Hexopyranoses oxidation

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). 

Hexopyranose disaccharides having a (1 —> 6)-linkage rapidly yield about five moles of formic acid per mole (see Fig. 6), that is, one from the nonreducing end and four from the reducing end-unit, and consume about six moles of oxidant per mole, the data corresponding to conversion of LVIII to LX. In the 1,4-hexopyranoses (for example, LIX), formic acid appeared... 

A distant, sulfur analog of l,6-anhydro-2,3,4-trideoxy-j3-D-glt/cero-hexopyranose (26) is (lR,5R)-6,8-dioxa-3-thiabicyclo[3.2.1]octane (241), which was prepared by periodic acid oxidation of levoglucosan (6), followed by reduction of the resulting dialdehyde 100 to diol 242, and by p-toluenesulfonylation to 243, and replacement of the two sulfonic ester groups of 243 with sodium hydrogensulfide.731... 

Dimethyl-1-a-D-ribofuranosylbenzimidazole 5-Acetyl-l-(3,5-0-isopropylidene-) -D-xylofuranosyl)uracil 2,3 -Didehydro-[5-methyl-2//-l,2,6-thiadiazin-3yl 4,6-di-O-acetyl-2,3-dideoxy-a-L-eryt/iro-hexopyranoside] 1,1 -di-S-oxide 3,1 -anhydro-[2-(4,6-di-0-acetyl-2,3-dideoxy-a-L-eryt/iro-hexopyranose-3-yl)-3-hydroxy-5-methyl-2if-l,2,6-thiadiazine] 1,1-dioxide ... 

The central scans in Fig. 7 are the normal, 100-MHz, n.m.r. signals of the H-1 and H-2 resonances of a fully mutarotated solution of 2-deoxy-D-arabtno-hexopyranose (7) in deuterium oxide. The assignment... 

TABLE 6.3 Periodate oxidation of linked hexopyranose residues... 

Syntheses of 3,4-Unsaturated Cyclic Compounds - Compound 30, available in three steps from 5-hydroxymethyl-l,6-anhydro-a-L-a//ro-hexopyranose was converted into ewMevoglucosenone by reaction with copper-quinoline (decarboxylation at C-5), zirconium oxide induced olefination at C-3 (reductive decarboxylation) then deacylation and oxidation. The 5-hydroxymethyl analogue of ent-levogluco-senone was also made from the same starting materials. ... 

Figure 5 lists the aldehydes which were made in quantities ranging from 10 g to 10 kg. Figure 6 shown a representative NMR spectrum of the aldehyde taken from the unpurified residue after lypophilization of the reaction mixture. This spectrum illustrates the specificity of the enzyme. Initially, we were concerned about the possible formation of uronic acids reported by some authors (25-27). However, we have no evidence for the presence of these by-products from the carbon-13 spectra of the oxidation products. On the other hand, the small signals between 90 ppm and 103 ppm may belong to dimeric products described by Maradufu and Perlin (28), All the aldehydes are hydrated as indicated by the presence of a peak at 88.7 ppm and the absence of peaks below 200 ppm. These aldehydes are relatively stable in the presence of base as evidenced by preparation of 5-C-hydroxymethyl-L-arabino-hexopyranoses (Equation 1). Even though the synthesis was carried out in 1 N NaOH, very little by-products resulted from elimination or retroaldol reactions at the pyranose ring. 

Other reactions such as acetolysis of 1,6-anhydro-P-hexopyranoses and per-acety-lation of hexoses with acetic anhydride [95], condensation of indole and various aldehydes [96], Baeyer-Villiger oxidation with H2O2 [97, 98], Perrier rearrangement [71], and generation and reactions of a-organylselanyl carbenium ions with nucleophiles [99] also proceeded well over scandium catalysts. 

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