Propose a synthesis of the topical anesthetic cyclomethycaine from 4-hydroxybenzoic acid and 2-methylpiperidine and any other necessary reagents.

First, let's identify the functional groups present in both the starting materials (4-hydroxybenzoic acid and 2-methylpiperidine) and cyclomethycaine. 4-hydroxybenzoic acid consists of a carboxylic acid (\(\ce{COOH}\)) group and a hydroxyl (\(\ce{OH}\)) group attached to a benzene ring. 2-methylpiperidine consists of a secondary amine group (\(\ce{NH}\)) attached to a heterocyclic 6-membered ring with one nitrogen atom (piperidine) and an additional methyl group (\(\ce{CH3}\)) at the second position. Cyclomethycaine consists of an ester group (\(\ce{COOR}\)) connecting the benzene ring and the piperidine ring. We will need to synthesize the amide linkage between these two groups while keeping the rest of the structure intact.

Now that we have identified the functional groups present in the starting materials and cyclomethycaine, we can plan a suitable synthetic route. One possible strategy is as follows: 1. Convert the carboxylic acid group of 4-hydroxybenzoic acid into an acid chloride using an appropriate reagent, such as thionyl chloride (\(\ce{SOCl2}\)). 2. Perform a nucleophilic substitution reaction between the acid chloride and the secondary amine group in 2-methylpiperidine to form the ester linkage.

1. Conversion of carboxylic acid to acid chloride: Treat 4-hydroxybenzoic acid with thionyl chloride (\(\ce{SOCl2}\)) to convert the carboxylic acid group into an acid chloride. The reaction can be performed at reflux temperature under an inert atmosphere, and the byproducts (\(\ce{SO2}\) and \(\ce{HCl}\)) can be removed by simple distillation. 2. Formation of ester linkage: In a separate flask, add the acid chloride obtained in the previous step to a solution containing 2-methylpiperidine. The reaction temperature should be kept cool to prevent side reactions from occurring. The secondary amine in 2-methylpiperidine will act as a nucleophile, attacking the carbonyl carbon of the acid chloride, thus forming the ester linkage between the benzene and piperidine rings. 3. Isolation of the product: After the completion of the reaction, the resulting mixture should be washed with a dilute acid solution to protonate any unreacted amine, followed by extraction with an organic solvent to separate the cyclomethycaine product. Further purification methods, such as recrystallization or chromatography, can be employed to obtain the pure cyclomethycaine.