tert-butyl 2,2,2-trifluoroacetate

Conditions: temp:-60.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Dry tetrahydrofuran (84.6 ml) was added to diisopropylamine (dried with potassium hydroxide, 9.85 g, 0.0973 mole) nder a nitrogen atmosphere. The solution was cooled to -60° C. and thereto was added a 15% solution of n-butyllithium in n-hexane (58.5 ml, 0.0901 mole). After being stirred at 0° C. for 30 minutes, it was cooled to -75° C. A mixture of t-butyl trifluoroacetate (10.80 g, 0.0635 mole), 5-dimethylamino-3-methyl-1,2,4-oxadiazole (5.72 g, 0.0423 mole) and dry tetrahydrofuran (423 ml) was added dropwise to it at -73--75° C. over 1.5 hours. After being stirred at -75° C. for 1 hour, it was allowed to warm to room temperature over 1 hour. It was further heated to 50° C. and stirred for 30 minutes. 1N hydrochloric acid (190 ml) was then added thereto with ice cooling and tetrahydrofuran and n-hexane were distilled off under reudced pressure in a water bath at 40° C. After being extracted with methylene chloride, the extract was concentrated and purified column chromatrography on silica gel to give the crude title compound (8.91 g, crude yield 94.4%). Repeated recrystallizations from benzene gave colorless fine needles, m.p. 126.0°-126.5° C. The structure of this compound was confirmed by IR, NMR and elemental analysis. it was cooled to -75° C was added dropwise to it at -73--75° C. over 1.5 hours After being stirred at -75° C. for 1 hour to warm to room temperature over 1 hour It was further heated to 50° C. stirred for 30 minutes with ice cooling and tetrahydrofuran and n-hexane were distilled off under reudced pressure in a water bath at 40° C After being extracted with methylene chloride the extract was concentrated purified column chromatrography on silica gel

Conditions: temp:-75.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Under a nitrogen atmosphere, dry tetrahydrofuran (90 ml) was added to diisopropylamine (14.5 ml, 0.105 mole, 5.23 mole) and then to the solution was added a 15% solution of butyllithium in n-hexane (64 ml, 0.100 mole, 5.0 eq.) with cooling below 0° C. After keeping the mixture at 0° C. for 30 minutes, it was cooled at -75° C. The mixture of t-butyl trifluoroacetate (10.21 g, 0.0600 mole, 3 eq.), phenylacetamide oxime (3.00 g, 0.0200 mole) and dry tetrahydrofuran (45 ml) was added dropwise, keeping the mixture below -72° C. After the mixture was stirred at -75° C. for 1 hour, it was allowed to warm to room temperature over 1 hour. To the mixture was added 10% hydrochloric acid (90 ml, 0.246 mole) and refluxed for 2.5 hours. The reaction mixure was distilled under reduced pressure to remove tetrahydrofuran and n-hexane. The resulting residue was adjusted above pH 13 with a 48% solution of sodium hydroxide and extracted with methylene chloride. After the extract was dried with anhydrous sodium sulfate, the solvent was distilled off. The resulting residue was purified by column chromatography on alumina and silica gel to give the title compound (0.60 g, 13.1%). This product was recrystallized from cyclohexane to give colorless needles, m.p. 92.0°-93.0° C. The structure of this compound was confirmed by IR, NMR and UV. with cooling below 0° C at 0° C. for 30 minutes was added dropwise the mixture below -72° C to warm to room temperature over 1 hour refluxed for 2.5 hours The reaction mixure was distilled under reduced pressure to remove tetrahydrofuran and n-hexane extracted with methylene chloride After the extract was dried with anhydrous sodium sulfate the solvent was distilled off The resulting residue was purified by column chromatography on alumina and silica gel