Thiophenyl-glycosides

Thiophenyl Glycosides and Selenophenyl Glycosides (Different Donors, Common Activator) Changing from thioethyl glycosides to selenophenyl glycosides... 

C-Glycosides. Thiophenyl glycosides undergo ready free-radical allylation with allyl- or methallyltri- -butyltin. Thus the L-lyxose derivative 1 reacts with allyltri-/ -butyltin under photochemical initiation to give 2 and 3 in the ratio 90 10. The reaction... 

Zhang, Z, Magnusson, G, Conversion of p-methoxyphenyl glycosides into the corresponding glycosyl chlorides and bromides, and into thiophenyl glycosides, Carbohydr. Res., 295, 41-55, 1996. 

Conversion of CB glycosides to glycosyl fluorides and thiophenyl glycosides... 

An additional example illustrating the utility of thiophenyl glycosides in free radical mediated C-glycosidations was reported by Waglund, et a/.6 As shown in Scheme 5.2.4, 1-methylcarboxy-l-phenylthioglycosides were treated with allyltributyltin and irradiated with ultraviolet light. The resulting C-allyl derivatives were formed in approximately 30% yields with the stereochemical... 

Notes and discussion. In this method, stable thiophenyl glycoside donors are employed, and NIS is used to effect both tethering and glycosylation of the substrate. Moreover, by using dichloroethane as solvent, it is possible to perform both of these reactions in one-pot. 

The D-allal derivative 1 was formed by treating the unsaturated 1-thiophenyl glycoside 2 first with MCPBA then with diethylamine to effect a [2,3] sigmatropic rearrangement of the intermediate sulfoxide. Product 1 was incorporated into the core trisaccharide unit of esparamicin and the aryl tetrasaccharide unit of calicheamicin. ... 

Reactions with secondary acceptors proceeded in lower yields and exhibited sharply diminished stereoselectivities. It should be mentioned that 1,2-epoxides can be converted [43] to other glycosylating agents, thiophenyl glycoside 66, pentenyl glycoside 67, fluoride 68, which can be helpful after acylation at C-2 for the synthesis of 2-deoxy-P-glycosides (Scheme 15). 

To assess the orthogonality of the above-mentioned combination of reactions, the interconversion of the two anomeric potential leaving groups phenylthio and fluoro group was performed. Thiophenyl glycoside 1 was treated under Nicolaou s conditions [20] a) to yield the glycosyl fluoride 2 quantitatively. The fluoride 2 could. 

This triol is next glycosylated with the previously reported thiophenyl glycoside 90, as shown in Scheme 28. This critical step of the synthesis demonstrates that the... 

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