A Versatile One-Pot Synthesis of Fused Polycyclic Imidazole-naphthoquinone Derivatives through Imidazole-4,5-quinodimethane Generation Followed by Diels-Alder Cycloaddition
An efficient procedure for the trapping of an imidazole-4,5-quinodimethane intermediate 3 with quinones in boiling toluene and in the presence of 18-crown-6 is described. In all cases the fully aromatized imidazole-naphthoquinone derivatives were isolated as the main reaction products in satisfactory yields. However, in the case of benzo- and naphthoquinone, aromatized products were also isolated,
The first application of an imidazole o-quinodimethane in Diels–Alder reactions leading to the synthesis of benzimidazoles
作者:Constantinos Neochoritis、Despina Livadiotou、Julia Stephanidou-Stephanatou、Constantinos A. Tsoleridis
DOI:10.1016/j.tetlet.2007.01.162
日期:2007.3
An efficient procedure for the generation of the imidazole-4,5-quinodimethane intermediate 4 from 2-bromo-4,5-bis(bromomethyl)imidazole derivative 3 in boiling toluene in the presence of 18-crown-6 is described. o-Quinodimethane 4 was captured for the first time by several symmetrically and unsymmetrically substituted dienophiles to afford the corresponding Diels-Alder benzimidazole adducts. (c) 2007 Elsevier Ltd. All rights reserved.