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Carbon‐13 NMR of tertiary fluorosteroids as a stereochemical probe
Author(s) -
Rozen Shlomo,
BenShushan Giora
Publication year - 1985
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260230213
Subject(s) - chemistry , fluorine , halogen , coupling constant , chemical shift , fluorine 19 nmr , carbon fibers , carbon 13 nmr , carbon atom , atom (system on chip) , nuclear magnetic resonance spectroscopy , stereochemistry , organic chemistry , ring (chemistry) , alkyl , physics , materials science , particle physics , composite number , computer science , composite material , embedded system
The 13 C NMR spectra of tertiary fluorinated steroids possessing no functional groups in the vicinity of the fluorine have been measured. All α‐ and β‐carbons are deshielded by the fluorine atom. The γ‐carbons, however, are divided into two groups. The carbons gauche to the fluorine atom are all shielded by 1–8 ppm, whereas the γ‐carbons anti to the halogen are all deshielded by 2–5 ppm. Apart from the α‐Carbons, which have coupling constants of 170–180 Hz, all β‐Carbons are also coupled to the fluorine with a 2 J (CF) value of approximately 20 Hz. The γ‐carbons gauche to the fluorine have a very small coupling constant (usually 0‐3 Hz), while the anti γ‐carbons are split by the fluorine by 6–8 Hz. Both chemical shifts and coupling constants can be used for the Stereochemical evaluation of fluorosteroids.