Benzodiazepine derivatives are a basic class of anxiolytics or tranquilizers—compounds for treating conditions of general anxiety, and their synthesis and properties as such will be considered separately. However, despite the fact that the principal clinical effect of the benzodiazepines used in medicine is basically qualitatively identical, certain benzodiazepines are used for specific purposes other than relieving anxiety. In particular, representatives of this series of benzodiazepines such as flurazepam, temazepam, and triazolam are used as hypnotics, while clonazepam is used as an anticonvulsant drug. Moreover, the most pharmacologically effective drugs presently used for treating sleep disturbances are flurazepam, temazepam, and triazolam. However, in small doses the above hypnotics are sedative drugs. It is believed that their primary action consists of alleviation of psychological anxiety, the resulting calmness of which facilitates development of sleep. The mechanism of action of benzodiazepines is related to their interaction with specific benzodiazepine receptors, considering that as a result of binding, the affinity of inhibitory GABA neurotransmitters to their respective receptors is increased, which strengthens the inhibitory action of the GABA. The examined drugs flurezepam, temazepam, and triazolam evidently raise the inhibitory effect of GABA on the CNS.
Triazolam: Triazolam, 8-chloro-6-(2'-chlorophenyl)-1-methyl-4-H-s-triazolo[4,3-a]-[1,4]benzodiazepine (4.2.4), is synthesized according to a method that contains a key stage of benzodiazepine synthesis—the reaction of o-aminobenzophenones with a-amino acid derivatives. In the given example, the reaction of 2-amino-2',5-dichlorobenzophenone with glycine ethyl ester gives 7-chloro-5-(2-chlorophenyl)-2,3-dihydro-1-H-1,4-benzodiazepin-2-one (4.2.1). By interacting this with phosphorus pentasulfide, the carbonyl group is transformed into a thiocarbonyl group, giving 7-chloro-5-(2-chlorophenyl)-2,3-dihydro-1-H-1,4-benzodiazepin-2-thione (4.2.2). The resulting cyclic thioamide on interaction with acetylhydrazine, gives the corresponding acetylhydrazone (4.2.3), which upon heating cyclizes into triazolam (4.2.4) [15-20].
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