Hydrochloric Acid → 3-{2-Ethyl-6-methyl-4-[3-oxo-3-(3,5,5-trimethyl-4,5,6,7-tetrahydro-benzo[c]thiophen-1-yl)-propenyl]-phenyl}-acrylic acid

Participants

Reaction Steps

A solution of 1-(3,5,5-trimethyl-4,5,6,7-tetrahydro-benzo[c]thiophen-1-yl)-ethanone (355 mg, 1.55 mmol) and 3-(2-ethyl-4-formyl-6-methyl-phenyl)-acrylic acid (373 mg, 1.70 mmol, Aldehyde 5) in methanolic NaOH (8 mL, 10 g NaOH in 100 mL methanol) is stirred at rt for 3 h before it is carefully acidified to pH 1 by adding 2 N aq. HCl. The mixture is extracted twice with DCM, the organic extracts are washed with water and brine, dried over MgSO4, filtered and evaporated. The crude product is crystallised from acetonitrile (120 mL) to give 3-{2-ethyl-6-methyl-4-[3-oxo-3-(3,5,5-trimethyl-4,5,6,7-tetrahydro-benzo[c]thiophen-1-yl)-propenyl]-phenyl}-acrylic acid (400 mg) as yellow crystals; LC-MS: tR=1.17 min, [M+1]=423.34; 1H NMR (CDCl3): δ 7.97 (d, J=16.4 Hz, 1H), 7.68 (d, J=15.2 Hz, 1H), 7.33 (s, 2H), 7.28 (d, J=15.8 Hz, 1H), 6.13 (d, J=15.8 Hz, 1H), 3.16 (t, J=7.0 Hz, 2H), 2.77 (q, J=7.6 Hz, 2H), 2.41 (s, 3H), 2.39 (s, 3H), 2.32 (s, 2H), 1.57 (t, J=6.4 Hz, 2H), 1.24 (t, J=7.6 Hz, 3H), 1.00 (s, 6H).

Provenance & Evidence