Lithium diisopropylamide → 2-[(E)-2-(2-chloro-4-nitrophenyl)ethenyl]-5-methoxy-1H-indole

Participants

Reaction Steps

The 5-methoxy-1H-indole-2-carbaldehyde (1) was reacted with (2-chloro-4-nitrobenzyl)(triphenyl)phosphonium bromide (559) prepared as described in example 148 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 1.5:1 and the reaction time was 5 h, to give (after crystallisation from CH2Cl2/hexane) the diene (560) as a dark red-brown solid (the pure E isomer) (46%), mp 239–241° C. 1H NMR [(CD3)2SO] δ11.57 (br s, 1H), 8.32 (d, J=2.0 Hz, 1H), 8.18 (dd, J=8.8, 2.1 Hz, 1H), 8.15 (d, J=8.9 Hz, 1H), 7.59 (d, J=16.3 Hz, 1H), 7.47 (d, J=16.3 Hz, 1H), 7.29 (d, J=8.9 Hz, 1H), 7.05 (d, J=2.4 Hz, 1H), 6.82 (dd, J=8.7, 2.5 Hz, 1H), 6.70 (s, 1H), 3.76 (s, 3H). Found: C, 62.14; H, 3.91; N, 8.52. C17H13ClN2O3 requires C, 62.11; H, 3.99; N, 8.52.

Provenance & Evidence