The First Examples of Nazarov Cyclizations Leading to Annulated Pyrroles
摘要:
Reactions between alpha-substituted unsaturated carboxylic acids 20 and N-tosylpyrroles [14, 23] in the presence of trifluoroacetic anhydride result in smooth alpha-acylation of the pyrrole, followed by Nazarov cyclization to give 50-80% yields of cyclopenta[b]pyrroles. The presence of an alpha-substituent in the unsaturated acid appears to be mandatory.