Valienamine structure

Total synthesis of (+)-validamycins A and B starting from a common synthetic intermediate was elaborated by the following sequence. Tetra-(9-benzyl-(-l-)-valienamine (370), derived from 211, and the di-O-benzyl derivative (371) of the epoxide were coupled in 2-propanol to produce the protected dicarba compound (374), the structure of which was confirmed by conversion into (-1-)-validoxylamine B nonaacetate. Concurrently, compound 372 was glycosylated and the product oxidized with a peroxy acid, to afford a mixture of products from which the desired epoxide (373) was obtained in 70% yield. Coupling of 370 with 373 in 2-propanol at 120° afforded two carba-trisaccharides, and the major product (47%) was depro-tected and characterized as the dodecaacetate of validamycin B. The pro-... 

The majority of naturally occurring aminocarbasugars bears the amino functionality located at the pseudoanomeric position however, replacement of one or more hydroxyl groups by amino functions on the carbasugar backbone may offer great opportunities for structural and stereochemical variation. This section is subdivided into three subsections, dealing with the synthesis of validamine, valiolamine, and valienamine-type carbaglycosyl amine structures. 

Ogawa and co-workers have continued to develop syntheses of a large number of racemic branched-chain cyclltols, many related to natural products, from a common original starting material - the Diels-Alder adduct of acrylic acid and furan (see Vol.ll, p.l50 and Vol.13, p.l54). The structure of hydroxyvalidamine, a component of validamycin B, has been confirmed by the synthesis of Its racemic hexaacetate the racemic derivative (43) could be synthesized more efficiently, using the dibromide (44) and the cyclohexene (45) (Scheme 8). Syntheses of racemic valienamine CHgBr CH2OBZ 0—I OAc... 

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