Hydrochloric Acid → 2,2,2-Trifluoro-N-phenylacetamide

Participants

Reaction Conditions

Reaction Steps

A solution of o-bromotrifluoroacetanilide (325 mg, 1.2 mM) in tetrahydrofuran (THF)(20 cm3) was cooled to -78° C. and to this was added methyl lithium (1 molar equivalent of a 1.4 M solution in diethyl ether). This addition was followed 10 minutes later by the introduction of tert-butyllithium (2 molar equivalent of a 1.7 M solution in pentane). The reaction mixture was stirred for 1 hour at -78° C., and then a solution of the chloroindanone (272 mg. 1.2 mM) in THF (3 cm3) added dropwise via a cannula. The solution was allowed to warm slowly to room temperature, and stirred for one hour, then a 10% solution potassium hydroxide in methanol (3 cm3) was introduced. After stirring for 30 minutes, the reaction mixture was poured into 2 M HCl, and extracted with dichloromethane (3 ×10 cm3). The combined organic extracts were dried (Na2SO4 ) and evaporated in vacuo to afford a solid residue which was chromatographed on silica, eluting with 10% ethyl acetate/petroleum ether (60°-80° C.) to yield trifluoroacetanilide (RF 0.4)(50 mg), and the 2-chloro-1-hydroxy-5-methoxy-4,6-dimethyl-1-(2'-trifluoroacetamidophenyl)indane (RF 0.3) (220 mg, 44%). The latter compound is a colourless solid. M.p. 182° C. 1H NMR (CDCl3)δ: 10.7 (1H, br), 8.25 (1H, dd), 7.36 (1H, ddd), 7.06 (1H, s), 6.98 (1H, ddd), 6.39 (1H, dd), 4.76 (1H, dd, J=4.8, 2.7Hz), 3.78 (3H, s), 3.63 (1H, s, exchanges with D2O), 3.11 (2H, 2 ×2nd order multiplets), 2.33 (3H, s), 2.23 (3H, s).

Provenance & Evidence