Synthesis of N-alkoxybenzimidazoles and N-alkoxypyrimidazoles.

A variety of novel N-alkoxy aromatic-fused imidazoles have been prepared in a simple two-step process from 2-fluoro nitroaromatics and 2-chloro-3-nitropyridine. The imidazole forming step involves tandem heterocyclisation and O-alkylation with an in situ alkylating agent, and supports prior mechanistic proposals. Additional mechanistic experiments are described. The protocol is versatile with respect to both substrate halo-nitro aromatics and to the nature of the added electrophile (halides) used in the second step, and thereby significantly extends the scope of this reaction and its applicability to diverse synthesis. This methodology can also be used to generate various types of novel N-alkoxypyrimidazoles (4-deazapurine analogues), and an X-ray structure of one such pyrimidazole is presented. (C) 2002 Elsevier Science Ltd. All rights reserved.