An anesthetic is a drug that causes reversible loss of sensation. They contrast with an*lgesics (painkillers), which relieve pain without eliminating sensation. These drugs are generally administered to facilitate surgery.

Cocaine (benzoylmethylecgonine)...
is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. It is a stimulant of the central nervous system, an appetite suppressant, and a topical anesthetic.

FormulaC17H21NO4,
Systematic (IUPAC) name
methyl (1R,2R,3S,5S)-3- (benzoyloxy)-8-methyl-8-azabicyclo[3.2.1] octane-2-carboxylate
Melt. point98 C (208 F)
Boiling point187 C (369 F)
Solubility in waterHCl: 1800-2500 mg/mL (20 C)

Biosynthesis of cocaine
The additional carbon atoms required for the synthesis of cocaine are derived from acetyl-CoA, by addition of two acetyl-CoA units to the N-methyl-&916;1-pyrrolinium cation.

The first addition is a Mannich-like reaction with the enolate anion from acetyl-CoA acting as a nucleophile towards the pyrrolinium cation. The second addition occurs through a Claisen condensation. This produces a racemic mixture of the 2-substituted pyrrolidine, with the retention of the thioester from the Claisen condensation. In formation of tropinone from racemic ethyl [2,3-13C2]4(Nmethyl-2-pyrrolidinyl)-3-oxobutanoate there is no preference for either stereoisomer.

In the biosynthesis of cocaine, however, only the (S)-enantiomer can cyclize to form the tropane ring system of cocaine. The stereoselectivity of this reaction was further investigated through study of prochiral methylene hydrogen discrimination.

This process occurs through an oxidation, which regenerates the pyrrolinium cation and formation of an enolate anion, and an intramolecular Mannich reaction. The tropane ring system undergoes hydrolysis, SAM-dependent methylation, and reduction via NADPH for the formation of methylecgonine. The benzoyl moiety required for the formation of the cocaine diester is synthesized from phenylalanine via cinnamic acid.

Benzoyl-CoA then combines the two units to form cocaine.