α-Diimine synthesis via titanium-mediated multicomponent diimination of alkynes with C-nitrosos

Abstract

α-Diimines are commonly used as supporting ligands for a variety of transition metal-catalyzed processes, most notably in α-olefin polymerization. They are also precursors to valuable synthetic targets, such as chiral...

Non‐Symmetrical Tetraaryl‐α‐Diimines via Transimination: A Promising Route for Non‐Symmetrical 1,3,4,5‐Tetraarylimidazolium Chlorides

“…The successful synthesis of these molecules enabled us to envision new non-symmetrical 1,3,4,5-tetraaryl imidazolium chlorides. [26][27][28][29] Our initial attempts to cyclize the synthesised non-symmetrical tetraaryl-α-diimines using paraformaldehyde was found to be unsuccessful [43][44][45] and resulted in the formation of corresponding anilinium salts. Therefore, the cyclization was pursued with methoxymethyl chloride [46] as the pre-carbenic unit and it was found to be highly efficient in preparing a series of new non-symmetrical 1,3,4,5-tetraaryl imidazolium chlorides successfully (Table 4).…”

“…The successful synthesis of these molecules enabled us to envision new non‐symmetrical 1,3,4,5‐tetraaryl imidazolium chlorides [26—29] . Our initial attempts to cyclize the synthesised non‐symmetrical tetraaryl‐α‐diimines using paraformaldehyde was found to be unsuccessful [43–45] and resulted in the formation of corresponding anilinium salts.…”

“…[1,26,27] But in general, the sequential condensation route, lacks broad scope and found to be inefficient for making non-symmetrical tetraaryl α-diimines. Recently, Ti-mediated oxidative diimination of alkynes was reported [28] for the synthesis of symmetrical and non-symmetrical α-diimines (Scheme 1C). This methodology utilises multistep synthesis.…”

Diaza-1,3-butadienes as Useful Intermediate in Heterocycles Synthesis

“…The 1,4-diaza-1,3-butadienes 4 or α-diimines, which have two imine groups, are synthesized primarily through the condensation reaction of 1,2-diketones, ketoaldehydes, or glyoxal with primary amines [ 19 ]. This technique yields symmetric diimines, and despite its simplicity, preparing unsymmetrical α-diimines is difficult; however, many methods for doing so have been reported [ 20 ]. On the other hand, because of the presence of nitrogen atoms in the structure of 1,4-diazadienes, they are known as ligands in coordination chemistry since the pioneering work of Dieck et al [ 21 ].…”

Copper Iodide-Mediated Synthesis of α-Diimine Ligands from Bis(imidoyl chlorides) and Arylstannanes

“…The third synthetic route for α-diimine preparation is cross-coupling between isonitriles and aryl halides or arylmetal reagents (Scheme , pathway C) . The method most relevant to the current study is homologation of bis­(imidoyl chlorides) (Scheme , pathway D) . In 1997, Faust and Göbelt introduced palladium-mediated double Stille coupling of organostannanes with bis­(imidoyl chlorides) to afford diimines. , This work is based on earlier reports in which (mono)­imidoyl chlorides were coupled with organometallic reagents − and remains the only example of the use of bis­(imidoyl)­chlorides in transition-metal-catalyzed coupling reactions to generate 1,2-diimines .…”