NUCLEAR MAGNETIC-RESONANCE OF 1,4-BENZODIAZEPINES .2. STEREOCHEMISTRY OF 1,3-DIHYDRO-2H-1,4-BENZODIAZEPIN-2-ONES BY LANTHANIDE SHIFT-REAGENTS

The sterochemistry of some 1,3‐dihydro‐2H‐1,4‐benxodiazepin‐2‐ones, employed as psychotherapeutic agents, is deduced by proton magnetic resonance using the paramagnetic shift reagent Eu(fod)3. the lanthanide induced shifts are computer simulated on the basis of the geometric parameters of the protons in different model structures, having intermediate conformations between a cycloheptadiene‐ and a cyclohepatatriene‐like system. N‐Desmethyldiazepam shows a conformational equilibrium between two pseudoboat forms, while the 1‐alkyl substituted derivatives exist, at room temperature, in olny one boat cycloheptatriene‐like conformation. Copyright © 1979 Heyden & Son Ltd.