A Rapid Permethylation of Glycolipid, and Polysaccharide Catalyzed by Methylsulfinyl Carbanion in Dimethyl Sulfoxide.

An effective, and rapid permethylation of complex carbohydrates noted in the head ing is to be reported in this letter. Methy lation of a complex carbohydrate is a difficult and painstaking task, but if successful, it offers good confir_nation of the chemical structure (e.g. 1-3).. With more recognition of the significance of complex carbohydrates, roles played in determination of specificities of hormones, immunity, biological transport, and in various pathological phenomena, it has become more urgent to learn the chemical structure. For this purpose, permethylation on a micro scale applicable to the complex carbohydrates is desired. The alcoxide for mation, greatly catalyzed by methylsulfinyl carbanion (I) in dimethyl sulfoxide, followed by methylation with methyl iodide was found to be applicable, in some degree, for this purpose. Since Whistler and BeMiller des cribed an extraction of glycogen from tissue by dimethyl sulfoxide (4), 'non-aqueous' chemical reactions might be carried out in this extremely polar, but stable solvent. Not only glycogen but also 'Fr. 4-urinary glyco protein' (5, 6), ovomucoid, a certain sub fraction of the Wilson gastric mucin, and various glycolipids were found to the more or less soluble in this solvent. Therefore, it was undertaken to demonstrate the presence of various kinds of acyl residue in this solvent by ` hydroxylaminolysis' of the urinary glyco protein * While studying along this line, the author learned that Corey and his group developed a new reaction, using methyl sulfinyl carbanion, the conjugate base of dimethyl sulfoxide (7). The Witting type synthesis was achieved with great ease (8, 9) by a strong nucleophilic property of the carbanion on one hand, and on the other