Synthèses de la d-gluco-(2,3:5′,6′)-2′-( R)-méthyl-3′-morpholinone (amide interne de l'acide muramique)

Abstract

Alkaline hydrolysis of the N-acetyl group of benzyl 2-acetamido-4,6- O-benzylidene-3- O-( d-1-carboxyethyl)-2-deoxy-α- d-glucopyranoside with ethanolic potassium hydroxide gave the free crystalline amine, which was cyclized by heating or by treatment under very mild acidic conditions or with diazomethane into crystalline benzyl 4,6- O-benzylidene-α- d-glucopyranosido-(2,3:5′,6′)-2′-( R)-methyl-3′-morpholinone. Removal of the benzylidene group gave the crystalline 4,6-dihydroxy compound, characterized by a crystalline 4,6-diacetate and hydrogenolyzed into the amorphous title compound, which was characterized by a crystalline 1,4,6-tri- O-acetyl derivative. A similar series of transformations was applied to the β- d analog. In this series, the 4- O-acetyl, 6- O-acetyl, and 4- O-acetyl-6- O-trityl derivatives were obtained in addition to the 4,6-dihydroxy and 4,6-di- O-acetyl derivatives. The title compound is an important reference standard for the elucidation of the chemical structures of the cell wall of the bacterial spore.