Pyranoside enol esters from

Anomeric triphenylphosphonium salts have been used as well as phenylsul-fides,but in the latter case extra stabilization is necessary (see below). Anomeric nitrosugars, which have been extensively studied in C-glycosylation reactions by Vasella, will be covered in Sect. 2.2.1 and ester enolates derived from 3-deoxy-2-ketoulosonic acids (sialic acid and KDO derivatives), which bear a structural similarity to 2-deoxy pyranosides, will be covered in Sect. 4.4. Deprotonation of anomeric phenylsulfones has been discussed in Sect. 2.1.1 and additional transformations on closely related compounds are presented in Scheme 14 [20]. Alkylation of phenylsulfone 54 with epoxide 55 provides adduct 56 which eliminates benzenesulfinic acid at room temperature to give the C(l)-alkylated glycal 57 a similar elimination is also observed with adducts derived from... 

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