Transition‐Metal‐Catalyzed Propargylic Substitution of Propargylic Alcohol Derivatives Bearing an Internal Alkyne Group

Abstract

The development of the transition-metal-catalyzed propargylic substitution of propargylic alcohol derivatives is one of the active research subjects in organic synthesis. In this minireview, we summarize the catalytic propargylic substitution of propargylic alcohol derivatives bearing an internal alkyne group using a transition metal as the catalyst. Although the asymmetric propargylic substitution of the substrate class still underdeveloped, some transition metal catalyses using nickel, palladium, and copper, and the cooperative catalysis enabled the challenging transformation. A various types of transition-metal catalysts are known to promote the non-asymmetric propargylic substitution of the internal alkyne-substituted propargylic alcohol derivatives via a propargylic cation intermediate, realizing the carboncarbon and carbon-heteroatom bond formation at the propargylic position.

Photo and copper dual catalysis for allene syntheses from propargylic derivatives via one-electron process

“…1a ). However, scope and selectivity limitation remain due to the issues of the intrinsic two-electron mechanism 54 – 56 . Allenenitriles have been frequently employed as useful synthetic precursors for various organic motifs 57 – 59 , while the classic synthetic method relies on stoichiometric amount of CuCN-mediated cyanation of propargylic alcohols with KCN (1.5 equiv) in the presence of HBr (2.5 equiv) 60 .…”

Ni/Chiral Sodium Carboxylate Dual Catalyzed Asymmetric O-Propargylation

“…Asymmetric propargylic substitution (APS) reaction is one of the most fundamental reactions in organic chemistry, − and the stereoselective installation of alkyne groups could prime them for various addition manipulations in pharmaceuticals and medicinal chemistry . APS reaction has gained considerable interest as a practical approach for the rapid formation of molecular complexity in natural product synthesis .…”

Ni-Catalyzed Decarboxylative Silylation of Alkynyl Carbonates: Access to Chiral Allenes via Enantiospecific Conversions

“…It is generally accepted that a metal­(allenylidene) species plays a key role in the mechanistic scenario when a propargylic substrate containing a terminal alkyne is converted. , Such a manifold is obviously not feasible for propargylic precursors that have internal triple bonds, and their metal-catalyzed activation and conversion is suggested to involve a propargylic carbocation by a formal S N 2 displacement of the leaving group. Despite being distinct, for the latter category of propargylic substitutions several enantioselective protocols have evolved over the past decade .…”

“…In both cases, there is a key β-O-elimination step that empowers the propargylic substitution process. However, carbometalation followed by β-O-elimination is unprecedented with Ni, while Ni-promoted propargylic silylation to our knowledge remains unknown despite the report of several successful Ni-catalyzed propargylic substitution processes using amine and carbon pronucleophiles (Scheme b). ,,, …”