Aminosugars synthesis

J. Saha and M. W. Peczuh, Expanding the scope of aminosugars synthesis of 2-amino septanosyl glycoconjugates using septanosyl fluoride donors, Chem. Eur. J., 17 (2011) 7357-7365. 

Dihydroisoxazole derivatives are recognized as protected y-amino-alcohols, which can be employed for preparation of aminosugars. Synthesis of protected L-daimosamine based on this motif, is presented in the Scheme 20 [83]. 

Cumpstey I, Agrawal S, Martm-Matute B et al (2011) Iridium-catalysed condensation of alcohols and amines as a method for aminosugar synthesis. Chem Commiin 47(27) 7827—7829... 

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). 

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

A common intermediate for all the nucleotides is 5-phosphoribosyl-l-diphosphate (PRPP), produced by successive ATP-dependent phosphorylations of ribose. This has an a-diphosphate leaving group that can be displaced in Sn2 reactions. Similar Sn2 reactions have been seen in glycoside synthesis (see Section 12.4) and biosynthesis (see Box 12.4), and for the synthesis of aminosugars (see Section 12.9). For pyrimidine nucleotide biosynthesis, the nucleophile is the 1-nitrogen of uracil-6-carboxylic acid, usually called orotic acid. The product is the nucleotide orotidylic acid, which is subsequently decarboxylated to the now recognizable uridylic acid (UMP). 

The (2S,3R) methyldiols (4), generated in a multlenzymatlc process in fermenting baker s yeast from a-position unsaturated aromatic aldehydes, are used as starting materials in the synthesis of deoxy- and deoxy aminosugars of the L-series, including the L-daunosamine and L--vancosamine derivatives 17 and 34. 

Application of this methodology to the synthesis of a variety of aminosugar derivatives involving Z-vancosamine (72) has been performed. 

E. Kozlowska-Gramsz and G. Descotes, Addition of nitrenes to cyclic vinyl ethers. Application to the synthesis of aminosugars, Tetrahedron Lett., 22 (1981) 563-566. 

This selective deprotection has been exploited in order to obtain C-glycosides of aminosugars, the synthesis of which is complicate when starting from the corresponding aminosugar. (11)... 

Novel Synthesis of Natural Pseudo-aminosugars, (+)-Valienamine and (+)-Validamine... 

In combination with the range of standard transformations of alcohols, alkenes, and vinylsulfides, these silicon-tethered additions of functionalized radicals offer a versatile and stereoselective approach to amino alcohol synthesis. Whereas vinyl and 2-oxoethyl radicals have not yet been demonstrated as competent participants in the various intermolecular additions reported in the literature, the temporary tether approach allows such functionalized fragments to be installed in an efficient and stereoselective manner. Synthesis of the aminosugar daunosamine from achiral precursors shows how this concept, employing hydrazone radical acceptors, can be merged with asymmetric catalysis to achieve practical synthetic advances. 

A-Boc protected oxazolidines found application in the enantioselective synthesis of aminosugars <030L3001>. Oxazolidin-2-ones were also used as tethers for the stereoselective [4+3] cycloadditions of nitrogen-stabilised oxyallyl cations via epoxidation of allenamides <03JA12694>. 

A significant advance13 towards the synthesis of aminosugars uses halocyclocarbamation in cyclic systems which proceeds under high regio- and stereocontrol. 

Synthesis of another type of acyclo nucleosides start with thiophene-3-isocyanate and aminosugars to afford, with KOH/dioxan, thieno[3,2-pyrimidine nucleosides, while acryloylisocyanates react readily with aminoglucose or open chain analogues, resulting in open-chain (acyclo)ur-acil and an acyclo-acyclo species [92S(ip)J (Scheme 16, Scheme 17). 

Roush, R W, Hunt, J A, Asymmetric allylboration of 2-iV,3-0-isopropylidene-A-Boc-L-serinal diastereoselective synthesis of the calicheamicin 7 aminosugar, J. Org. Chem., 60, 798-806, 1995. 

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