Efficient, Regioselective Access to Bicyclic Imidazo[1,2-<i>x</i>]- Heterocycles via Gold- and Base-Promoted Cyclization of 1-Alkynylimidazoles
作者:Christophe Laroche、Sean M. Kerwin
DOI:10.1021/jo902073m
日期:2009.12.4
derivatives followed by addition of aldehydes or ketones are presented. The method gives access to 1-alkynyl-2-(hydroxymethyl)imidazoles which undergo 6-endo-dig or 5-exo-dig cyclization under AuCl3- or base-catalyzed conditions to yield imidazo[1,2-c]oxazoles and imidazo[2,1-c][1,4]oxazine heterocycles. Under transition metal catalysis, the reaction occurs in a regiospecific manner, leading exclusively
提出了1-炔基咪唑的反应,包括它们的2-硫代衍生物的形成,然后加入醛或酮。该方法提供了在AuCl 3-或碱催化的条件下进行6-内-挖或5- exo-挖环化反应的1-炔基-2-(羟甲基)咪唑,生成咪唑并[1,2- c ]恶唑和咪唑并[2,1- c ] [1,4]恶嗪杂环。在过渡金属催化下,该反应以区域特异性方式发生,仅导致6 -endo-dig攻击的产物,而在碱性条件下,该反应以区域选择性方式发生,优先提供5 -exo-dig攻击的产物。。
Coupling Reactions of Bromoalkynes with Imidazoles Mediated by Copper Salts: Synthesis of Novel <i>N</i>-Alkynylimidazoles
作者:Christophe Laroche、Jing Li、Matthew W. Freyer、Sean M. Kerwin
DOI:10.1021/jo801118q
日期:2008.8.1
A cross-coupling reaction of imidazoles with bromoalkynes in the presence of a catalytic amount of CuI is reported. This protocol allows an access to novel N-(1-alkynyl)imidazoles in moderate to good yields.
Cu-Catalyzed N<i>-</i>Alkynylation of Imidazoles, Benzimidazoles, Indazoles, and Pyrazoles Using PEG as Solvent Medium
作者:Glenn A. Burley、David L. Davies、Gerry A. Griffith、Michael Lee、Kuldip Singh
DOI:10.1021/jo902466f
日期:2010.2.5
A facile and efficient Cu(I)-catalyzed cross-coupling method is reported for the preparation of N-alkynyl or N-bromoalkenyl heteroarenes from bromoalkynes. Generally superior yields and functional group tolerance were obtained with microwave (MW) irradiation using imidazole, benzimidazole, pyrazole, and indazole substrates and poly(ethylene glycol) 400 (PEG400) as an additive. We speculate that PEG400 acts as both a Cu(I)-stabilizing ligand as well as a phase transfer solvent.