Dimethyl esters of 1-amino-2-arylmethyl cyclohexyl phosphonic acids. Synthesis and NMR characterization

Dimethyl esters of amino-arylmethyl phosphonic acids containing a cyclohexyl moiety have been prepared in good yields. All compounds are white crystalline powders very soluble in low boiling point organic solvents. Characterization by H-1-NMR techniques indicates that ortho substituents shift downfield the CH resonance, whereas ortho-carboxy groups, through hydrogen bonding with the NH group, yield a cyclic structure responsible of the dramatic downfield shift of the NH resonance.