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

✍ Scribed by A. I. Meyers; Thanh Nguyen; Diana Stoianova; N. Sreerama; Robert W. Woody; Axel Koslowski; Jörg Fleischhauer

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 90 KB
• Volume: 9
• Category: Article
• ISSN: 0899-0042
• DOI: 10.1002/(sici)1520-636x(1997)9:5/6<431::aid-chir6>3.0.co;2-8

✦ Synopsis

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.