Synthesis of 2, 5, 6-Trisubstituted Benzimidazoles by Heck and Subsequent 6π-Electrocyclization-Dehydrogenation Reactions of 2, 4, 5-Tribromo-N-methylimidazole …
SMT Toguem, P Langer
文献索引:Toguem, Serge-Mitherand Tengho; Langer, Peter Synlett, 2010 , # 12 p. 1779 - 1782
Commercially available tribromoimidazole (1) was transformed into tribromo-N-methyl-imidazole (2) by reaction with potassium carbonate and methyl iodide in DMF (Scheme [¹] ). The Heck reaction of 2 with acrylates 3a-g (3.3 equiv) afforded the tri(alkenyl)-N-methyl-imidazoles 4a-g in 73-86% yield (Table [¹] ). [¹³] [¹4] The Heck reaction of 2 with styrene 3h gave product 4h. The best yields were obtained when Pd(OAc) 2 (5 mol%) in the presence of tris(cyclohexyl) ...
[Iddon, Brian; Lim, Bee Lan Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1983 , # 4 p. 735 - 739]