Carbon-13 nuclear magnetic resonance spectroscopy of C/D-cis polyoxypregnanes. I

✍ Scribed by Takashi Yamagishi; Koji Hayashi; Hiroshi Mitsuhashi; Mamoru Imanari; Kazuhiro Matsushita

• Book ID: 104238296
• Publisher: Elsevier Science
• Year: 1973
• Tongue: French
• Weight: 191 KB
• Volume: 14
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)86961-6

✦ Synopsis

Carbon-13 NMR spectra of about 40 polyoxypregnanes were determined at 25.146 MHz on a Pulsed FT NMR spectrometer (1). C-13 NMR spectra have been far more informative than proton NMR spectra for structural analyses of the C/D-cis polyoxypregnanes,* both because of the enormous sensi-tivity of C-13 chemical shifts to structural changes and because of large differences in chemical shifts (the order of ca. 200 ppm). All of the skeletal atoms of the polyoxypregnanes were assigned by the techniques such as noise-modulated total proton decoupling (Fig. la), off-resonance proton decoupling (Fig. lb), and substituent influences on chemical shifts in analogous compounds. Carbons in ring A and B are assignable by comparison with the spectra of cynanchogenin (Ib) and . I C-13 NMR analyses for other steroids were refered to the following article: K. Tori,