Aza sugar synthesis

DHAP-Dependent Aldolases in the Core of Aza Sugar Synthesis... 

A simple synthesis of a 7-membered aza sugar from the unsaturated aldehyde 4 was proposed by Moutel.8 The same aldehyde 4 was used in the synthesis of modified aza sugars such as 5 (Fig. 2) 9 An interesting approach to polyhydroxylated 7-membered branched aza sugars (e.g. 8) was proposed by Estevez.10 Nitro sugar 6 underwent the... 

Synthesis of bicyclic aza sugars from D-xylose was reported. A key step involved reaction of the nitrone 9 with ethyl acrylate providing intermediate 10, which was finally converted into aza sugars (Fig. 4).11... 

Fig. 9 Application of RCM in the synthesis of eight-membered ring aza sugars.

Fig. 12 Synthesis of a simple aza sugar based on mercuration of its unsaturated precursor.

Application of simple sugars as starting materials for the preparation of optically pure complex products represents nowadays the classic methodology of organic synthesis it is covered by many comprehensive reviews, cited here only in references.88 These references provide the precise state-of-art in the synthesis of aza sugars, carbasugars and other derivatives. 

Another stereoselective synthesis (Scheme 11) is based on sugar aldehyde 35 and intermediate 36 subsequent 1,2-O-isopropylidine deprotection, N,0-debenzylation/olefin reduction/reductive cyclization in a single pot, and O-acetylation result in the formation of bicyclic aza sugar 37 (09TA1217). 

In this respect it is interesting to note that the tandem aldolization technique proved amenable also to the synthesis of a first C-glycosidic aza sugar (Scheme 2.2.5.19) [29, 36]. A rather simple dihydroxylated azido dialdehyde was generated from racemic azidocyclohexene 60 and subjected to FruA catalysis. The latter effected a smooth tandem addition to provide a diastereoisomerically pure bispyranoid azido C-disaccharide 61, from which the pyrrolidine-type aza sugar 62 was... 

The synthesis of the aza sugar D-nojirimycin (71 Scheme 20) [56], a well-known... 

The glycosyl a-amino aldehyde 70 obtained from the dialdose 49 through the nitrone 69 appeared nicely tailored for a rapid conversion to 71. This simply involved the reduction of the formyl group and removal of the hydroxyl and amino protective groups. This approach should be extendible to the synthesis of various aza sugars containing suitable structural modifications. 

G. C. Look, C. H. Fotsch, and C.-H. Wong, Enzyme-catalyzed organic synthesis Practical routes to aza sugars and their analogs for use as glycoprocessing inhibitors, Acc. Chem. Res. 26 182(1993). 

Aminomercuration aminoalditols The synthesis of the natural aza-alditol 1-deoxynojirimycin (4) from methyl a-D-glucopyranoside involves the reductive ring-opening (Zn) and reductive amination (NaBH3CN) of 1 to give 2 in 91% yield. Aminomercuration of 2 results mainly in the bromomercurial 3, which was converted into the aza-sugar 4 by reductive oxygenation and deprotection. 

Professor Nikolaos G. Argyropoulos was born in 1943. He received his B.Sc. in chemistry at Aristotle University of Thessaloniki (1968) and his Ph.D. at the same university, under the supervision of Professor N. E. Alexandrou. He worked as a postdoctoral research associate in the laboratory of R. Breslow at Columbia University (1980-81), and after that he returned to the Aristotle University of Thessaloniki where he become assistant professor (1985) and associate professor (1991). Since then, he is a permanent faculty member of the Aristotle University of Thessaloniki. His research interests are focused on heterocyclic synthesis and the synthesis of carbohydrate mimics, especially aza sugar derivatives as possible bioactive compounds. He was author of the chapter l,4-(Oxa/thia)-2-azoles in CHEC-II(1996). He is also the author of four relevant chapters that appeared in Science of Synthesis (vol. 13) dealing with all possible heteroaromatic (oxa/thia)-azoles. 

Enzymatic synthesis of aza sugars as inhibitors of carbohydrate metabolism 93ACR182. 

Since numerous applications of nitroso dienophiles in natural product synthesis [8] and, in particular, aza sugars [332] have been reviewed in the last years, these topics will only be discussed briefly here and only some exemplary and very recent transformations are presented in this article. 

In a different study, 2-D-deoxyribose-5-phosphate aldolase (DRA) was used in the synthetic direction to synthesize with high stereospecificity a wide range of aldol products169 according to equation 29 for a variety of X and Y substituents. The method proved to be an efficient one for the synthesis of some aza-sugars. 

N-Acetylneuraminic acid aldolase (NeuAc aldolase) is commercially available and has been the subject of much attention [49]. NeuAc aldolase catalyzes the aldol reaction between pyruvate and mannose or mannose derivatives. The enzyme activates the donor as its enamine, similar to the Type I aldolase described above (Scheme 5.21). The enzyme has been used for the synthesis of aza sugars and var-... 

Dimethyl-l,3-dioxan-5-one SAMP/RAMP hydra-zones j were used as dihydroxyacetonephosphate equivalents in the synthesis of C2 symmetric ketones (eq 5), aza sugars with novel substitution patterns, or C5 to C9 deoxy sugars. SAMP hydrazones of 2-oxo esters represent novel phosphoenolpyruvate (PEP) equivalents. a,a-Disubstituted spiroacetals are accessible via the alkylation of ketone SAMP/RAMP hydrazones. ... 

Unlike the amine analogs a-silylamido ( )-vinylsilanes undergo cyclization to produce tetra hydropyridines with retention of absolute and relative stereochemistry. This method has been utilized for the synthesis of the aza-sugars, (—)-l-deoxymannojirimycin and (-l-)-l-deoxyallonojirimycin. 

Hudlicky, T, Rouden, J, Luna, H, Allen, S, Microbial oxidation of aromatics in enantiocontrolled synthesis. 2. Rational design of aza sugars (emio-nitrogenous). Total synthesis of (-l-)-kifunensine, mannojirimycin, and other glycosidase inhibitors, J. Am. Chem. Soc., 116, 5099-5107, 1994. 

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