2-Methyltetrahydrofuran → 4-(7-Azabicyclo[2.2.1]heptan-7-yl)-2-(trifluoromethyl)aniline

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Reaction Steps

Preparation 4-(7-azabicyclo[2.2.1]heptan-7-yl)-2 -(trifluoromethyl)aniline hydrochloride (11B), method 1. Palladium on carbon (150 g, 5% w/w) was charged into a Büchi Hydrogenator (20 L capacity) under a nitrogen atmosphere, followed by the addition of 7-[4-nitro-3-(trifluoromethyl)phenyl]-7-azabicyclo[2.2.1]heptane (10A, 1500 g), as prepared in Example 2A (method 2) above, and 2-methyltetrahydrofuran (10.5 L, 7 vol). The hydrogenator was then purged with Hydrogen gas and then continuously charged to the mixture at a pressure of 0.5 bar above atmospheric pressure. The mixture was then stirred at a temperature between 18° C. and 23° C. by cooling the vessel jacket. A vacuum was applied to the vessel when no more hydrogen gas was consumed and when there was no further exotherm. Nitrogen gas was then charged into the vessel at 0.5 bar and a vacuum was reapplied, followed by a second charge of 0.5 bar nitrogen gas. When the HPLC of a filtered aliquot showed that none of 7-[4-nitro-3-(trifluoromethyl)phenyl]-7-azabicyclo[2.2.1]heptane (10A) remained (e.g., ≦0.5%), the reaction mixture was transferred to a receiving flask under nitrogen atmosphere via a filter funnel using a Celite filter. The Celite filter cake was washed with 2-methyltetrahydrofuran (3 L, 2 vol). The washings and filtrate were charged into a vessel equipped with stirring, temperature control, and a nitrogen atmosphere. 4M HCl in 1,4-dioxane (1 vol) was added continuously over 1 h into the vessel at 20° C. The mixture was stirred for at least an additional 10 h, filtered, and washed with 2-methyltetrahydrofuran (2 vol) and dried to generate 1519 g of the hydrochloride salt of 4-(7-azabicyclo[2.2.1]heptan-7-yl)-2-(trifluoromethyl)aniline (11B) as a white crystalline solid.

Provenance & Evidence