4-bromo-1-naphthonitrile was obtained by a new route of bromo-magnesium exchanging reaction, synthesis and dehydration of 4-bromo-1-naphthamide using 1,4-dibromonaphthalene as starting materials. The Miyaura borylation of 4-bromine-1- naphthonitrile and its Suzuki coupling with ethyl 2-(3-bromopyridine-4-yl)thio-2-methylpropionate were realized using Pd(PPh3)2Cl2 as catalyst by a continuous reaction method. The conditions for coupling reaction and the hydrolysis of the product to produce RDEA3170 were optimized. The overall yield of RDEA3170 is 42% and the optimized synthetic process is suitable for the industrial production.