Some new N-protected amino acid derivatives of phenylboronic acid: preparation, structural chemistry and insight into structural aspects based on spectroscopic studies

Some new 1,3-dihydro-1,3-dioxo-alpha-substituted-2H-isoindole-2-acetic acid derivatives of phenylboronic acid of compositions PhBOH[O2CCH(R)NC(O)C6H4C(O)] and PhB[O2CCH (R)NC(O)C6H4C(O)](2) [where-CH(R)=-CH2CH2-, R=-CH2-C6H5,-CH(CH3)(2), and -CH(CH3)C2H5] have been prepared by the reaction of phenylboronic acid with N-protected amino acids in 1:1 and 1:2 molar ratios in dry refluxing benzene. Plausible structures of these newly synthesized N-protected amino acid derivatives of phenylboronic acid have been proposed on the basis of physicochemical and spectroscopic studies. B-11 NMR data reveal the presence of tetracoordinated boron centers in these N-protected amino acid derivatives of phenylboronic acid.