Acetone → (E)-4-(3-(6-methoxypyridin-2-yl)thiophen-2-yl)but-3-en-2-one

Participants

Reaction Conditions

Reaction Steps

To a 500 mL recovery flask was added 3-(6-methoxypyridin-2-yl)thiophene-2-carbaldehyde (30C, 6.2 g, 28.3 mmol, 1.0 eq.), acetone (16.6 mL, 226 mmol, 8.0 eq.), and H2O (130 mL). Upon cooling to 0° C. in an ice bath, aqueous NaOH (5N, 6.2 mL, 31.1 mmol, 1.1 eq.) was added. The reaction mixture was stirred overnight while warming to room temperature. LC/MS monitoring showed the reaction to be ˜60% complete, so additional aqueous NaOH (5N, 1 mL, 5.0 mmol, 0.18 eq.) was added. After stirring for an additional 6 h the reaction was complete by LC/MS. The reaction mixture was neutralized with 3N aqueous HCl to a pH ˜8. The mixture was extracted with EtOAc (3×100 mL). The organic phases were combined and washed with saturated aqueous NaCl (100 mL). The combined aqueous phases were extracted with EtOAc (100 mL). The organic phases were combined and dried over anhydrous Na2SO4, filtered, and concentrated to give a black solid. The residue was purified via flash chromatography (60% CH2Cl2/Hex to 100% CH2Cl2) to give a yellow solid 30D (4.8 g, 67%). 1H NMR (400 MHz, DMSO-d6) δ ppm 2.29 (s, 3H) 3.96 (s, 3H) 6.59 (d, J=15.92 Hz, 1H) 6.84 (d, J=8.34 Hz, 1H) 7.41 (d, J=7.58 Hz, 1H) 7.60 (d, J=5.31 Hz, 1H) 7.75-7.88 (m, 2H) 8.71 (d, J=15.92 Hz, 1H). ESI-MS: m/z 260.3 (M+H)+.

Provenance & Evidence