Platinum and Ruthenium Chloride-Catalyzed Cycloisomerization of 1-Alkyl-2-ethynylbenzenes: Interception of π-Activated Alkynes with a Benzylic C−H Bond
摘要:
Air-stable and commercially available alkynophilic metal salts, such as PtCl2, PtCl4, and [RuCl2(CO)(3)](2), catalyze the cycloisomerization of 1-alkyl-2-ethynylbenzenes to produce Substituted indenes even at all ambient temperature. Electrophilically activated alkynes can be intercepted by simple benzylic C-H bonds at primary, secondary, and tertiary carbon centers. Mechanistic studies, such as labeling studies and kinetic isotope and substituent effects, indicate that the cycloisomerization proceeds through the formation of a vinylidene intermediate and turnover-limiting 1,5-shift of benzylic hydrogen.
Rh-Catalyzed Transannulation of <i>N</i>-Tosyl-1,2,3-Triazoles with Terminal Alkynes
作者:Buddhadeb Chattopadhyay、Vladimir Gevorgyan
DOI:10.1021/ol2014347
日期:2011.7.15
The first transannulation of 1,2,3-triazoles with terminal alkynes into pyrroles is reported. The reaction proceeds in the presence of a Rh2(oct)4/AgOCOCF3 binary catalyst system providing a straightforward approach to 1,2,4-trisubstituted pyrroles in good to excellent yields.
bond scission with conjunctive cross‐couplings, this decarboxylative reorganization reaction features fascinating atom and step economy and provides an efficientapproach to highlyfunctionalized dienynes from readily available substrates. Without further optimization, gram‐scale products can be easily obtained by such a simple, neutral, and low‐cost catalytic system with high TONs. DFT calculations
base‐promoted nucleophilic addition of arylacetonitriles to terminal alkynes has been described for the first time, providing a simple and straightforward protocol for the synthesis of a range of structurally diverse (Z)‐2,3‐disubstituted acrylonitriles in moderate to excellent yields. Of particular note, the transition metal‐free carbon‐carbon double bond forming reaction is regio‐ and stereoselective under
Alkynyl sulfoxides as α-sulfinyl carbene equivalents: gold-catalysed oxidative cyclopropanation
作者:Matthew J. Barrett、Ghulam F. Khan、Paul W. Davies、Richard S. Grainger
DOI:10.1039/c7cc02244a
日期:——
Alkynyl sulfoxides are shown to act as α-sulfinyl metallocarbene synthons under oxidative gold catalysis, enabling reactions that are not available from diazo-precursors. This strategy is exemplified in the synthesis of fused α-sulfinyl cyclopropanes.
Visible-light-promoted oxidative halogenation of alkynes
作者:Yiming Li、Tao Mou、Lingling Lu、Xuefeng Jiang
DOI:10.1039/c9cc07655g
日期:——
In nature, halogenation promotes the biological activity of secondary metabolites, especially geminal dihalogenation. Related natural molecules have been studied for decades. In recent years, their diversified vital activities have been explored for treating various diseases, which call for efficient and divergent synthetic strategies to facilitate drug discovery. Here we report a catalyst-free oxidative