Electrochemical reduction of substituted pyridazines: a new access to activated pyrroles

Synthesis of Polyhydroxylated Pyrano‐Pyrrole Derivatives from Carbohydrate Precursors

“…As a result of our interest in the synthesis of pyrrole heterocycles by ring contraction of pyridazine precursors using Boger's chemical strategy [16] or an alternative electrosynthesis methodology developed in our laboratory, [17][18][19][20] we have developed a synthesis of novel linear (pyrone type A) and cyclic polyhydroxylated pyrrolo-pyrone derivatives (pyrone types B and C) ( Figure 3) structurally analogous to boronolide (3a), altholactone (4), indololactone (10), or bergenin (11). Recently, we validated a general efficient synthetic approach to pyrrolo-pyrones A bearing a polyol side-chain.…”

Unravelling the Reaction Mechanism of the Reductive Ring Contraction of 1,2-Pyridazines

“…Generation of intermediates 19/23, however, is also very exergonic, and it is therefore very likely that the final protonation occurs on any of these intermediates, leading to the production of a mixture of intermediates 24-27 ( Table 1 Since NH 2 is not a good leaving group, the transfer of a proton to this group is now required. This 14 Finally, the 1,4-dihydropyridazine intermediate (4/6 in our scheme) found in electrochemical investigations 13,14 and isolated in the course of the total synthesis of ent-(-) roseophilin 9 seems to be part of an unproductive pathway involving (at the four-electron-reduced stage)…”

Synthesis and Electrochemical Behavior of Some New Pyridazine Derivatives

“…While, the reverse scan show three different reduction peaks at -495, -1438 and -2136 mV (vs. SCE). Voltammetric investigation performed at a sweep rate of 0.25 V s -1 indicates reversible systems [9]. Clear differences appear for the carbohydrazide derivative 7 (Fig.…”

“…N',N'-diacetyl-5-cyano-4-methyl-6-oxo-1-phenyl-1,6-dihydro-pyridazine-3-carbohydrazide (9) A mixture of compound 7 (0.005 mol) and acetic anhydride (5 ml) was heated under reflux for 1h. The acetic anhydride excess was evaporated under reduced pressure and the solid product obtained was recrystallized from ethanol to give 9.…”