acid 3-oxime 2-phenylhydrazone was converted to its 5-0-aoetyl-6-bromo-6-deoxy-derivative (22). 

Retrosynthetic analysis demonstrated the need for a 1,2,3-butanetriol and a 1,2,3,4-butanetetrol with 2R, 3S chirality, which corresponds to that found in 2-deoxy-D-ribose. Our initial involvement with L-ascorbic acid (vide infra) led us to examine an equally accessible diastereomer, D-isoascorbic acid. While the former has been extensively studied, the same is not true for the latter. This could be due to early difficulties encountered in the preparation of 5,6-(9-protected derivatives. Unlike their counterparts from L-ascorbic acid, which are equally accessible from / -tartrates, chirons derived from D-isoascorbic acid are not easily obtained from other natural sources. They can be available from w. y( -tartrates only when differentiation between the two carboxyl groups is feasible. 

Ascorbic acid, dehydroascorbic acid, dlketogluconic acid, and glucose have been determined down to nanogram levels by h.p.l.c. on a hydrophilic, polyvinylalcohol gel, post-column derivatization with benzamldine, and fluorlmetric detection. The method was applied to ascorbic acid in fruit Juice.Ascorbic acid, its 2-sulphate, 2-phosphate, 2-0-methyl, and 6-bromo-6-deoxy derivatives, and a related non-enzymic browning product, 5-methyl-3,4-dihydroxy-... 

The structure of the osazone derived from dehydroascorbic acid remains in dispute. Recently (Vol. 13, p. 95) it was described as the phenylhydrazine-phenylazo-structure (34), but it is now claimed that the bis(hydrazone) formula (35) fits the n.m.r. and u.v. data more satisfactorily. The structure of the bi-cyclic oxidation product of (35) has been shown to be a 3,6-anhydride (36) by n.m.r. and m.s. A n.m.r. study of the formation of dehydroascorbic acid hydrazones revealed that the two 2-phenylhydrazides (37) were formed initially and subsequently underwent dehydration to give the two rotationally isomeric 2-phenyIhydrazones. Reaction of 6-bromo-6-deoxy-isoascorbic acid (D-ery thro) with phenyl hydrazine afforded the cyclized bis(hydrazone) (38). Treatment of D-threo-ascorbic acid bis(phenylhydrazone) with caustic soda afforded the cyclized product (39). The corresponding D-erythro- and L-threo-isomers were also prepared and the side-chains have been modified in various ways. 

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