novel 2 - acyl amino methyl - 5 - phenyl - 1h - 2 , 3 - dihydro - 1 , 4 - benzo diazepine compounds of the following formula i ## str1 ## which have valuable pharmacological properties are provided . in said formula i the acyl group -- co -- r 3 represents a benzoyl group or a phenyl alkanoyl group which may be unsubstituted or mono - or di - substituted in the phenyl ring . the substituent r 1 in said compounds indicates lower alkyl , lower alkenyl , or cyclopropyl methyl , and the substituent r 2 indicates hydrogen , lower alkyl , or lower alkenyl , while the substituent r 6 indicates hydrogen , halogen , lower alkyl , lower alkoxy , hydroxyl , lower alkylthio , nitro , trifluoro methyl , cyano , amino , mono - or di - lower alkyl amino , lower mono - alkanoyl amino , lower n - alkyl - n - alkanoyl amino , or lower alkanoyloxy , and the substituent r 7 indicates hydrogen , halogen , lower alkyl , lower alkoxy , hydroxyl , or lower alkanoyloxy , whereby r 6 and r 7 , when attached to adjacent carbon atoms , may form together the methylene dioxy or the ethylene dioxy group . the substituents r 8 and r 9 designate the same substituents as indicated for the substituents r 6 and r 7 . the compounds of formula i have a surprising analgesic activity .