Abstract Oxidation of 3-furfurylamines 3a-e with bromine in acetone-water solution gave N- substituted 3-formylpyrroles 4a-e in good yields. A reaction mechanism via the Clauson- Kaas reaction followed by the cis-trans isomerization of the 2-ene-1, 4-diones 13 and 14 was proposed to account for the formation of the pyrroles 4a-e.
