Ammonium Chloride → 1-(2-Ethoxyphenyl)-4-[2-(6-aminocarbonylisochroman-1-yl)ethyl]piperazine

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Reaction Steps

A dry 25 ml round bottom flask is charged with THF (2 ml) and cooled to -78°. t-butyllithium in hexanes (1.6 M, 1.18 ml, 2 mmol) is added at once via syringe and stirred for 5 min. A solution of 1-(2-ethoxyphenyl)-4-[2-(6-bromoisochroman-1-yl)-ethyl]piperazine (CXXVI, EXAMPLE 126) in THF (3 ml) is added via canula, and stirred for another 10 min. Dry carbon dioxide gas is bubbled through the reaction mixture for 10 min, while maintaining the dry ice/acetone cooling bath. The reaction mixture is warmed to 20-25°. When the gas evolution stopped, oxalyl chloride (0.13 ml, 1.5 mmol) is added dropwise via syringe, followed by DMF (4 drops). After two hours of stirring, the reaction mixture is poured into ammonium chloride (40 ml), extracted two times with equal volumes of methylene chloride (which are combined), dried with sodium sulfate, filtered and concentrated. The concentrate is purified by flash chromatography (silica gel, 25 g; eluting with methanol/ethyl acetate (10/90) to give the impure product. The impurity is removed by triturating with methylene chloride and hexane to leave an oil which is converted into the hydrochloride salt using ethereal hydrochloric acid to give the title compound, mp 208-210°; HRMS Calcd for C24H31N3O3 =409.2365, found=409.2364.

Provenance & Evidence