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.
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 4JPH 1.13.
b Doublet of doublets; the coupling of this proton to the NH proton (3JHH) was not resolved well enough to measure.
c Doublet 4JPH 2.67.
a Base peak m/z 65.
a G represents a molecule of glycerol matrix.
b Base peak m/z 149.