Lithium diisopropylamide → 2-[(E)-2-(2-chloro-3-nitrophenyl)ethenyl]-5-methoxy-1H-indole

Participants

Reaction Steps

The 5-methoxy-1H-indole-2-carbaldehyde (1) was reacted with (2-chloro-3-nitrobenzyl)(triphenyl)phosphonium bromide (554) preared as described in example 143 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/pentane) the diene (555) as an orange crystalline solid (the pure E isomer) (50%), mp 131–133° C. 1H NMR (CDCl3) δ 8.24 (br s, 1H), 7.86 (dd, J=8.0, 1.4 Hz, 1H), 7.63 (dd, J=7.9, 1.4 Hz, 1H), 7.40 (t, J=8.0 Hz, 1H), 7.28 (d, J=8.5 Hz, 1H), 7.25 (d, J=15.8 Hz, 1H), 7.15 (d, J=16.4 Hz, 1H), 7.05 (d, J=2.4 Hz, 1H), 6.91 (dd, J=8.9, 2.4 Hz, 1H), 6.65 (d, J=1.7 Hz, 1H), 3.86 (s, 3H). Found: C, 61.97; H, 3.92; N, 8.50. C17H13ClN2O3 requires C, 62.11; H, 3.99; N, 8.52.

Provenance & Evidence