Re catalysis in one‐pot reactions: An atom‐economical, one‐pot strategy that involves alkyne deprotonation and a subsequent rhenium(V)‐catalysed Meyer–Schuster rearrangement of the alkynol to provide α,ß‐unsaturated enones in high yield has been developed (see scheme). Subsequent in situ hydride reduction or Diels–Alder reaction of the enones provided products in good‐to‐high overall yields.
We report herein the facile and practical construction of α,β-unsaturatedketones via rhodium-catalyzed direct acylation of vinylsilanes with readily available and abundant carboxylic acids. This protocol features access to a diverse array of synthetically useful functionalities with moderate to excellent yields. More importantly, the late-stage functionalization of pharmaceuticals was also realized
Rearrangement of Allylic and Propargylic Alcohols Catalyzed by the Combined Use of tetrabutylammonium perrhenate (VII) and p-toluenesulfonic acid
作者:Koichi Narasaka、Hiroyuki Kusama、Yujiro Hayashi
DOI:10.1016/s0040-4020(01)88874-8
日期:1992.1
Allylic rearrangement and/or dehydration reaction of allylic alcohols proceeds smoothly by the use of catalytic amounts of tetrabutylammonium perrhenate and p-toluenesulfonic acid hydrate. Treatment of propargylic alcohols with the catalysts at room temperature affords the rearranged products, α,β-unsaturated carbonyl compounds, while, β,γ-unsaturated ketones are obtained as main products by the reaction
2-Benzothiazolyl Propargyl Sulfides: Versatile Precursors for Enantiopure Allenes, E-α,β-Unsaturated Ketones and Z-Sulfonylalkenes
作者:Dagmar Kapeller、Philip Kocienski
DOI:10.1055/s-0030-1258259
日期:2010.11
described. The approach proceeds via a retro-ene reaction, initiated by lithium aluminium hydride mediated cleavage of benzothiazole from the respective (chiral) 2-benzothiazolyl propargyl sulfone precursors. As such, allenes in up to 92% yield are formed under evolution of sulfur dioxide at ambienttemperature. Furthermore, a new and mild way to generate E-α,β-unsaturated ketones has been discovered. These
The combination of Mo and cationic Au catalysts dramatically accelerated the rearrangement of diverse propargyl alcohols, which includes a short reaction time, mild conditions, and high product yields. A practical application to the highly challenging primary propargyl alcohols and the N-alkynyl amides is achieved.