Lithium diisopropylamide → 2-[(E)-2-(5-methoxy-1H-indol-2-yl)ethenyl]benzonitrile

Participants

Reaction Steps

The 5-methoxy-1H-indole-2-carbaldehyde (1) was reacted with (2-cyanobenzyl)(triphenyl)phosphonium bromide (547) prepared as described in example 136 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 1.55:1 and the reaction time was 5 h, to give (after crystallisation from CH2Cl2/hexane) the diene (548) as a yellow solid (the pure E isomer) (60%), mp 192–196° C. 1H NMR (CDCl3) δ 8.40 (br s, 1H), 7.79 (d, J=8.1 Hz, 1H), 7.66 (dd, J=8.1, 0.9 Hz, 1H), 7.58 (td, J=7.9, 1.3 Hz, 1H), 7.32 (td, J=8.0, 0.9 Hz, 1H), 7.29 (d, J=8.5 Hz, 1H), 7.28 (d, J=16.9 Hz, 1H), 7.18 (d, J=16.4 Hz, 1H), 7.04 (d, J=2.4 Hz, 1H), 6.91 (dd, J=8.9, 2.4 Hz, 1H), 6.64 (d, J=1.8 Hz, 1H), 3.86 (s, 3H). Found: C, 79.05; H, 5.16; N, 10.31. C18H14N2O requires C, 78.81; H, 5.14; N, 10.21.

Provenance & Evidence