How is Tetrahydro-2H-thiopyran-4-carboxylic acid (CAS: 89489-53-2) typically synthesized?

Tetrahydro-2H-thiopyran-4-carboxylic acid can be synthesized via the hydrolysis of thiopyranone using a weak acid catalyst, such as hydrochloric acid. The reaction typically proceeds with a yield of around 70-80%, and the product is isolated by recrystallization from an appropriate solvent. Other methods include the condensation of acetic acid and thiophene, followed by further transformations to obtain the desired carboxylic acid.