Sugars oxidative cleavage

The favored oxidative cleavage of a primary-secondary over a primary-tertiary vicinal diol grouping has been utilized in the synthesis of branched-chain sugar derivatives.482,483... 

Reaction of nitromethane and monosaccharide-derived dialdehydes is a useful tool that has been broadly used for the preparation of nitro and amino sugars, and carbocycles.30 Dialdehydes can easily be obtained by oxidative cleavage of conveniently protected monosaccharides with sodium periodate. Their subsequent Henry reaction with a nitroalkene, commonly nitromethane, usually gives isomeric mixtures that require the isolation of the major isomer.31 Thus, treatment of the D-ribose derivative 27 with sodium periodate gave dialdehyde 28, which was subjected to a Henry reaction with nitromethane, to afford nitrosugar 29 as an epimeric mixture (Scheme 11).32... 

Nitrocyclohexadiene 93a reacted with 4.0 equivalents of cyclopentadiene in toluene at 110°C for 96 h, producing the 10-glyco-l-nitrotricyclo[5.2.2.02,6]undeca-3,8-diene 96a in 70% yield. Subsequent treatment with potassium carbonate in a methanol-water (9 1) solution followed by oxidative cleavage of the sugar side chain with sodium metaperiodate afforded aldehyde 96c. Reduction of the aldehyde with sodium borohydride produced alcohol 96d. 

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). 

The kinetics and mechanisms of the oxidation of DNA, nucleic acid sugars, and nucleotides by [Ru(0)(tpy)(bpy)] and its derivatives have been reported. " The Ru =0 species is an efficient DNA cleavage agent it cleaves DNA by sugar oxidation at the 1 position, which is indicated by the termini formed with and without piperidine treatment and by the production of free bases and 5-methylene-2(5//)-furanone. Kinetic studies show that the I -C— activation is rate determining and a hydride transfer mechanism is proposed. The Ru =0 species also oxidizes guanine bases via an 0x0 transfer mechanism to produce piperidine-labile cleavages. 

The Grignard reagent from (l-chloroethyl)dimethylphenylsilane, prepared in turn by a-methylation of (chloromethyl)dimethylphenylsilane, acts as a hydroxyethylating reagent after oxidative cleavage its use can be seen in a stereoselective synthesis124 of lincos-amine, the sugar component of the antibiotic lincomycin. 

Starting with (+)-26, L-noviose, the sugar moiety of antibiotic novobiocin, was obtained. Thus, (+)-26 was converted into 56, via 41, which on reaction with methyllithium followed by oxidative cleavage and deprotection gave L-noviose (Scheme 16).21... 

Stereoselective rearrangement reactions can involve sugar-linked functionalities. An example of this type is the Overman rearrangement of allylic trichloracetimidates formed from a D-glucofuranose derivative 20 [36]. This methods affords (L)-a-ami-no acids 25 from (Z)-allylic imidate 23 and (R)-a-amino acids 25 from ( )-imidates 23 with a diastereoselectivity of about 16 1. The oxidative cleavage of compound 24 with Ru04 yields the a-amino acid 25, (Scheme 15). 

The oxidant can be formulated either as a hydroxy radical bound to Cu(II) or as a hydroxide ligand on Cu(III). In either case, the activated complex is capable of strand scission, and the cleavage pattern suggests that the oxidant is nondiffusible and therefore bound to the metal (17). Cleavage by this reagent involves sugar oxidation, as discussed in subsequent paragraphs. 

The ability to incorporate deuterium or tritium selectively into appropriate positions on nucleotides has had a tremendous impact on mechanistic studies on sugar oxidation. In particular, Stubbe and coworkers have shown that when thymidine deuterated at the 4 position is incorporated into restriction fragments, sequence-selective isotope effects are observed for cleavage by Fe-BLM (12). These isotope effects are essentially equal for the radical and carbocation pathways (Scheme... 

Aldol-type cyclization of dialdehydes with nitroalkanes is a valuable synthetic route to amino sugars, amino cyclitols and nucleosides of amino sugars. Recently, the cyclization of the di- and tetra-alde-hydes d ved from sucrose (15) with nitroalkanes has appeared. It is noteworthy that the oxidative cleavage of sucrose with LTA affords the dialdehyde selectively (Scheme 8). ... 

A few 4a-carba-furanoses were synthesized using the same methodology. However, after saturation of the alcohol 40 the syntheses diverged when protection of the hydroxyl, cleavage of the acetonide and oxidative cleavage of the diol afforded the aldehyde 44 (Scheme 8.15). This compound underwent an aldolisation reaction whose stereoselectivity could be controlled by the reaction temperature. Specifically, at — 90°C the bicyclic product 46 was obtained in a yield of 71%. Alternately, bicyclic derivative 45 was the principle product obtained when the reaction was run at room temperature (78%). Reduction of the lactone and desilylation afforded 4a-carba-(3-D-xylofuranose from isomer 45, whereas 4a-carba-(3-D-ribofuranose was formed from 46. Isomerisation of compound 40 led to the synthesis of two other isomeric carba-sugars 4a-carba-(3-L-lyxofuranose and 4a-carba-(3-L-arabinofuranose [36]. 

The only C3 sugar is the rather unstable glyceraldehyde best used in a protected form such as 107 or 109 available from the oxidative cleavage of mannitol derivatives such as 106. 

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