Chapter 21, Problem 73P

(a) Why are alkyl halides insoluble in water? (b) Why is Butan-l-ol optically inactive but Butan-2-ol is optically active? (c) Although chlorine is an electron withdrawing group, yet it is ortho-, Para- directing in electrophilic aromatic substitution reaction. Why?

A key step in the synthesis of the narcotic analgesic meperidine (trade name Demerol) is the conversion of phenylacetonitrile to X. (a) What is the structure of X? (b) What reactions convert X to meperidine?

(−)-Hyoscyamine, an optically active drug used to treat gastrointestinal disorders, is isolated from Atropa belladonna, the deadly nightshade plant, by a basic aqueous extraction procedure. If too much base is used during isolation, optically inactive material is isolated. (a) Explain this result by drawing a stepwise mechanism. (b) Explain why littorine, an isomer isolated from the tailflower plant in Australia, can be obtained optically pure regardless of the amount of base used during isolation.

Which compound will undergo nucleophilic aromatic substitution faster when treated with CH3NH₂? (a) CI (b) CI

Safrole, which is isolated from sassafras (Problem 21.33), can be converted to the illegal stimulant MDMA (3,4-methylenedioxymethamphetamine, "Ecstasy") by a variety of methods. (a) Devise a synthesis that begins with safrole and uses a nucleophilic substitution reaction to introduce the amine. (b) Devise a synthesis that begins with safrole and uses reductive amination to introduce the amine. NHCH9 MDMA safrole

Januvia, the trade name for sitagliptin, was introduced in 2006 for the treatment of type 2 diabetes. (a) Explain why the five-membered ring in sitagliptin is aromatic.

(a) Draw two different halo ketones that can form A by an intramolecularalkylation reaction. (b) How can A be synthesized by an acetoacetic estersynthesis?

(a) Draw two different halo ketones that can form A by an intramolecular alkylation reaction. (b) How can A be synthesized by an acetoacetic ester synthesis? of A

(a) Draw all products formed by treatment of each dibromide (A and B) with one equivalent of NaNH2. (b) Label pairs of diastereomers and constitutional isomers.