| abstract |
The invention provides a process for preparing 1-methyl-1,2,3,4-tetrahydroisoquinoline of formula (A), or a salt thereof, the process comprising: (i) reacting N-(2-chloroethyl)-α-methylbenzylamine of formula (B), or a salt thereof, with a Lewis acid such as AlCl3, and (ii) causing or allowing cyclisation to 1-methyl-1,2,3,4-tetrahydroisoquinoline. The invention also provides a process for preparing 1-methyl-1,2,3,4-tetrahydroisoquinoline of formula (A), or a salt thereof, the process comprising: (i) reacting a N-(2-haloethyl)-α-methylbenzylamine, or a salt thereof, with a Lewis acid and (ii) causing or allowing cyclisation to 1-methyl-1,2,3,4-tetrahydroisoquinoline at a temperature of ≤130°C. The use of N-(2-chloroethyl)-α-methylbenzylamine and/or lower cyclisation temperatures decreases the amount of certain impurities formed in the reaction. In other aspects of the invention, the 1-methyl-1,2,3,4-tetrahydroisoquinoline can be used in the synthesis of 5,6-dimethyl-2-(4-fluorophenylamino)-4-(1-methyl-1,2,3,4-tetrahydroisoquinolin-2-yl)pyrimidine (SB 641257, YH1885), a pharmaceutically active reversible proton pump inhibitor. |