5-Methoxy-1H-indole-2-carbaldehyde → 2-[(E)-2-(2,6-dichlorophenyl)ethenyl]-5-methoxy-1H-indole

Participants

Reaction Steps

The 5-methoxy-1H-indole-2-carbaldehyde (O) was reacted with (2,6-dichlorobenzyl)(triphenyl)phosphonium bromide (511) prepared as described in example 102 using the procedure described in example 37, except that the LDA and aldehyde were (sequentially) added at 0° C., the ratio of LDA aldehyde was 1.37:1 and the reaction time was 5 h, to give (after crystallisation from CH2Cl2/hexane) the diene (512) as a yellow solid (the pure E isomer) (97%), mp 144–147° C. 1H NMR (CDCl3) δ 8.20 (br s, 1H), 7.36 (d, J=8.1 Hz, 1H), 7.27 (m, 1H), 7.25 (d, J=16.8 Hz, 1H), 7.11 (t, J=8.0 Hz, 1H), 7.03 (d, J=2.4 Hz, 1H), 6.93 (d, J=16.8 Hz, 1H), 6.88 (dd, J=8.7, 2.5 Hz, 1H), 6.61 (d, J=1.8 Hz, 1H), 3.86 (s, 3H). Found: C, 64.04; H, 4.13; N, 4.39. C17H13Cl2NO requires C, 64.17; H, 4.12; N, 4.40.

Provenance & Evidence