Chloroprocaine is used in situations requiring fast-acting pain relief. It is also used in infiltration anesthesia, blocking peripheral nerve transmission, and in spinal and epidural anesthesia. Nesacaine is a synonym for chloroprocaine.
Tetracaine: Tetracaine, the 2-diethylaminoethyl ester of 4-butylaminobenzoic acid (2.1.6), is also structurally analogous to procaine, in which the amino group of the benzene ring is replaced by a butylamine radical. The methods for its synthesis are the same as the above-mentioned methods for procaine or chloroprocaine, with the exception of using 4-butylaminobenzoic acid in place of 4-aminobenzoic acid. There is also a proposed method of synthesis that comes directly from procaine (2.1.1). It consists on its direct reaction with butyric aldehyde and simultaneous reduction by hydrogen using a palladium on carbon catalyst .
Tetracaine is a strong, long-lasting local anesthetic. It is primarily used in spinal cord anesthesia. The most well-known synonyms of tetracaine are pontocaine and butylcaine.
Cocaine: Cocaine, 3-/¡-benzoyloxy-2/¡-(2.1.13) can be considered the practical, and in a certain sense, the ideological ancestor of anesthetics of the aminoester series. The alkaloid cocaine was isolated in 1860 from leaves of the cocaine shrub (Erthroxylon coca), which contains various alkaloids that are ecogonic derivatives (2.1.11), of which cocaine makes up a significant portion. Its structure was established in 1898. The main part of obtaining cocaine is synthesized in a semisynthetic manner. By saponification of a number of alkaloids extracting from coca leaves, ecogonin is obtained (2.1.11), carboxylic group of which is methylated which gives the methyl ester of ecogonin (2.1.12). The hydroxyl group of the obtained product is further benzoylated, which gives cocaine (2.1.13). The process of these conversions corresponds with the final part of the first scheme of cocaine synthesis.
The first synthesis of cocaine was proposed in 1902. The two subsequent schemes could be considered the most rational of the proposed choices for cocaine synthesis. The first figure shows the cocaine synthesis which starts from the potassium salt of the acetonedicar-bonic acid ethyl ester, which upon electrolysis gives the diethyl ester of succinyldiacetic acid (2.1.7), which upon further reaction with methylamine forms 1-methyl-2,5-dicar-bethoxymethyldenepyrrolidin (2.1.8). Reduction of the two double bonds in this compound leads to the formation of 1-methyl-2,5-dicarboethoxymethylpyrrolidine (2.1.9). This undergoes intermolecular Dieckman cyclization using sodium ethoxide as a condensing agent, which gives the ethyl ester of tropin-2-carboxylic acid (2.1.10). Reduction of the keto group and final hydrolysis of the carboethoxy group gives tropin-2-carboxylic acid, or ecogonin (2.1.11). Methylation of the carboxyl group to an ester (2.1.12) and further esterification of the hydroxyl group by benzoyl chloride leads to a racemic mixture of 3-benzoyl-2-methoxycarbonyltropane (2.1.3), from which d,l-cocaine was isolated. The separation of optical isomers is accomplished through the transformation to d-bromocamphor-^-sulfonic
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