Trifluoroacetic anhydride → 3-t-Butyl-4-Isopropoxy-3-cyclobutene-1,2-dione

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Reaction Steps

t-Butyl lithium (2.29 ml of a 1.7M solution in pentane, 3.9 mmol) was added to a solution of 3,4-diisopropoxy-3-cyclobutene-1,2-dione (594 mg, 3 mmol) in THF (30 ml) at −78° C. After 5 h trifluoroacetic anhydride (636 μl, 4.5 mmol) was added and stirring continued at −78° C. for 30 min. The cold mixture was poured into NH4Cl(aq), extraced with EtOAc, dried (Na2SO4) and evaporated in vacuo. Column chromatography (SiO2; EtOAc/hexane, 15:85) gave the title compound as a mobile yellow oil (408 mg, 69%). δH (CDCl3) 5.43 (1H, sept, J 6.2 Hz), 1.45 (6H, d, J 6.2 Hz) and 1.33 (9H, s); m/z (ES+, 70V) 197 (MH+).

Provenance & Evidence