Chirality 1997-01-01

Synthesis and chiroptical properties of a novel C2-symmetric binaphthyl phosphortriamide ("chiral HMPA").

A I Meyers, T Nguyen, D Stoianova, N Sreerama, R W Woody, A Koslowski, J Fleischhauer

Index: Chirality 9(5-6) , 431-4, (1997)

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Abstract

By use of an asymmetric Ullmann coupling involving chiral naphthalene oxazolines 1, the title compounds were prepared in good yields and with high diastereoselectivity. Hydrolysis of the binaphthyl oxazolines 2 led to the di-aldehydes 5, which were transformed into the azepine derivative, 6. The latter was treated with the appropriate phosphoryl halide to access the chiral HMPA systems 7 and 9. The CD spectra of the chiral azepine 6 and the chiral phosphoramides 7 and 9 were measured and showed a strong positive CD couplet near 225 nm, consistent with the P axial chirality (S configuration). Semi-empirical CNDO/S molecular orbital calculations of the CD spectrum of 6 satisfactorily reproduced the major features of the observed spectrum.