Boron trifluoride → 3-(4-Cyano-4-(3,4-dimethoxyphenyl)-5-methylhex-1-yl)-1,2,3,4-tetrahydro-6,7-dimethoxy-2-methylisoquinoline

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Reaction Steps

The ammonium compound of formula 29 is then cyclized to form a compound of formula 1 (step 7). This reaction is performed using 1-1.5 moles of a Lewis acid, such as AlCl3, FeCl3, BF3, and the like, in a suitable aprotic solvent, preferably a halogenated hydrocarbon solvent, nitromethane, or nitrobenzene, particularly CH2Cl2, at a temperature of about -10° to about 80° C., for a period of about 10 minutes to about five hours, preferably about two hours. For example, N-[1-chloro-6-(3,4-dimethoxyphenyl)-6-cyano-6-(prop-2-yl)hex-2-yl]-N-(3,4-dimethoxybenzyl)-N-methylammonium chloride (29) is suspended in CH2Cl2 at 0° C. and stirred with 1.5 moles of AlCl3 for 2 hours to produce 3-[4-(3,4-dimethoxyphenyl)-4-isopropyl-4-cyanobutyl]-6,7-dimethoxy-N-methyl-1,2,3,4-tetrahydroisoquinoline (1).

Provenance & Evidence