2-deoxy-1,3,4,5,6-penta-O-methyl-2-(N-methylacetamido)-d-glucitol and derivatives undergo C-emthylation at the N-methylacetamido group on repeated hakomori methylation

Abstract After Hakomori methylation of 2-acetamido-2-deoxy- d -glucitol, the expected 2-deoxy-1,3,4,5,6-penta- O -methyl-2-( N -methylacetamido)- d -glucitol ( 3 ) was identified by g.l.c.-m.s. as the major product, and two minor products, 2-acetamido-2-deoxy-1,3,4,5,6-penta- O -methyl- d -glucitol ( 2 ) 2-deoxy-1,3,4,5,6-penta- O -methyl-2-( N -methylpropionamido)- d -glucitol ( 4 ), were present. The proportions and yields of these products were dependent on the reagent (sodium or potassium hydride) used for the preparation of the methylsulfinylmethanide. On Hakomori methylation of 2 and 3 , the N -methylpropionamido ( 4 )-methylisobutyramido, and traces of the N -methylpivalamido derivatives of 2-deoxy-1,3,4,5,6-penta- O -methyl- d -glucitol were formed. Using trideuteriomethyl iodide for methylation ( e.g. , of 3 ), it was found by g.l.c.-m.s. that the newly introduced methyl group(s) were located at the β-carbon of the N -methylacetamido group. Analogous results were obtained with 2-deoxy-4- O -[2[deoxy[3,4,6-tri- O -methyl-2-( N -methylacet-amido)-β- d -glucopyranosyl]-1,3,5,6,-tetra- O -methyl- 2-( N -methylacetamido)- d -glucitol.