Lithium diisopropylamide → 2-[(E)-2-(2,6-dichloro-3-methoxyphenyl)ethenyl]-5-methoxy-1H-indole

Participants

Reaction Steps

The 5-methoxy-1H-indole-2-carbaldehyde (1) was reacted with (2,6-dichloro-3-methoxybenzyl)(triphenyl)phosphonium bromide (526), prepared as described in example 117, using the procedure described in example 37, except that the aldehyde was added at 0° C., the ratio of LDA:aldehyde was 1.55:1 and the reaction time was 5 h, to give (after crystallisation from CH2Cl2/hexane) the diene (527) as a cream solid (the pure E isomer) (76%), mp 138–140° C. 1H NMR (CDCl3) δ 8.21 (br s, 1H), 7.32 (d, J=8.9 Hz, 1H), 7.26 (d, J=8.7 Hz, 1H), 7.22 (d, J=16.8 Hz, 1H), 7.04 (d, J=2.4 Hz, 1H), 6.92 (d, J=16.8 Hz, 1H), 6.87 (dd, J=8.8, 2.5 Hz, 1H), 6.80 (d, J=8.9 Hz, 1H), 6.61 (d, J=1.7 Hz, 1H), 3.92 (s, 3H), 3.85 (s, 3H). Found: C, 61.92; H, 4.52; N, 3.91. C18H15Cl2NO2 requires C, 62.09; H, 4.34; N, 4.02.

Provenance & Evidence