Distal effect on mass spectral fragmentations of glycolamide esters of 6-methoxy-2-naphthylacetic acid (6-MNA) and the crystal structure of N,N'-dimethyl-glycolamide ester of 6-MNA

The spatial proximity allows facile glycolamide ((HOCH2CONRR2)-R-1) loss from 6-methoxy-2-naphthylacetic acid (6-MNA) glycolamide esters in their mass spectra. The process occurs through a hydrogen rearrangement followed by a charge initiated C-O bond cleavage to give 6-methoxy-2-naphthyl ketene radical cation (m/z 198). However, this fragment ion is completely absent in the mass spectra of various alkyl ester of 6-MNA indicating that in spite of structural similarity between these two types of derivatives, the fragmentation pattern of glycolamide esters is influenced remotely by amide functionality. X-ray studies of N, N - dimethyl derivative indicate that probably, the specific conformation adopted by the molecule has decisive role to play in the observed fragmentation pattern.