Gold‐Catalyzed Regioselective Meyer–Schuster Rearrangement and Ring Expansion Cascade Leading to α‐Hydroxy‐α‐vinylcyclopentanones

Abstract

Readily available cyclobutanols having a butyne‐1,4‐diol moiety underwent a sequential regioselective Meyer–Schuster rearrangement and 1,2‐shift, furnishing α‐hydroxy‐α‐vinylcyclopentanones. The reaction mechanism is consistent with the formation of an allenol intermediate that racemizes under the reaction conditions. Subsequent activation of the allenol leads to an enantio‐ and diastereoselective route to this scaffold.

Regio‐ and Site‐selective Molecular Rearrangements by Homogeneous Gold Catalysis

“…They exposed the Au(I)-catalyzed synthesis of several αhydroxy-α-vinylcyclopentanones 221 through an unprecedented Meyer Schuster/ring expansion cascade occurring through a hydrogen-bonding mechanism (Scheme 51, eq 3). [231] The same group also disclosed a tandem Au(I)-catalyzed regioselective hydration followed by a chemoselective α-ketol rearrangement of 1-alkynylcyclobutanol derivatives to form αoxygenated cyclopentanones. In this study, they showed that 5 mol% of Au(IPr)BF 4 in 1,4-dioxane induce the regioselective hydration prior to ring expansion and α-ketol rearrangement.…”

Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity

“…α,β-Unsaturated ketones can be efficiently prepared by a gold(I)-catalyzed Meyer-Schuster-like rearrangement from propargyl carboxylates 332 or alcohols. 333 In contrast, γ-hydroxy-α,β-acetylenic esters in the presence of alcohols undergo a gold(I)-catalyzed alkoxylation/lactonization to form 4-alkoxy-2(5 H )-furanones. 334 The gold(I)-catalyzed reaction of alkynylcyclopropanols and cyclobutanols proceeds through ring expansion to give α-alkylidene cyclobutanones.…”

Recent Developments in the Meyer‐Schuster Rearrangement

“…Another interesting example was a gold‐silver catalyzed MSR‐expansion cascade to obtain α‐hydroxy‐α‐vinyl cyclopentanones 133 starting from cyclobutyl alkyne 1,4‐diols 132 (Scheme 31). [79] …”

“…[78b] Another interesting example was a gold-silver catalyzed MSR-expansion cascade to obtain α-hydroxy-α-vinyl cyclopentanones 133 starting from cyclobutyl alkyne 1,4-diols 132 (Scheme 31). [79] In this process, the gold/silver (28 o + 29 c) -mediated MSR was followed immediately by a 1,2 shift to deliver the cyclopentanones. To support this mechanism, extensive studies have been performed using optically active starting materials, as well as labelling experiments.…”