ChemInform Abstract: 1,3‐ANIONIC CYCLOADDITIONS. XVII. SYNTHESIS OF IMIDAZOLINES AND IMIDAZOLES BY Y CYCLOADDITION OF 2‐AZAALLYLLITHIUM COMPOUNDS TO AROMATIC NITRILES

Abstract

Die Azaa1lyl‐Li‐Verbindung (Ia) reagiert mit den aromatischen Nitrilen (IIa), (IIb) , (IIe) zu den lithiierten Imidazolen (III), die durch nachfolgende Hydrolyse die freien Imidazole (IV) geben.

2-Azaallyl Anions, 2-Azaallyl Cations, 2-Azaallyl Radicals, and Azomethine Ylides

“…The reaction between semistabilized 2-azaallyl anions and aromatic nitriles proved to be more complex than other πelectrophiles; the outcome of the reactions, after aqueous workup, were highly dependent on the nature of the 2-azaallyl anion and the aryl nitrile (Scheme 18). 77,78 For example, 1,1diphenyl-2-azaallyllithium (6b) performed direct nucleophilic addition and double-bond isomerization, instead of cycloaddition, with either benzonitrile or picolinonitrile to afford enamines 55a and 55b, respectively, in moderate to poor yield. The same 2-azaallyl anion (6b) did undergo formal [3 + 2] cycloaddition, however, with more electron-rich aromatic nitriles to afford the corresponding 2,5-dihydro-1H-imidazoles 56a−56c in moderate yields.…”