Gold‐Catalyzed Tandem Cycloisomerization of Alkynyloxiranes with Nucleophiles: An Efficient Approach to 2,5‐Disubstituted Furans

Abstract

An efficient approach to 2,5-disubstituted furans has been developed by utilizing gold-catalyzed sequential nucleophilic attack onto metal-complexed alkynes with complete regioselectivity. The reaction proceeds efficiently under mild conditions with commercially available catalysts to afford furans in moderate to excellent yields (up to 96 %) with high diversity.

Metalltriflimidate sind bessere Katalysatoren für die organische Synthese als Metalltriflate – der Effekt eines stark delokalisierten Gegenions

“…[143][144][145] Gold(I)-triflimidate scheinen eine bevorzugte Katalysatorklasse für die Cycloisomerisierung von 2-Alkinylarylepoxiden zu 3-Acylindenen zu sein. [146] À -Komplex erhalten.…”

Gold in Homogeneous Catalysis

“…376 Thus, an initial example observed in nature is the existence of Au atoms in the core of a bacterial protein that oxidizes methane to methanol. 377 In a reaction that tries to mimic this behavior, the formation of alkyl hydroperoxides was achieved with NaAuCl 4 or [AuCl(PPh 3 )] in acetonitrile solution with H 2 O 2 at relatively low temperatures (75 • C). 378 The formed hydroperoxides decomposed partially in the reaction mixture to give the corresponding alcohols and ketones, but were subsequently reduced to the alcohols by different methods.…”

Metal-catalyzed Furan Synthesis. A Review

“…Liang and co-workers reported a gold-catalyzed approach to furans from 1-oxiranyl-2-alkynyl esters and a range of nucleophiles including alcohols, furans and pyrroles (Scheme 5). 19,20 The reaction is proposed to proceed through activation of the alkyne by the gold species followed by nucleophilic attack by the epoxide oxygen with either pre-or post-opening of the three-membered ring with water. Protiodeauration and aromatization through loss of acetic acid provides the furan ring which loses water by gold catalysis to generate a carbocationic intermediate which is trapped 6 by a nucleophile.…”