1-AMINO-1-ARYL- AND 1-AMINO-1-HETEROARYL-METHANEPHOSPHONIC ACIDS AND THEIR N-BENZHYDRYL–PROTECTED DIETHYL ESTERS: PREPARATION AND CHARACTERIZATION

Abstract

n-Benzhydryl-protected diethyl[3.3pc] esters of 1-amino-1-aryl- (phenyl, cumyl, p-dimethylaminophenyl, piperonyl, 1′-naphthyl, 9′-anthryl, 1′-pyrenyl) and 1-amino-1-heteroaryl- (furyl, 2′-thienyl, 3′-thienyl, 2′-pyrrolyl)-methanephosphonic acids, prepared by the addition of diethyl phosphite to the corresponding benzhydryl imines, have been isolated, purified, and characterized. The presence of chiral α -carbon and prochiral phosphorus in these esters gives rise to complicated features in their NMR spectra, which are discussed. Hydrolysis of the crude 1-aryl compounds in situ gave modest yields of the corresponding aminophosphonic acids (except for 1′-pyrenyl). Of the 1-heteroaryl derivatives, only the 2′-thienyl compound gave the expected aminophosphonic acid; in other cases, alternative[-18pc] modes of decomposition may occur under hydrolytic conditions. NMR and mass spectral data are given for all products.

Keywords:

• Aminophosphonate
• aminophosphonic acids
• aryl
• heteroaryl
• mass spectrometry
• NMR

We thank the Higher Education Funding Council for England (HEFCE) for financial support of a studentship (for R. J. Lee) and Prof. Dr. Gerhard Hägele of the Heinrich-Heine-Universität, Düsseldorf, for helpful discussions. We are grateful to Mr. John Crowder for assistance with nmr spectroscopy, Mr. Wimal Dissanayake for recording the mass spectra, and Mr. S. Boyer for microanalysis.

Notes

^a Doublet ⁴J_PH 1.13.

^b Doublet of doublets; the coupling of this proton to the NH proton (³J_HH) was not resolved well enough to measure.

^c Doublet ⁴J_PH 2.67.

^a Base peak m/z 65.

^a G represents a molecule of glycerol matrix.

^b Base peak m/z 149.