1H-1H Long range couplings in fused cyclopropanes. NMR spectral assignment and conformation of 17,18-cyclosteroids
1H-1H NMR couplings through four bonds ( 4JH-H) involving cyclopropane hydrogens were calculated for model compounds by semiempirical methods and used for the 13C and 1H NMR spectral assignment of 17,18-cyclosteroids. The couplings (4JHH) between cyclopropyl and non-cyclopropyl hydrogens follow an a...
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| Autores principales: | , , , |
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| Formato: | JOUR |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_03009580_v5_n_p933_Sproviero |
| Aporte de: |
| Sumario: | 1H-1H NMR couplings through four bonds ( 4JH-H) involving cyclopropane hydrogens were calculated for model compounds by semiempirical methods and used for the 13C and 1H NMR spectral assignment of 17,18-cyclosteroids. The couplings (4JHH) between cyclopropyl and non-cyclopropyl hydrogens follow an angular dependence which resembles that of allylic couplings. Solution conformations of rings C-D and the side-chain of 17,18-cyclopregnanes were determined from semiempirical molecular orbital calculations, three and four bond 1H-1H coupling constants and NOE measurements. |
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