Gold(I)-Catalyzed Tandem Alkoxylation/Lactonization of γ-Hydroxy-α,β-Acetylenic Esters

Ruben Stefan Ramon Müller, Christophe Pottier, Adrian Gomez Suarez, Steven Patrick Nolan

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26 Citations (Scopus)

Abstract

The formation of 4-alkoxy-2(5H)-furanones was achieved via tandem alkoxylation/lactonization of g-hydroxy-a,b-acetylenic esters catalyzed by
2 mol% of [2,6-bis(diisopropylphenyl)imidazol-2-ylidine] gold bis(trifluoromethanesulfonyl)imidate [Au(IPr)(NTf2)]. The economic and simple procedure was applied to a series of various secondary propargylic alcohols allowing for yields of desired product of up to 95%. In addition, tertiary propargylic alcohols bearing mostly cyclic substituents were converted into the corresponding spiro derivatives. Both primary and secondary alcohols reacted with propargylic alcohols at moderate temperatures (65– 80 8C) in either neat reactions or using 1,2-dichloroethane as a reaction medium allowing for yields of
23–95%. In contrast to [Au(IPr)(NTf2)], reactions with cationic complexes such as [2,6-bis(diisopropylphenyl) imidazol-2-ylidine](acetonitrile)gold tetrafluoroborate
[Au(IPr)(CH3CN)][BF4] or (mhydroxy) bis{[2,6-bis(diisopropylphenyl)imidazol-2-
ylidine]gold} tetrafluoroborate or bis(trifluorometh- anesulfonyl)imidate – [{Au(IPr)}2(m-OH)][X] (X= BF4, NTf2) – mostly stop after the alkoxylation.
Analysis of the intermediate proved the exclusive formation of the E-isomer which allows for the subsequent lactonization.
Original languageEnglish
Pages (from-to)1575-1583
Number of pages9
JournalAdvanced Synthesis & Catalysis
Volume353
Early online date16 Jun 2011
DOIs
Publication statusPublished - 2011

Keywords

  • alkoxylation; catalysis; furanones; gold; N-heterocyclic carbenes

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