3(2H)-Pyridazinone → 2-{6-[2-(2-methyl-pyrrolidin-1-yl)-ethyl]-naphthalen-2-yl}-2H-pyridazin-3-one

Participants

Reaction Steps

One process for the preparation of 2-{6-[2-(2-methyl-pyrrolidin-1-yl)-ethyl]-naphthalen-2-yl}-2H-pyridazin-3-one, which demonstrates activity as a histamine-3 receptor ligand, involves treating an inexpensive and readily available starting material, 6-bromo-naphthalen-2-ol, to afford 2-{6-[2-(2-methyl-pyrrolidin-1-yl)-ethyl]-naphthalen-2-yl}-2H-pyridazin-3-one. Briefly, the process involves providing 6-bromo-naphthalen-2-ol. Preparing the triflate, or trifluoromethansulfonic acid ester, of 6-bromo-naphthalen-2-ol (2) with trifluoromethanesulfonic anhydride or another suitable trifluoromethanesulfonic reagent. The resulting trifluoro-methanesulfonic acid 6-bromo-naphthalen-2-yl ester (2) is converted to 2-bromo-6-vinyl-naphthalene (3) via a Pd-catalyzed Suzuki cross-coupling reaction. The 2-bromo-6-vinyl-naphthalene is reacted with a 2-methylpyrrolidine anion generated with n-butyllithium to provide 1-[2-(6-bromo-naphthalen-2-yl)-ethyl]-2-methyl-pyrrolidine (4). Compound (4) is reacted with 2H-pyridazin-3-one to provide the desired 2-{6-[2-(2-methyl-pyrrolidin-1-yl)-ethyl]-naphthalen-2-yl}-2H-pyridazin-3-one (5).

Provenance & Evidence