Hydrochloric Acid → ethyl 7-(1,1-Dimethylethyl)-2-(pentafluoroethyl)-2H-1-benzopyran-3-carboxylate

Participants

Reaction Steps

A mixture of 4-tert-butylsalicylaldehyde Example 8, step 1 (1.15 g, 6.4 mm) and the ethyl ester from Step 2 (1.59 g, 7.3 mmol) was dissolved in anhydrous DMF (4 mL). With stirring, K2CO3 (1.10 g, 9.0 mmol) was added causing the reaction to become deep red. The reaction was stirred at room temperature for 100 hours, acidified with 3 N HCl, diluted with ethyl acetate and washed with saturated NaHCO3 solution, brine, dried over MgSO4, filtered and concentrated in vacuo yielding a brown oil. This oil was purified by flash chromatography over silica gel, eluting with 10% ethyl acetate/hexanes to afford a yellow oil (1.72 g, 70%): 1H NMR (CDCl3/300 MHz) 7.76 (s, 1H), 7.14 (d, 1H, J=8.1 Hz), 7.04 (dd, 1H, J=8.1 Hz 1.8 Hz), 6.94 (s, 1H), 5.92 (dd, 1H, J=22.4 Hz 3.0 Hz), 4.32 (m, 2H), 1.35 (t, 3H, J=7.2 Hz), 1.30 (s, 9H).

Provenance & Evidence