A METHOD FOR THE PREPARATION OF 6,7-DIMETHOXY-1-[2-(4-TRIFLUOROMETHYLPHENYL)ETHYL]-3,4- DIHYDROISOQUINOLINE

摘要

The invention relates to a method of preparing 6,7-dimethoxy-l-[2-(4-trifluoromethylphenyl) ethyl]-3,4-dihydroisoquinoline I by cyclization of substance III, wherein the R substituent is a C1-C4 alkyl group, under conditions of acidic catalysis, the acidic catalyst being a strong inorganic acid, polyphosphoric acid or phosphorus oxychloride. The compound of formula (I) represents the key intermediate of synthesis of almorexant. (Formulae (I), (III))