An efficient synthesis of 1-(naphthalen-1-yl) ethanamine (RS-2) and its practical resolution to optically pure (1 R)-(naphthalen-1-yl) ethanamine (R-(+)-2), a key intermediate in the synthesis of cinacalcet hydrochloride (1), is described. The resolution of RS-2 using R-(−)- mandelic acid as a resolving agent in ethanol was established on an industrial scale to give pure R-(+)-2 with> 99.8% ee after liberation of the amine from its mandelate salt. An ...