Trifluoroacetic anhydride → Kabi 2023

Participants

Reaction Conditions

Reaction Steps

N-Methyl-2-[spiro(cyclopentane-1,1'-indene)-3'-yliden]ethylamine (8.1 g; Swedish Pat. No. 7203905-0) in diethyl ether (100 ml) is treated with trifluoroacetic anhydride (8 ml) while being stirred with powdered anhydrous sodium carbonate (6 g). The solid is filtered off and the solvent is evaporated from the filtrate. The crude N-trifluoroacetyl-N-methylspiro(cyclopentane-1,1'-indan)-3'-ylideneethylamine is dissolved in dichloromethane (100 ml), added to sodium bicarbonate solution (40 ml; 0.5 M) and treated in portions with m-chloroperbenzoic acid (50%; 3.4 g) with stirring at about 20° C. After stirring for 2 hours, the solution is washed with saturated sodium carbonate solution and water, and dried with sodium sulphate. After filtration, the solvent is evaporated. The crude epoxy compound is dissolved in tetrahydrofuran (100 ml), and treated with perchloric acid (10 drops) at room temperature for 2 hours. After evaporation of the solvent the remaining crude 2-(N-methyltrifluoroacetamido)-1-[spiro(cyclopentane-1,1'-indene)-3'-yl]-ethanol is dissolved in a mixture of methanol (20 ml), water (50 ml) and potassium carbonate (10 g) and stirred overnight. The methanol is evaporated under reduced pressure and the free amine is extracted into dichloromethane. After drying with sodium sulphate the solvent is evaporated. The title compound is crystallized from diisopropyl ether; m.p. 134° C.

Provenance & Evidence