Hexopyranoses synthesis

Cerny M (1994) 1,6 2,3- and 1,6 3,4-Dianhy-dro-j6-D-hexopyranoses. Synthesis and preparative applications. In Witczak ZJ (ed) Frontiers in biomedicine and biotechnology. Levoglucosenone and levoglucosans, chemistry and applications. ATL Press, Mount Prospect, 2 121... 

Hexamine — see Hexamethylenetetramine 1,4,7,10,13,16-Hexaoxacyclooctadecane — see [18]Crown-6 Hexazinone as herbicide, 1, 187 Hex-2-enopyranoside, 2,3-dideoxy-synthesis, 1, 464 Hexobarbital, 3, 150 Hexogen, 3, 530 a-D-galacto- Hexopyranose nomenclature, 1, 31 Qf-D-ido-Hexopyranose nomenclature, 1, 31... 

J.-C. Florent and C. Monneret, Stereocontrolled route to 3-amino-2,3,6-trideoxy-hexopyranoses. K-10 Montmorillonite as a glycosidation reagent for acosaminide synthesis, J. Chem. Soc., Chem. Commun. (1987) 1171-1172. 

T. Komano worked with him. The work accomplished at that time included the following N-debenzyloxycarbonylation of 1,3,4,6-tetra-0-acetyl-2-(benzyloxycarbonyl)amino-2-deoxy-D-hexopyranoses in the conversion of a,/3-acetoxy to glycosyl bromide (1961) oxidative cleavages of 1,2-diamino sugars and their significance in the mechanism of the aminocarbonyl reactions (1962) and synthesis of 2-amino-2-deoxy-/3-o-glucosides via 3,4,6-tri-D-acetyl-2-benzylsulfonamido-2-deoxy-a-D-glu-copyranosyl bromide (1962). 

T.-M. Cheung, D. Horton, and W. Weckerle, Preparative synthesis of 3-amino-2,3,6-trideoxy-L-/yv<9-hexopyranose derivatives, Carbohydr. Res., 74 (1979) 93-103. 

With respect to five-membered lactones fused to hexopyranose units, some approaches have been reported so far and the exploitation of their synthetic potential has led to the access of new carbohydrate derivatives. Bicyclic derivatives of this type are key intermediates in the synthesis of the epimer at C-3 of the sugar moiety contained in miharamycins [212, 213]. The latter are antibiotics known to inhibit strongly Pyricularia oryzae, which produces the rice blast disease. These compounds are also considered to be a potential bioterrorism agent (Scheme 42). Hence, the 3,3-spiroepoxide 176 was converted into the 3-C-cyanomethyl derivative 177, the hydrolysis of which led to spontaneous cyclization in the presence of... 

Scheme 45 Synthesis of a hexopyranose-1,2-fused butyrolactone from a 2-C-malonyl glucoside...

Scheme 48 Synthesis of butenolides fused to pento- or hexopyranoses and thiosugar analogs from furanos-3-nloses...

A similar approach, involving condensation of 4-nitro-2-butanol with sodium glyoxylate309 in the presence of sodium hydrogencarbon-ate offers a route to 3-amino-3,4,6-trideoxy-DL-hexopyranoses. Two lactones, 552 and 553, were formed during the reaction (overall yield, 42%) in the ratio of 3 1 these lactones may be considered to be potential precursors of a variety of isomeric 3-amino sugars. The synthesis... 

Prom the viewpoint of a synthesis chemist, carbohydrates would appear to be severely overfunctionalized. Thus, in a hexopyranose, one has to contend with five hydroxyl groups distributed over six carbon atoms. Furthermore, four of the hydroxyl groups are chiral. Obviously, to cany out synthetic manipulations on such molecules one has to learn to protect hydroxyl groups (or amino groups in the case of aminodeoxy sugars) to leave free only those destined for reactions. Therefore, a rich repertoire of protecting gronp manipulations for this purpose has evolved [1,2]. Table 1 shows some of the more common ones in current use. 

Dideoxy-D-eryt/zro-hexopyranose (172) has been obtained from 3-deoxy-D-eryt/zro-pentose (171, Scheme 51)248 as an intermediate for the synthesis of the lactone moiety of inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, that lowers cholesterol levels. 

P.-T. Ho and S. Chung, Synthesis of 2,4-dideoxy-D-eryi/tro-hexopyranose. An intermediate for synthesis of the lactone moiety of inhibitors of hydroxymethylglutaryl-coenzyme A reductase, Carbohydr. Res., 125 (1984) 318-322. 

M. Sharma, R. J. Bernacki, M. J. Hillman, and W. Korytnyk, Fluorinated carbohydrates as potential plasma membrane modifiers. Synthesis of 3-deoxy-3-fluoro derivatives of 2-acetamido-2-deoxy-D-hexopyranoses, Carbohydr. Res., 240 (1993) 85-93. 

D. Lafont, P. Boullanger, O. Cadas, and G. Descotes, A mild procedure for preparation of 1,6-anhydro-jS-D-hexopyranoses and derivatives, Synthesis, (1989) 191-194. 

J. Karban, M. Budesinsky, M. Cerny, and T. Trnka, Synthesis and NMR spectra of l,6-anhydro-2,3-dideoxy-2,3-epimino- and l,6-anhydro-3,4-dideoxy-3,4-epimino-/i-D-hexopyranoses, Collect. Czech. Chem. Commun., 66 (2001) 799-819. 

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