期刊
TETRAHEDRON
卷 64, 期 26, 页码 6060-6072出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.tet.2008.01.051
关键词
imidazoles; direct arylation; regioselectivity; C-H bond activation; biologically active compounds
Highly selective, practical, and efficient protocols for the preparation of 4(5)-aryl-1H-imidazoles 2, 2,4(5)-diaryl-1H-imidazoles 3, and 4,5-diaryl-1H-imidazoles 1 are described. A key step of these protocols is the regioselective synthesis of 5-aryl-1-benzyl-1H-imidazoles 9 by Pd-catalyzed direct C-5 arylation of commercially available 1-benzyl-1H-imidazole (8) with aryl halides. The three- step synthesis of compounds 3 from 8 also involves the Pd-catalyzed and Cu-mediated direct C-2 arylation of imidazoles 9 with aryl halides under base-free and ligandless conditions. On the other hand, the four-step synthesis of imidazoles 1 from 8 also involves the regioselective bromination of compounds 9 and a Suzuki reaction of the resulting 5-aryl-1-benzyl-4-bromo-1H-imidazoles 11 with arylboronic acids 5 under phase-transfer conditions, followed by N-debenzylation. (C) 2008 Elsevier Ltd. All rights reserved.
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