Starting from 3-hydroxy-1,4-benzodiazepin-2-ones 1--3, via 3-chloro derivatives 4--6, 13 new C(3)-substituted 1,4-benzodiazepin-2-ones were synthesized. Reaction of 4--6 with ethylene glycol yielded 3-(beta-hydroxyethyl) derivatives 7--9. Similar reaction with the isopropylidene derivative of glycerol afforded 10--12, which on hydrolysis of the isopropylidene group hielded glycerol derivatives 13--15. Reaction of trichloroacetyl chloride with oxazepam and temazepam yielded the corresponding trichloroacetyl esters 16 and 17. The beta-hydroxyethyl derivative 7 was conjugated with an acetylated glucopyranose derivative to give isomeric 18 and 19. Partition coefficients (log Poct) and central nervous system activities (in six stranded tests) were determined for 7--15 as well as several standard compounds. Most of the compounds exhibiting beneficial central nervous system activity had Poct values between 1.71 and 2.48. No correlation between lipophilicity and central nervous system activity could be discerned for these compounds.