How is (2S,4R)-4-(2-Cyanobenzyl)pyrrolidine-2-carboxylic acid hydrochloride (CAS: 1049743-86-3) typically synthesized?

(2S,4R)-4-(2-Cyanobenzyl)pyrrolidine-2-carboxylic acid hydrochloride can be synthesized via a multistep process involving the formation of a pyrrolidine ring and subsequent cyanobenzylation. The reaction is typically catalyzed by a palladium complex, and the yield is around 80-85%. The key steps include protection of the amino group, cyclization, and cyanobenzylation, followed by hydrolysis and acidification to form the hydrochloride salt.