Construction of 3-arylpropylamines using Heck arylations. The total synthesis of cinacalcet hydrochloride, alverine, and tolpropamine

New synthetic routes toward the commercial drugs cinacalcet hydrochloride, alverine, and tolpropamine were developed using a Heck-Matsuda arylation as the key-step. Several reaction conditions were evaluated for the Heck-Matsuda reaction using allylamine derivatives and arenediazonium salts. For cinacalcet hydrochloride, N-formylamide provided the best result, furnishing the synthetic target in a very high overall yield (75% over five steps). For alverine, the best results were obtained using a double Heck-Matsuda strategy, providing alverine in an excellent overall yield (69%) from N-acetyl diallylamine in three steps. Tolpropamine was synthesized in a 46% yield over five steps using an efficient reductive Heck-Matsuda arylation between p-bromo-methylcinnamate with 3-chloro tolyldiazonium salt, generating the β,β-diaryl propionate that was converted to tolpropamine.