Benzodiazepines are primarily used in medicine as tranquilizers. However, they also have been successfully used for epilepsy in controlling long-lasting convulsions. The most widely used is diazepam (5.1.2) and chlordiazepoxide (5.1.22). The synthesis of these was described in Chapter 5.
The third drug of the benzodiazepine family used for epilepsy is called clonazepam.
Clonazepam: Clonazepam, 5-(2-chlorphenyl)-1,3-dihydro-7-nitro-2H-1,4-benzodi-azepine-2-one (9.6.5), is synthesized by following a standard scheme of making derivatives of 1,4-benzodiazepines, with the exception that the acceptor nitrile group (in this example) on C7 of the benzodiazepine system is introduced at the last stage of synthesis. The synthesis of clonazepam begins with 2-chloro-2'nitrobenzophenon, which is reduced to 2-chloro-2'-aminobenzophenon (9.6.1) by hydrogen over Raney nickel. The amino derivative is amidated by 2-bromoacetyl bromide to give the bromacetamide (9.6.2) and is further converted into aminoacetamide (9.6.3) upon reaction with ammonia. Upon reaction this with pyridine, it is cycled into 5-(2-chlorophenyl)-2,3-dihydro-1H-1,4-benzodi-azepine-2-one (9.6.4). The nitration of the resulting product in mild conditions (potassium nitrate in sulfuric acid) results in clonazepam (9.6.5) [18-23].
Was this article helpful?