Hydrochloric Acid → 6,7-Dimethoxy-1-[4-(2-methoxypyridin-3-yl)benzyl]-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester

Participants

Reaction Steps

6,7-Dimethoxy-1-[4-(2-methoxypyridin-3-yl)benzyl]-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester 6 was synthesized by the Suzuki coupling of 1-(4-bromobenzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester 1 with 2-methoxypyridine-3-boronic acid 5 using Palladium(II) acetate, triphenylphosphine, and Na2CO3 in anhydrous isopropanol. Compound 6 was treated with 2 M HCl solution in diethylether to get 6,7-dimethoxy-1-[4-(2-methoxypyridin-3-yl)benzyl]-1,2,3,4-tetrahydroisoquinoline hydrochloride salt 7. Reaction of 7 with formaldehyde in the presence of sodium cyanoborohydride, and zinc chloride furnished 6,7-dimethoxy-1-[4-(2-methoxypyridin-3-yl)benzyl]-2-methyl-1,2,3,4-tetrahydro-isoquinoline 8 which was treated with 2 M HCl solution in diethylether to obtain 6,7-dimethoxy-1-[4-(2-methoxypyridin-3-yl)benzyl]-2-methyl-1,2,3,4-tetrahydro-isoquinolinehydrochloride 9 (Scheme-2).

Provenance & Evidence