Synthesis of Di- and Tri-Substituted Imidazole-4-carboxylates via PBu<sub>3</sub>-Mediated [3 + 2] Cycloaddition
                                
                                    
                                        作者:Mei-Yuan Hsu、Justin Dietrich、Christopher Hulme、Arthur Y. Shaw                                    
                                    
                                        DOI:10.1080/00397911.2011.644846
                                    
                                    
                                        日期:2013.6.3
                                    
                                    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.