2-deoxyglycosides synthesis

Other methods have gained practically no importance. Special problems in the application of methods (a)-(d) to 2-deoxyglycoside synthesis will be reported in Section 1.2.7. 

The Direct Synthesis of Deoxyglycosides Employing Crystalline O-Acyldeoxyglycosyl Halides... 

Of the many methods described for glycoside synthesis, those predominantly used in current oligosaccharide synthesis, in which the glycosyl donor has O- or N- functionality at C-2 (that is, excluding 2-deoxyglycosides), are the following ... 

Glycals have been widely used as glycosyl donors, especially for the synthesis of 2-deoxyglycosides 45b 47 In addition, they can be readily converted into 2,3-unsaturated... 

Y. Ito and T. Ogawa, Sulfenate esters as glycosyl acceptors A novel approach to the synthesis of 2-deoxyglycosides, Tetrahedron Lett. 28 2123 (1987). 

The reaction produces a stereoselective synthesis of a- or (S-2-deoxyglycosides. a-Linked disaccharides such as 1 can be prepared by a three-step sequence with high stereocontrol. 

A. Kirschning, M. Jesberger, and A. Schonberger, The first polymer-assisted solution-phase synthesis of deoxyglycosides, Org. Lett., 3 (2001) 3623-3626. 

M. Perez and J.-M. Beau, Selenium-mediated glycosidations A selective synthesis of P-2-deoxyglycosides, Tetrahedron Lett., 30 (1989) 75-78. 

Additions to glycals can also give products from which glycosylating agents can be made for the specific synthesis of 2-amino-2-deoxyglycosides, and this approach adds to the methods available for making such glycosides... 

A reliable approach for the synthesis of 2-deoxyglycosides is through haloalkoxyl-ation of glycals followed by the subsequent reductive removal of the halide at C2. 

SCHEME 3.25 Synthesis of a 2-deoxyglycoside using the glycal approach. AIBN, azobisisobutyronitrile. 

SCHEME 3.26 Approaches utilized for the synthesis of 2-amino-2-deoxyglycosides from glycals. 

SCHEME 4.5 1,2-Migration in the stereoselective synthesis of 1, 2-tram (amino)-glyco-sides and 2-deoxyglycosides as reported by (a) Danishefsky, (b) Yu, and (c) Lowary. Ac, acetyl All, allyl Bn, benzyl Bz, benzoyl DTBMP, 2,6-di-fert-butyl-4-mcthyl pyridine TBDPS, ferf-butyldiphenylsilyl THF, tetrahydrofuran TIPS, triisopropylsilyl Tol, 4-tolyl. 

Nicolaou [46] has also exploited a seleniiun Unker cleaved using radical conditions in the solid-phase synthesis of 2-deoxyglycosides, 2-deoxy-orthoesters and 2,3-allyl orthoesters. Resin-bound tributyltin selenolate 251 was conveniently synthesized in two steps from a selenenyl bromide resin. Treatment of 251 with a trichloroacetimidate donor gave resin-bound se-... 

Scheme 64 Selenium linker cleavage in the synthesis of 2-deoxyglycosides by Nicolaou [46]...

It is the intention of this section to present recent advances in the the art of modern oligosaccharide synthesis, with particular emphasis on methods for the stereoselective assembly of 2-deoxyglycosides. The strengths of the various chemical methodologies will be discussed in a selected number of examples. 

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