Glycosylamines oxidation

Ellis and Honeyman80 have raised strong doubts as to the validity of the structural determinations that have been applied to glycosylamines these doubts are based on the fact that such compounds are readily isomerized, as evidenced by their mutarotation. The formation of a trityl ether cannot be considered valid evidence for the presence of a primary hydroxyl group in the compound tritylated, and periodate oxidation, which is often excessive, may lead to faulty conclusions. 

Although much work has been done in an attempt to elucidate the structure of iV-substituted glycosylamines, rigid proof of their structures has not yet been achieved.43 Spectroscopic evidence is inconclusive,69 whilst chemical methods are of limited value because equilibrium between open-chain, pyranose, and furanose forms is possible. However, all such derivatives as ethers and esters so far prepared directly from A-glycosylamines have been shown to be pyranoid, and periodate oxidation of some N-glycosylamines has confirmed this conclusion.70 71... 

Tri- and tetra-peptide analogues incorporating an a-atnino acid at the anomeric position, e.g. 33, were synthesized by way of a novel oxidative ting contraction of 2-amino-2-deoxy-heptonic acid derivative 31 to give heptulosonic acid glycosylamine 32 and its anomer (Scheme 6). The spirocyclic diketopiperazine 35 was obtained from 34 it could be 0-deprotected under acidic conditions then anomerized to the thermodynamically favoured C-2 q>imer with strong base. See also reference 3 for a general route to anomeric a-amino acids. 

Differences were observed in the e.s.r. spectra of the epimeric methyl 2,3,6-tri-Q-benzoyl-4-deoxy-4-hydrojq lamino-o-D-gluco- and -galacto-pyranosides. A one step synthesis of water-soluble spin-labelled glycosylamine derivatives involved condensation of amino-substituted N-oxides with free sugars (see Chapter 10) e. r. spectra were recorded. ... 

Synthesis of the morpholine-derivative renin inhibitor BW-175 (254) and the spiroammonium derivative 255 are described in chapter 18. The antibiotic ( —)-anisomycin 258 has been prepared from glycosylamine 256. Grignard addition, oxidation and cyclization affords pyrrolidinone 257 which was elaborated by known means to 258. ... 

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