Acetic Anhydride → 2-Acetyl-3-hydroxy-5-(3-(6-methoxypyridin-2-yl)thiophen-2-yl)cyclohex-2-enone

Participants

Reaction Steps

To a 200 mL recovery flask was added 3-hydroxy-5-(3-(6-methoxypyridin-2-yl)thiophen-2-yl)cyclohex-2-enone (30F, 4.9 g, 16.3 mmol, 1.0 eq.), CH2Cl2 (100 mL), acetic anhydride (2.15 g, 21.1 mmol, 1.3 eq.), Et3N (6.8 mL, 48.8 mmol, 3.0 eq.), and DMAP (catalytic). The reaction mixture was stirred overnight at room temperature whereupon LC/MS showed two signals corresponding to M+H=344. Additional acetic anhydride (0.5 mL, 5.3 mmol, 0.32 eq.) was added and the reaction mixture was heated for 6 h at 40° C. LC/MS analysis showed the reaction to be complete whereupon the mixture was concentrated to a solid and purified via flash chromatography (70% CH2Cl2/Hex to 100% CH2Cl2) to yield a dark orange solid 30G (1.72 g, 31%). 1H NMR (400 MHz, DMSO-d6) δ ppm 2.52-2.57 (m, 3H) 2.83 (m, 2H) 3.09 (m, 2H) 3.78 (s, 3H) 4.68 (m, 1H) 6.74 (d, J=8.34 Hz, 1H) 7.32 (d, J=7.33 Hz, 1H) 7.41-7.47 (m, 1H) 7.51 (d, J=5.31 Hz, 1H) 7.76 (t, J=7.96 Hz, 1H). ESI-MS: m/z 344.3 (M+H)+.

Provenance & Evidence