Quinazolines et benzodiazépines‐1, 4. LVI. Oxadiazolo‐1, 2, 4[4, 5‐d] benzodiazépines‐1, 4: synthése et passage aux oxazolo [3, 2‐d] benzodiazépines‐1, 4

The tricyclic derivatives 4–14 can be prepared by 1, 3‐dipolarcycloaddition of the appropriate nitrile oxides on the corresponding 1, 4‐benzodiazepines. NaBH 4 reduction of the esters 12–14 was found to proceed very readily; starting from 13 it is possible, by proper reaction conditions, to get in good yield either the monoalcohol 19 or the aminodiol 20 . The alcohols 19 and 23 undergo an acid‐catalysed rearrangement which produces the amidoximes 24 and 26 . The determination of the structure of 24 by X‐ray diffraction analysis is also presented.