REACTION OF THE FISCHER BASE WITH NITRO- AND BROMO-SUBSTITUTED o-HYDROXYCINNAMALDEHYDES

Article abstract of DOI:10.1007/BF00508670

The Fischer base reacts with α-ethyl-5-nitro-, 5-bromo-, and 3,5-dibromo-2-hydroxycinnamaldehydes to give bisindole spirochromans, with 3-bromo-5-nitro-2-hydroxycinnamaldehyde to give a mixture of a spirochroman and monoindole merocyanine, and with 3,5-dinitro-2-hydroxycinnamaldehyde to give only a merocyanine.The monoindole merocyanines obtained do not display a tendency to undergo intramolecular cyclization to give spiro-2H-oxocines.