Copper‐Mediated Oxidative [3+2]‐Annulation of Nitroalkenes and Ylides of 1,2‐Diazines: Assembly of Functionalized Pyrrolo[1,2‐b]pyridazines

Abstract

Oxidative [3 + 2]-annulation reactions between nitroalkenes and pyridazinium ylides mediated by Cu(OAc) 2 ⋅H 2 O were investigated. Functionalized pyrrolo[1,2-b]pyridazines and pyrrolo[1,2-a]phthalazines were accessed via this route. Starting from α-fluoronitroalkenes the reaction provides the first preparative synthesis of a broad scope of 5-fluoro-pyrrolo[1,2-b]pyridazines. The substrate scope in the case of α-unsubstituted nitroalkenes was investigated. Mechanistic features of the oxidative annulation reaction were studied to support the stepwise [3 + 2]-cycloaddition/oxidation/HNO 2 elimination mechanism. Partially saturated primary [3 + 2]-adducts were isolated and characterized as key intermediates.

Synthesis, Characterization and Cytotoxic Evaluation of New Pyrrolo[1,2-b]pyridazines Obtained via Mesoionic Oxazolo-Pyridazinones

“…The chemistry and applications of pyrrolo [1,2-b]pyridazines have been reviewed extensively in 1977 [9] and then in 2008 [11]. Subsequently, new developments in the synthetic aspects [12][13][14][15] and applications of pyrrolo [1,2-b]pyridazines regarding their pharmacological potentials such as antitumor [16][17][18], antibacterial [19], anti-inflammatory [20][21][22], antidepressant [23], antimetabolic [24] actions and their optical properties were reported [25,26].…”