5-Methoxy-1H-indole-2-carbaldehyde → Benzyl (2E)-3-(5-methoxy-1H-indol-2-yl)-2-propenoate

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Reaktionsschritte

Benzyl (triphenylphosphoranylidene)acetate (49.2 g, 0.120 mol) was added to a stirred solution of 5-methoxy-1H-indole-2-carbaldehyde (1) (20.0 g, 0.114 mol) in CH2Cl2 (500 mL) and the solution was stirred at room temperature for 4 h. The solvent was removed in vacuo and the residue slurried with methanol (200 mL), whereupon crystallisation of the product occurred. The mixture was filtered, washed with several portions of cold methanol, and dried to give benzyl (2E)-3-(5-methoxy-1H-indol-2-yl)-2-propenoate (2) in a 30.46 g, 87% yield as pale yellow plates; mp 155–157° C. 1H NMR δ (CDCl3) 8.28 (s, 1H), 7.69 (d, J=16.1 Hz, 1H), 7.43–7.32 (m, 5H), 7.23 (d, J=9.1 Hz, 1H), 7.03 (d, J=2.3 Hz, 1H), 6.92 (dd, J=9.1, 2.3 Hz, 1H), 6.74 (d, J=1.8 Hz, 1H), 6.24 (d, J=16.1 Hz, 1H), 5.26 (s, 2H), 3.84 (s, 3H).Found: C, 74.45; H, 5.62; N, 4.58. C19H17NO3 requires C, 74.25; H, 5.57; N, 4.56.

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