Gold(I)-Catalyzed Synthesis of γ-Hydroxyketones from 5-Allyloxy-1-ynes

Abstract

The Au(I)-catalyzed reactions of 5-allyloxy-1-ynes gave various γ-hydroxyketones, via a hydration-terminated domino sequence involving sigmatropic allyl migration as the key event. Moreover, the scope of the sigmatropic allyl transfer was systematically determined.

Gold-catalyzed intermolecular coupling of sulfonylacetylene with allyl ethers: [3,3]- and [1,3]-rearrangements

“…Finally, R 4 substituent at the allyl group ( 2n ) retarded the transformation severely, indicating an unfavorable steric interaction. Unlike previous intramolecular [3,3]-sigmatropic rearrangements [13–14], the γ,γ-disubstituted allyl ethers derived from geraniol or nerol were completely inactive, most probably due to steric reasons as in the case of 2d .…”

Gold‐Catalyzed 1,4‐Carbooxygenation of 3‐En‐1‐ynamides with Allylic and Propargylic Alcohols via Non‐Claisen Pathways

“…This model rationalizes well the side products of some catalysts in Table ; enolate C bearing electron‐rich IPrAu tends to undergo protonation to form hydration products 1a‐H or 1a‐H′ (entry 5). For Zn(OTf) 2 , its vinyl propargyl ether B is expected to release HOTf to form a dual acid species D , thus giving additional Clasien product 6c (entry 6).…”

Gold‐Catalyzed Allylation Reactions

“…Rhee and co‐workers exploited the nucleophilic trapping of a cationic gold intermediate ( XVII ) to convert the 5‐allyloxy‐1‐yne 59 into the corresponding γ‐hydroxyketone 60 , via a hydration‐terminated domino sequence involving alkoxycyclization/sigmatropic allyl migration (Scheme a) . An analogous 5‐ exo ‐dig approach applied to ynenyl allyl ethers 62 furnished substituted furans 63 , bearing a quaternary stereocenter (Scheme b) .…”

“…The intra-and intermolecularn ucleophilic addition of oxygenated functions to gold-activated alkynes has been widely exploited to generatea llyl vinyl oxonium species that can evolve through concerted or stepwiser earrangements.I np articular, the intramolecular addition of ethers to gold-activated triple Rhee and co-workerse xploited the nucleophilic trapping of ac ationic gold intermediate (XVII)t oc onvert the 5-allyloxy-1yne 59 into the corresponding g-hydroxyketone 60,via ahydration-terminated domino sequence involving alkoxycyclization/ sigmatropic allyl migration (Scheme 17 a). [43] An analogous 5exo-dig approach applied to ynenyl allyl ethers 62 furnished substituted furans 63,b earing aq uaternary stereocenter (Scheme 17 b). [44] Hashmi and co-workers developed ac omple-mentary6 -endo-dig strategy,a llowing internal ynenyl allyl ethers 64 to be transformed into 1,3,6-trien-4-yl ketones 65 by means of a [ 3,3]-sigmatropicr earrangement and as ubsequent electrocyclic ring opening( Scheme 17 c).…”