| Popis: |
The electrochemical two electron reduction of pyridazines, substituted by electron withdrawing groups, primarily lead to their corresponding 1,2-dihydro-derivatives. Depending on the nature of the ring substitution, these intermediates can either rearrange into 1,4-dihydro-pyridazines, or undergo electrochemical reduction to give rise to activated pyrroles by a ring contraction reaction with extrusion of nitrogen. Another way of access to the latter has been achieved by a disproportionation reaction of 1,2-dihydro-pyridazines, leading directly to the expected pyrroles and recovery of 50% of pyridazines. |
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