Sugars 3-amino-2,3-dideoxy, synthesis

An essentially similar synthesis of 2-amino-2,6-dideoxy-L-talose has been reported by Collins and Overend, involving reduction of the oxime (6) with lithium aluminum hydride. Subsequent acidic hydrolysis of the product yielded a mixture of epimeric glycosides of amino sugars, from which a methyl glycoside of an amino sugar hydrochloride (9), m.p. 265° (dec.), [a]D —8.4° (c, 1.55, in water), was obtained by fractional recrystallization. Acetylation and acidic hydrolysis of this glycoside yielded 2-amino-... 

Taguchi, T. Kitagawa, O. Suda, Y. Ohkawa, S. Hashimoto, A. litaka, Y Kobayashi, Y. Synthesis of 3,3-difluoro-2-azetidinones and 2,3-dideoxy-2,2-difluoro-3-amino-sugars through the reformatsky reaction of difluoroacetate with imine. Tetrahedron Lett. 1988, 29, 5291-5294. 

The presented review describes total syntheses directed towards 6-amino-6,8-dideoxy-D-eryt/iro-D-galacto-octose, commonly named lincosamine - the sugar component of the antibiotic lincomycin. In the first part we present total syntheses of lincosamine that start from carbohydrate precursors. The D-galactose-derived aldehyde is the most frequently used synthon. In the second part, total syntheses of lincosamine from non-carbohydrate precursors are presented. This part of the review is divided into two subsections. The first one groups syntheses based on the application of furan compounds. In the second one we present a hetero-Diels-Alder approach to the synthesis of lincosamine. 

A second aid to the chemical classification of polyenes is the presence in the antibiotic of either a hexosamine sugar or an aromatic moiety. The presence of sugars is a characteristic of macrolide antibiotics. Polyene hexosamines are similar to the sugars present in the non-polyene macrolides [27]. The structure of polyene hexosamines has been determined and with one exception, the carbohydrate is mycosamine [28—30], the structure of which has been unequivocally established by chemical synthesis [31] as 3-amino-3,6-dideoxy-D-mannopyranose (1). The sugar perosamine, 4-amino4,6-dideoxy-D-mannose (2), an isomer of mycosamine, has been isolated from perimycin [31,32]. 

The synthesis of 2-acetamido-1,6-anhydro-2,3-dideoxy-B-D-rlbo-hexopyranose from a 3-thlo-sugar by reductive desulphurization is covered in Chapter 9. Reduction (NaBH ) of secondary mesylates with a vicinally related trans-dlallylamlno group proceeds to give deoxygenated products via aziridinium ion intermediates, sequence, sometimes the product is that of amino migration examples are detailed in Chapter 9. 

Intramolecular glycosylation using a thioglycoside as donra (see VoL 27, p. 245) has been applied ro the synthesis of AZT.73 Base-sugar condensation was used to prepare some AZT analogues of type 69.10 The 3-amino-2, 3 -dideoxy-p-D-ribofuranosides of adoiine and guanine... 

Azide displacements on sugar sulphonates and halides continue to be used extensively in the synthesis of amino-sugars. Such displacements have been used in the synthesis of derivatives of the methyl 3-amino-2,3-dideoxy-a-L-hexopyranosides... 

TLC on silica gel G has been useful particularly in the organic synthesis of amino sugars for the characterization of derivatives which are not readily detected on paper. It has found application in the synthesis of 4-acetamido-4-deoxy-D- reofuranose [41], 2,6-diamino-2, 6-dideoxy-D-mannose dihydrochloride [42], 2,3-epimino-hexopyranosides [43], 2-amino-2,6-dideoxy-D-galactose [44], the l-O-acyl-2-acylamido-... 

A full paper on the synthesis of prumycin [4-(D-alanylamino)-2-amino-2,4-dideoxy-L-arabinose] from D-xylose has appeared (see Vol. 10, p. 137) an intermediate in that synthesis, benzyl 2,3-anhydro-4-azido-4-deoxy-)S-L-ribopyranoside, was also used to prepare the isomeric diamino sugar, 4-(d-alanylamino)-3-amino-3,4-dideoxy-L-xylose. A closely related synthesis of the D-xylose isomer (21) of prumycin, from the same laboratory, is outlined in Scheme 10. A further report on the synthesis of prumycin from benzyl... 

---