1- aminosugars

Aminosugars are the result of replacement of one or more hydroxyl groups in a sugar by amino groups. They are formed in nature by transamination processes (see Section 15.6) on appropriate keto sugars, which are themselves the product of regiospecific 

D-Giucosamine and o-gaiactosamine, usually as A-acetyl derivatives, are part of the structures of several natural polysaccharides, whilst other uncommon aminosugars are components of the aminoglycoside antibiotics. We have also noted the occurrence of A-glycosides, where the nitrogen substitution is at the anomeric centre (see Box 12.3). 

A simple chemical approach to aminosugars is to use Sn2 displacement by ammonia of a suitable leaving group, such as a tosylate (toluene jc-sulfonate, see Section 7.13.1). This process can be made selective for position 6, since the less-hindered primary alcohol group is more readily esterified than the secondary alcohols. 

2-Aminosugars such as glucosamine may be synthesized by a modified Kiliani-Fischer process (see Box 12.1). The starting aldose, here o-arabinose, is treated with ammonia, producing an imine, and then with HCN to yield epimeric 2-aminonitriles. The 

Protecting groups such as cyclic acetals and ketals may also be employed to achieve selective reactions (see Section 12.5). 

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The few macrolides having 12-membered rings are Hsted in Table 2. Methymycin (12, R = OH, R = H), isolated from culture broths of a Streptomjces species (29), was the first macroHde stmcture elucidated (30). It is comprised of the aglycone methynolide (13, R = OH, R = H) and the aminosugar desosamine (1, R = OH, R = H) (31,32). Methymycin was also the first conventional macroHde made by total synthesis (33). 

The anthracyclines represent a broad family of antibiotics that exhibit activity in numerous tumors. The first anthracyclines, doxorubicin (DOX) and dau-notubicin (DNR), were isolated from Streptomyces var peucetius they were shown to be composed of a tetracyclic ring system with adjacent quinone-hydro-quinone moieties, a short side chain with a carbonyl group, and an aminosugar bound to the C-7 of the four-ring system. DOX and DNR only differed in the side chain terminus (-CH2OH in DOX vs. -CH3 in DNR). Second generation anthracyclines, like epitubicin (EPI) and idatubicin (IDA), were obtained after minor chemical modifications of DOX or DNR, respectively (Fig- 1). 

Roston, D. A. and Rhinebarger, R. R., Evaluation of HPLC with pulsed-am-perometric detection of an aminosugar drug substance, /. Liq. Chromatogr., 14, 539, 1991. 

Daniels Structure of the Aminosugar derived from Streptothricin and Streptolin B. J. Amer. chem. Soc. 78, 4817 (1956). 

Aminosugar acid Aminosugar HBTU Oligosaccharide mimic 89 2005AGE2096... 

Erythromycin is a macrolide antibiotic consisting of the aglycone, erythronolide A the aminosugar, desosamine and the neutral sugar, cladinose. 

Special topics (synthesis of P-mannosides, furanosides, sialosides, glycosides of aminosugars and deoxysugars, if applicable)... 

Intramolecular cyclizations of silyl nitronates were also used in the preparation of aminosugars. In 2003 Kudoh et al. reported the stereoselective conversion of 2-nitroalkanols by silyl nitronate generation followed by an intramolecular nitronate-olefin [3 + 2] cycloaddition reaction (Scheme 51).88... 

Aminosugars are the basic compounds of a new class of highly biodegradable detergents based on re-growing resources . Alkyl glucamides (AGs) (e.g. C12/i4-A -methyl glucamides) are one of the main... 

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