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

Participants

Reaction Steps

The 5-methoxy-1H-indole-2-carbaldehyde (1) was reacted with (3-nitrobenzyl)(triphenyl)phosphonium bromide 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 MeOH/CH2Cl2/hexane) the diene (551) as an orange-red solid (the pure E isomer) (51%), mp 178–182° C. 1H NMR [(CD3)2SO] δ 11.27 (br s, 1H), 8.34 (t, J=1.9 Hz, 1H), 8.09 (dd, J=8.1, 1.8 Hz, 1H), 7.99 (d, J=7.9 Hz, 1H), 7.67 (t, J=8.0 Hz, 1H), 7.47 (d, J=16.5 Hz, 1H), 7.26 (d, J=8.6 Hz, 1H), 7.25 (d, J=16.6 Hz, 1H), 7.03 (d, J=2.4 Hz, 1H), 6.77 (dd, J=8.8, 2.5 Hz, 1H), 6.61 (d, J=1.6 Hz, 1H), 3.76 (s, 3H). Found: C, 69.36; H, 4.77; N, 9.78. C17H14N2O3 requires C, 69.38; H, 4.79; N, 9.52.

Provenance & Evidence