Paal-Knorr pyrrole synthesis

Hemiaminal intermediate

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Sn2

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This shows the mechanism for pyrrole synthesis based on recent DFT study. Instead of the formation and cyclisation of a enamine intermediate, a hemiaminal intermediate in formed, followed by the consecutive dehydrations of the two hydroxyl groups. The dehydration steps may look familiar: it is just the formation of an enamine

A more traditional approach to the mechanism, which appears in some text books and taught courses, can be found here.

This mechanism was based on the paper: B. Mothana, R. J. Boyd, J. Mol. Struct.: THEOCHEM, 2007, 811, 97-107

 

 

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