L-Gulose

Guinea worms Guimer-Preston zones Guinier radius L-Gulose [6027-89-0]... 

Most substrates, with the exception of hydroxypymvate, have a threo configuration of hydroxyl groups at the C-3 and C-4 positions (139). The new stereocenter formed in TK-catalyzed addition is formed in the threo configuration with high diastereo-selectivity (151). Using TK-catalyzed condensations of hydroxypymvic acid with a number of aldehydes a practical preparative synthesis of L-idose [5934-56-5], L-gulose [6027-89-0], 2-deoxy-L-xylohexose, and... 

There is another sugar, (-l-)-gulose, that gives the same aldaric acid on oxidation as does (-l-)-glucose. 

Problem 25.18 I Reduction of L-gulose with NaBH4 leads to the same alditol (D-glucitol) as reduction of D-glucose. Explain. 

Problem 25.22 What aldopentose would give a mixture of L-gulose and L-idose on Kiliani-Fischer chain extension ... 

Before 1983, branched-chain sugars had not been found in bacterial polysaccharides, but there are now five examples belonging to this class. The LPS from Coxiella burned phase I contains both 6-deoxy-3-C-methyl-L-gulose (L-virenose) as pyranoside (12) and 3-C-(hydroxymethyl)-L-lyxose as furan-oside (13). Another 6-deoxy-3-C-methylhexose, having the manno configuration, is a component of the Nitrobacter hamburgiensis 0-antigen. ... 

Both L-gulose12,13 (9) and D-gulose (d-9, see Ref. 10) have been oxidized with bromine to L- or D-gulonic acid, respectively (see Scheme 1). L-Gulose (9) has been prepared by a number of different procedures. Schemes 2 and 3 show two early procedures that afforded L-gu-lose, but the overall yields were low (<30%). In the first procedure12 (see Scheme 2), D-glucitol (10) was converted into 2,4-O-benzylidene-D-glucitol (11), which was then oxidized with lead tetraacetate to 2,4-O-benzylidene-L-xylose (12). Nitromethane was added to 12 to afford crystalline 13 in 50% yield. Hydrolysis of 13 provided 14, which was treated with sodium hydroxide, followed by sulfuric acid, to afford 9, which was isolated in 52% yield as the 2-benzyl-2-phenylhydrazone. 

In the second procedure13 (see Scheme 3), D-glucitol (10) was converted into 5-O-benzoyl-1,3 2,4-di-O-ethyl idene-6-O-trityl-D-glucitol (17) by successive treatment with acetaldehyde to produce 15, with chlorotriphenylmethane to provide 16, and with benzoyl chloride to afford 17. Selective removal of the trityl protecting group from 17, to give 18, followed by oxidation of 18, provided 19 which, on hydrolysis, afforded L-gulose (9). 

The conversion of D-mannose (20) into L-gulose (9) was reported by Evans and Parrish,15 and is shown in Scheme 4. D-Mannose (20) was converted into 21 by condensation with acetone, methanol, and 2,2-di-methoxypropane in the presence of an acid, and mild hydrolysis of 21 afforded 22. Methanesulfonylation of 22 provided 23, which was transformed into 24 with sodium acetate in refluxing N,N-dimethyl-formamide. The overall yield of 24 from D-mannose was >50%. Base hydrolysis, followed by acid hydrolysis, afforded L-gulose (9). 

Minster and Hecht16 reported a synthesis of a derivative of L-gulose (9) from D-glucose (25) that takes advantage of the ready availability of... 

A variety of methods has been developed for the reduction of the gulonolactones and derivatives to D- and L-gulose and the corresponding derivatives. D-Gulono-1,4-lactone (2) was reduced to D-gulose (d-... 

A relatively short route has been presented to convert o-glucono-1,5-lactone (1) into L-xylose and L-gulose [94] (Scheme 21). Acetalization of 1 gave 71, the... 

L-Gulose readily forms an anhydride, and in a study on alginic acid, methylated L-guloses were isolated as their anhydrides.88 Other anhydro sugars, such as 3,6-anhydro-L-galactose and its 2-methyl ether, may be found in algae (see, for example, Ref. 412), and, under certain circumstances, 2,3,6-tri-O-methyl-D-galactose may form an anhydride.571... 

Condensation of the mixture of dienes 661 and 662 with 2(R)-menthyl glyoxylate (until only the trams,trams diene had entered into reaction) gave1153 a mixture of three products (667-669) in 63% overall yield. This mixture was separated into its components. Reduction of R1 to a hydroxymethyl group in 667 and 668, and m-hydroxylation of the double bond, gave disaccharides 670 and 671, in which the newly created sugar units were identified as D- and L-gulose, respectively. 

Problem 22.27 Fischer prepared L-gulose by oxidizing o-glucose to two separable lactones of glucaric acid. These were reduced to lactones of gluconic acid, which were further reduced. Give all the structures in these... 

In previous syntheses the gulose subunit started with the very rare L-gulose. The procedure described here begins with D-mannose, in which the C1-C4 stereochemistry is correct, and incorporates an inversion at C5 to obtain the desired gulose. Selective equatorial... 

Compound 43 has been prepared from a mixture of L-gulose and L-sorbose, or from L-gulose.293-296 The mixture of L-gulose and L-sorbose... 

Several miscellaneous procedures have been reported for the preparation of L-gulonic acid (47). 5-0-Benzoyl-l,3 2,4-di-0-ethylidene-D-glucitol (72) was oxidized388 with chromium trioxide to 73. After hydrolysis of 73, the L-gulose (45) formed was oxidized369,370 with bromine to 21. As noted in Section III,5b, 3,5 4,6-di-0-ethylidene-L-gu-lonic acid (50) was prepared from 3,5 4,6-di-0-ethylidene-D-gulitol (49) in 50-70% yield. By hydrolysis, 50 afforded333 21. 

L-Gulose yields the same aldaric acid on oxidation as does D-glucose. 

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