Synthesis of Di- and Tri-Substituted Imidazole-4-carboxylates via PBu3-Mediated [3 + 2] Cycloaddition
摘要:
Some new di- and trisubstituted imidazole-4-carboxylates were prepared from amidoacetic acids 3 in the present report. The key step to establish such imidazole-4-carboxylates stemmed from the PBu3-mediated [3+2] cycloaddition between in situ-generated 2-oxazolinone 4 and ethyl cyanoformate6. Our results indicated that trisubstituted imidazoles 7-20 were afforded in better yields than those of disubstituted imidazoles 21-27. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications (R) to view the free supplemental file.
An efficient method for the synthesis of polyfunctional imidazoles from vinyl azides and amidine has been developed. Starting from vinyl azide and amidine, this transformation proceeds without any additives and the obtained imidazoles can be decorated with ester functional group that is a promising site for further modification.