Diazepam, better known as Valium, is a central nervous

Chapter 22, Problem 23.52

(choose chapter or problem)

Diazepam, better known as Valium, is a central nervous system (CNS) sedative/hypnotic. As a sedative, it diminishes activity and excitement and thereby has a calming effect. In 1976, based on the number of new and refi lled prescriptions processed, diazepam was the most prescribed drug in the United States. Following is a retrosynthetic analysis for a synthesis of diazepam. Note that the formation of compound B involves a Friedel-Crafts acylation. In this reaction it is necessary to protect the 2 amine by prior treatment with acetic anhydride. The acetylprotecting group is then removed by treatment with aqueous NaOH followed by careful acidifi cation with HCl. Me Cl N O Diazepam 4- Chloro-N-methylaniline Benzoyl chloride N Me Cl Cl Cl N O (A) O (B) O Me Cl N H Me O Cl N H 1 1 2 3 (a) Given this retrosynthetic analysis, propose a synthesis for diazepam. (b) Is diazepam chiral? If so, how many of the possible stereoisomers are formed in this synthesis?