Summary.
Pyrrole α-aldehydes (2-formyl-4,5-dimethyl-1H-pyrrole and 2-formyl-N-methylpyrrole) condense readily at C(3) of indolin-2-ones to give dipyrrinone analogs, such as (3Z)-[(4,5-dimethylpyrrol-2-yl)-methylidenyl]-indolin-2-one and (3E)-[(1-methylpyrrol-2-yl)-methylidenyl]-indolin-2-one. 1H-NMR NOE analyses and X-ray crystallography confirm the syn-(Z) configuration for the former and the syn-(E) configuration for the latter. The former is stabilized by intramolecular hydrogen bonding. Molecular mechanics calculations of the latter indicate no energy difference between the syn and anti conformations.
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Corresponding author. E-mail: lightner@scs.unr.edu
Received August 2, 2002; accepted August 30, 2002
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Boiadjiev, S., Lightner, D. Conformation and Crystal Structure of Dipyrrinones with Oxindole Components. Monatshefte für Chemie 134, 489–499 (2003). https://doi.org/10.1007/s00706-002-0542-3
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DOI: https://doi.org/10.1007/s00706-002-0542-3