X-ray photoelectron spectra study on the derivatives of N-beta-phenethyl amine and N-beta-phenethyl glycine.

ABSTRACT

The X-ray photoelectron spectra of sixteen derivatives of N-beta-phenethyl amine and N-beta-phenethyl glycine have been studied. The effect of different structures on N1s binding energy and that of their Pauling's atomic charge density on the nitrogen atoms are investigated. The experimental binding energy of N1s is proportional to the calculated Pauling's atomic charge density. It shows that the phosphoryl group is the strongest nitrogen lone pair electron localizing group as compared with the corresponding sulfonyl and acyl derivatives. The XPS results agree with the data that there is no decarbonylation during the synthesis of N-dialkylphosphoryl-tetrahydro-3-benzazepin-1-one. In addition, since the N1s in P-N bond is smaller than that in S-N and C-N bonds, the phosphoryl group can be removed under much milder conditions. These results provide a semi-empirical evidence for the synthesis of the skeleton of the cephalotaxine. It also differentiates the reaction paths for these three different amino protecting groups.