2,3:5,6-Di-0-isopropylidene-a-D-mannofuranose

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). 

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. 

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]. 

Di- O -isopropylidene- p-D-idofuranose, 1-69 1,2 3,5-Di- O -isopropylidene- p-L-idofuranose, 1-69 1,2 5,6-Di- O -isopropylidene- p-L-idofuranose, 1-69 1,2 3,4-Di- O -isopropylidene- p-L-idoseptanose, I-10 1,2 4,5-Di- O -isopropylidene- p-L-idoseptanose, I-10 1,2 5,6-Di- O -isopropy lidene-L-c/ >o -inositol, 1-28 l,2 4,5-Di-0-isopropylidene-mMco-inositol, 1-31 1,2 3,4-Di- O -isopropy lidene-myo -inositol, 1-32 1,2 4,5-Di- O -isopropy lidene-myo -inositol, 1-32 1,2 5,6-Di- O -isopropy lidene-myo -inositol, 1-32 l,2 3,4-Di-0-isopropylidene-D-mannitol, M-25 l,2 3,6-Di-0-isopropylidene-D-mannitol, M-25 l,2 4,5-Di-0-isopropylidene-D-mannitol, M-25 l,2 4,6-Di-0-isopropylidene-D-mannitol, M-25 l,2 5,6-Di-0-isopropylidene-D-mannitol, M-25 2,3 4,5-Di-0-isopropylidene-D-mannitol, M-25 2,4 3,5-Di-0-isopropylidene-D-mannitol, M-25 l,2 5,6-Di-0-isopropylidene-L-mannitol, M-25 2,3 5,6-Di-0-isopropylidene-a-D-mannofuranose, 1-71 2,3 5,6-Di-0-isopropylidene-a-L-niannofiiranose, 1-71 2,3 5,6-Di-(9-isopropylidene-a-D-niannofuranosyl bromide, M-26 2,3 5,6-Di-O-isopropylidene-a-D-mannofuranosyl chloride, M-27 2,3 5,6-Di-O-isopropylidene-p-D-mannofuranosyl chloride, M-27 2,3 5,6-Di-O-isopropylidene-a-D-mannofuranosyl 2,3 5,6-di-0-isopropylidene-a-D-mannofuranoside, M-30 2,3 5,6-Di-O-isopropylidene-p-D-mannofuranosyl 2,3 5,6-di-0-isopropylidene-a-D-mannofuranoside, M-31 2,3 5,6-Di-0-isopropylidene-a-D-mannofuranosyl iodide, M-29 2,3 5,6-Di-0-isopropylidene-p-D-mannofuranosyl 2,3,5,6-tetra-O-acetyl-a-D-mannofuranoside, M-31... 

Di-0-benzoyl-4,6-di-0-methyl-(3-D-mannopyranosyl fluoride, M-43 2,3 5,6-Di-0-cyclohexylidene-a-D-mannofuranose, M-114 2,3 4,6-Di-0-cyclohexylidene-a-D-mannopyranosyl chloride, M-42 2,3 5,6-Di-0 -isopropylidene-a-D-mannofuranose, 1-71 2,3 5,6-Di-0-isopropylidene-a-L-mannofuranose, 1-71 2,3 5,6-Di-0-isopropylidene-a-D-mannofuranosyl bromide, M-26 2,3 5,6-Di-0-isopropylidene-a-D-mannofuranosyl chloride, M-27... 

Silver carbonate on Celite in methanol causes the oxidation of 3,4,6-tri-, 3,4-di-, and 3-O-methyl-D-fructose to the corresponding ethers of D-arabinonic acid. The 1,4,6-, 1,4,5-, and 1-ethers cleave at C-2—C-3, whereas the 1,3,4,6-and 1,3,4-substituted compounds are resistant to reaction under these conditions. A suitable method for oxidizing 2,3 5,6-di-0-isopropylidene-a-D-mannofuranose and jS-D-allofuranose to the corresponding lactones involves... 

The synthesis of the 2,5-disubstituted pyrrolidine 43 from D-mannitol by standard chemistry and the synthesis of pyrrolidines 44 by addition of azomethine ylides to vinylene carbonate " as well as the synthesis of the imino-heptitol 45 from 2,3 5,6-di-0-isopropylidene-a-D-mannofuranose have been reported. 

The reaction of reducing monosaccharides (e.g. 2,3 5,6-di-0-isopropylidene-a-D-mannofuranose) with an equimolar mixture of phthalimide, dialkyl azodi-carboxylate, and triphenylphosphine yielded both anomeric iV-glycosylphthali-mides, whereas A/ -glycosyl-l,2-dialkoxycarbonylhydrazines [e.g. (160)] were obtained in the absence of phthalimide. ... 

Details of the synthesis and reactions of glycofuranosylethynes, prepared via the reaction of 2,3 5,6-di-0-isopropylidene-a-D-mannofuranose with ethynyl magnesium bromide, have been published (see Vol. 8, p. 27). It is noteworthy that the glycofuranosylethynes do not obey Hudson s rules of isorotation. 

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).]...

Acetyl-2,3 5,6-di-0-isopropylidene-p-D-mannofuranose, 1-71 3-0-Acetyl-l,2 5,6-di-0-isopropylidene-p-D-talofuranose, 1-75 3-5-Acetyl-l,2 5,6-di-0-isopropylidene-3-thio-a-D-allofuranose, T-53... 

An analogous sequence of reactions with methyl 2,3-dideoxy-(lS)-pentopyranosid-4-ulose 4-(toluene-p-sulphonylhydrazone) (434) afforded l,5-di-0-acetyl-2,3,4-trideoxy-4-C-(phenylphosphinyl)-DL-gfiycero-pentofuranose (435). The Abramov reaction of 2,3 5,6-di-O-isopropylidene-a-D-mannofuranose with dimethyl phosphite yielded the oxaphosphorinane (436) by intramolecular transesterification. ° ... 

Similarly, starting from 2,3 5,6-di-0-isopropylidene-D-mannofuranose 72, a one-pot procedure that implies the synthesis of glycosyl sulfones by Horner-Wadsworth-Emmons olefination with phosphonate 73, followed by subsequent Michael addition and Ramberg-Backlund reaction92 gives compound 74 in 78% yield93 (Scheme 24). 

The second example concerns the study of acetonation of o-mannose (see Scheme 8) and allows a clear distinction between the use of 2,2-dimethoxypropane and 2-methoxy-propene. Thus, whereas D-matmose gives 2,3 5,6-di-0-isopropylidene-D-mannofuranose 5 by reaction of the free sugar with acetone [5,6] as well as with 2,2-dimethoxypropane [96], the major compound (more than 85%) obtained with 2-methoxypropene is 4,6-0-isopropylidene-D-mannopyranose 6 [52]. Once again, a confirmation of the better stability of furanoid acetals in this series is given by the selective hydrolysis of the 2,3 4,6-di-O-isopropylidene-D-mannopyranose 7 (by-product of the preceding reaction or quantitatively obtained by action of 2-methoxypropene on acetal 6), witch gives the furanoid monoacetal 8. Actually, the pyranoid monoacetal 9 can be easily prepared as soon as the anomeric hydroxyl group is protected by acetylation [52]. 

It is worth to note that P-acetoxy-a-diazoesters were also readily accessible through the reaction of monosaccharides in their hemiacetal form. However, such a reaction required the use of an equimolecular amount of diethylzinc creating likely very reactive zinc diazointermediates which react smoothly with aldehydes [l 02]. Applying this procedure KO and its 3-epimer were prepared, starting from 2,3 5,6-di-0-isopropylidene-D-mannofuranose [101]. 

The addition of methyllithium or methylmagnesium chloride to 2,3 4,6-di-O-isopropylidene-D-mannopyranose yielded a single D-g/ycero-D-monno-heptitol, whereas the same reaction with 2,3 5,6-di-0-isopropylidene-D-mannofuranose produced two diastereomers. The diastereoselectivity in the former case was attributed to a large ring chelate between the 0-5, the aldehyde group and the metal cation. " ... 

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