Silver(I)-Catalyzed Cascade: Direct Access to Furans from Alkynyloxiranes
作者:Aurélien Blanc、Katharina Tenbrink、Jean-Marc Weibel、Patrick Pale
DOI:10.1021/jo900483m
日期:2009.6.5
Functionalized furans are conveniently formed by a new silver(I)-catalyzed reaction of alk-1-ynyl oxiranes in the presence of p-toluenesulfonic acid and methanol. Evidence supported a cascade mechanism.
Mechanistic Studies and Improvement of Coinage Metal-Catalyzed Transformation of Alkynyloxiranes to Furans: An Alcohol Addition−Cyclization−Elimination Cascade
作者:Aurélien Blanc、Katharina Tenbrink、Jean-Marc Weibel、Patrick Pale
DOI:10.1021/jo9008172
日期:2009.8.7
In the presence of alcohol Ag or Au salts or complexes catalyze the conversion of alkynyloxiranes to substituted furans. Both-catalysts are effective, and a large furan diversity can be obtained in high yield with one or the other catalyst. Mechanistic studies revealed that a cascade pathway and not the sometimes reported direct intra molecular nucleophilic addition of oxirane oxygen atom to intermediate acetylene-metal pi-complex occurs. Under the defined conditions, the intermediate formation of epoxide opening products has been identified. Depending on the catalyst, one or both of the latter cyclized to dihydrofurans, and further elimination of the alcohol led to the corresponding furans. These results highlight the duality between oxophilicity and alkynophilicity of Ag or Au salts.
Marshall, James A.; Dubay, William J., Journal of the American Chemical Society, 1992, vol. 114, # 4, p. 1450 - 1456
作者:Marshall, James A.、Dubay, William J.
DOI:——
日期:——
Gold Catalysis: Mild Conditions for the Transformation of Alkynyl Epoxides to Furans
作者:A. Stephen K. Hashmi、Pradipta Sinha
DOI:10.1002/adsc.200303201
日期:2004.3
Gold(III) chloride catalyzes the isomerization of alkynylepoxides to furans under mildconditions. Additional functional groups like hydroxy groups or aryl bromides do not need to be protected.