Cyclitol, amino-, antibiotics, synthesis

During the past nine years the subject of total synthesis of sugars and cyclitols has been vividly developed. The discovery of a large number of unusual sugars in nature—deoxy, amino, branched chain sugars (many of them components of antibiotics)—made their synthesis attractive. On the other hand, improvements in organic reagents and synthetic methods allowed a return to older preparations which could be now better performed. Finally, some synthetic ideas already described in this series, in the first chapter of the volume on the total synthesis of carbohydrates, are further expanded. 

The known 7-e carboxylic acid 506, obtained by the condensation of acrylic acid with furan, was used as a substrate for synthesis of validamine, (510) a component of validamycin antibiotics. The treatment of 506 with hydrogen peroxide in formic acid gave the tricyclic compound 507, which after reduction and hydrolysis afforded cyclitol. Treatment of 508 with 2,2-dimethoxy-propane in the presence of an acid gave a mixture of diisopropylidene derivatives in which compound 509 was predominant. Introduction of an amino group, by way of a tosyl ester and azide displacement, followed by hydrogenation and hydrolysis, completed the synthesis of DL-val-... 

Istamycin A (4) and istamycin B (5) have been isolated from the culture broth of Streptomyces tenjimariensis, and sannamycin A (identical with istamycin A) and sannamycin B (6) from the culture broth of Streptomyces sannan-ensis- these are likewise 1,4-diamino-cyclitol ot-glycosides of 6-A -methyl-purpurosamine C. (The synthesis of this amino-sugar is mentioned in Chapter 8.) Derivatives of the amino-sugar and cyclitol constituents of fortimicin B have been prepared by benzyloxycarbonylation and alcoholysis of the antibiotic. ... 

Reviews have appeared on the synthesis of aminoglycoside antibiotics, and on the formation of new aminocyclitol antibiotics by mutants of amino-cyclitol-producing organisms fed with aminocyclohexanol or related subunits. The structures of eight minor components of the nebramycin complex elaborated by Streptomyces tenebrarius have been elucidated besides neamine and related pseudo-disaccharides, the new components are pseudo-trisaccharides related to kanamycin B, and the 3 -hydroxy analogue of the principal component of the complex, apramycin (see Vol. 10, p. 130). ... 

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