A-D-Mannofuranose

Fig. 3.—A. Initial Slope Approximation to Determine the Initial, Nonselective, Spin-Lattice Relaxation Rate of H-S of 2,3 S,6-Di-0-isopropylidene-a-D-mannofuranose (2) in Me2SO-d Solution. (Points between 0.01 and l.SS s were selected for tracing the best straight line.) B. The Same as in A for H-1 of a Partially Deuterated Sample of 1,6-Anhydro- -cellobiose Hexaacetate (3). [Note that the relaxation of H-1 is strongly dependent on the choice of I value. An R (ns) value of 0.24s was obtained from the data points 0 t 5s, where a value of 0.18 s was obtained from the terminal decay 5 lOs (see text).]...

For 2,3 5,6-di-O-isopropylidene-a-D-mannofuranose (183), separation of the anomeric products (184 and 185) was possible,135 and their structures were elucidated by periodate-oxidation studies. The configurational assignment for these products was based on the greater value of the specific rotation for the a anomer, as compared with that of the j3 anomer. The higher chromatographic mobility of one of the... 

Variable-temperature 13C NMR spin-lattice relaxation time measurements have been used to probe the motional behavior of 2,3 5,6-di-O-isopropylidene-a-D-mannofuranose (22) in dimethyl sulfoxide solution.67 This carbohydrate deriva-... 

Examples of sugar homologation based on the use of 2-lithio-l,3-dithiane (2-LDT, 13) are surprisingly rare relative to the popularity of this reagent [25]. Stereoselective chain extension of a partially protected hexose, 2,3 5,6-di-0-isopropylidene-a-D-mannofuranose (14), into a D-g/ycero-D-gatocfo-heptose derivative (16) was reported by Paulsen and his coworkers several years ago [26] (Scheme 5). 

HS03)2-2,6Mana-2Glca-1 -sn-2, >-O-alkylglycerol [C-specific] [PtMe3L]BF4, L = a-D-mannofuranose or > HC, Arc.OH 340... 

Mannojirimycin (1) and 1-deoxymannojirimycin (2) were prepared from 2,3 5,6-di-0-isopropylidene-a-D-mannofuranose (26) (Scheme 5). The oxime 27, prepared from 26, underwent reduction by hydrogenation in the presence of Raney nickel, and subsequent removal of the trityl group afforded the amines 28 and 29. Acid hydrolysis of 28 afforded 30 (21%), which was converted to 31 (28%) that upon treatment with Dowex 1 (OH ) resin afforded 1. On the other hand, hydrogenation of 28 gave 32, which upon removal of the... 

Synthesis from o-mannose A total synthesis of D-(- -)-biotin (1) from D-mannose has also been reported (Scheme Treatment of 2,3 5,6-di-0-isopropylidene-a-D-mannofuranose (17) with benzoyl chloride followed by selective hydrolysis of the terminal acetal group afforded 1-0-benzoyl-2,3-0-isopropylidene-a-D-mannofuranose (18). Subsequent periodate oxidation and chain extension with the proper phosphorane followed by hydrogenation gave the uronate derivative 19. Treatment of 19 with NaOCHs followed by reduction of the resulting aldehyde with sodium borohydride afforded compound 20. 

The condensation of D-mannose with cyclohexanone in the presence of sulfuric acid yields 2,3 5,6-di-0-cyclohexylidene-a-D-mannofuranose, as reported by Guthrie and Honeyman. ... 

Periodate oxidation of l-0-benzoyl-2,3-0-isopropylidene-a-D-mannofuranose has afforded access to several derivatives of D-lyxuronic acid, and glyco-furanosyl halides of D-riburonic acid, which are of value in nucleoside synthesis, have been made by way of the corresponding thiofuranosides (see Chapter 7). 

Formation of a glycosyl fluoride from a hemiacetal fluorination of 2,3 5,6-di-0-isopropylidene-a-D-mannofuranose by treatment with DAST [24]. 

Penta-Ac 1,2,3,5,6-Penta-0-acetyl-4-thio-a-D-mannofuranose C16H22O10S 406.41 [a]o +148 (c, 0.14 in CHCI3). 

Benzoyl-2,3-0-isopropyUdene-a-D-mannofuranose, 1-71 6-0-Benzoyl-l,2-0-isopropyUdene-5-0-mesyl-3-0-methyl-a-D-... 

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