[The behavior of 1,4-benzodiazepine drugs in acidic media. XVI. Estimation of cis/trans isomer ratio of benzodiazepinooxazoles using nuclear magnetic resonance shift reagent].
The ratio of cis/trans isomers (referring to 11b-substituent and 2- or 3-substituent) of benzodiazepinooxazoles was estimated by using the lanthanide shift reagent (Eu(fod)3-d27) for nuclear magnetic resonance (NMR) spectroscopy. The amide carbonyl oxygen at 6-position is considered to coordinate with the reagent, because the largest downfield shifts were observed at the amide carbonyl carbon (C-6) in 13C-NMR and the amide hydrogen (H-7) in 1H-NMR. The ratios depend largely on the substituents at 11b-, 2-, and 3-positions. The cis isomer for compounds having 11b-hydrogen increases with an increase in the bulkiness of the substituents at 2-position. The cis isomer for compounds having 3-methyl group decreases with change from 11b-2'-chlorophenyl group (mexazolam) to 11b-hydrogen.
Kuwayama
T
T
Department of Pharmacy, NTT Tokai General Hospital, Nagoya, Japan.
Kato
S
S
Kurono
Y
Y
Hatano
K
K
Hayazaki
T
T
Yashiro
T
T
Ikeda
K
K
D001569:Benzodiazepines / Q000737:chemistry*; D002725:Chloroform; D007202:Indicators and Reagents; D007536:Isomerism; D007811:Lanthanum; D009682:Magnetic Resonance Spectroscopy
D007202:Indicators and Reagents; D001569:Benzodiazepines; D007811:Lanthanum; D002725:Chloroform