Methyl 5-formylthiophene-2-carboxylate → methyl (E)-5-[2-(3-hexyl-5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-vinyl]-thiophene-2-carboxylate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A suspension of 1.917 g of (3-hexyl-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-naphthalen-2-yl)-methyl triphenylphosphonium bromide (From Example 7.1) in 40 ml THF was cooled to −78° C. and treated with 1.91 ml of butyllithium 1.6 M in hexane. The mixture was allowed to warm to room temperature for 30 min. then was cooled back to −78° C. A solution of 495 mg of methyl 5-formylthiophene-2-carboxylate in 10 ml THF was added. The mixture was kept at −78° C. for 30 min. then was allowed to warm to room temperature for 30 min. The reaction mixture was diluted with 50 ml of a saturated ammonium chloride solution and extracted with 3 portions of 50 ml of ethyl acetate. The combined organic extracts were dried (MgSO4), filtered and concentrated in vacuo, giving a yellow solid. Flash chromatography (SiO2, 3% ethyl acetate/hexane) gave 1.2 g of a mixture (E/Z) of the desired product. Chromatography on a medium pressure liquid chromatography system (3% ethyl acetate/hexane) provided 1.12 g of the title product without trace of the Z isomer. 1H NMR (CDCl3): 7.69 (d, J=4.5 Hz, 1H), 7.48 (s, 1H), 7.30 (d, J=15.6 Hz, 1H), 7.09 (s, 1H), 7.05 (d, J=4.9 Hz, 1H), 7.04 (d, J=15.6 Hz, 1H), 3.89 (s, 3H), 2.67 (t, J=8.3 Hz, 2H), 1.68 (s, 4H), 1.2-1.5 (m, 8H), 1.32 (s, 6H), 1.28 (s, 6H), 0.90 (t, J=7.0 Hz, 3H).

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