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-α-substituted-2H-isoindo­le-2-acetic acid derivatives of phenylboronic acid of compo­sitions PhBOH[O2CCH(R)C(O)] and PhB[O2CCH (R)(O)]2 [where -CH(R)=-CH2CH2-, R=-CH2­­C6H5, -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. 11B NMR data reveal the presence of tetracoordinated boron centers in these N-protected amino acid derivatives of phenylboronic acid.