Reactions of aryl and heteryl iodides with terminal acetylenes in the presence of co, catalyzed by palladium complexes

1991 ◽  
Vol 40 (11) ◽  
pp. 2224-2227
Author(s):  
A. B. Ponomarev ◽  
M. V. Shostakovskii ◽  
V. N. Kalinin
Keyword(s):  
Palladium Complexes ◽  
Terminal Acetylenes

Hydrostibination of Alkynes: A Radical Mechanism

2020 ◽  
Author(s):  
Josh MacMillan ◽  
Katherine Marczenko ◽  
Erin Johnson ◽  
Saurabh Chitnis
Keyword(s):  
Density Functional ◽  
Activation Barrier ◽  
Closed Shell ◽  
Reaction Rates ◽  
Radical Mechanism ◽  
Neutral Radical ◽  
Kinetic Isotope ◽  
Rate Limiting Step ◽  
Ionic Mechanisms ◽  
Terminal Acetylenes

The addition of Sb-H bonds to alkynes was reported recently as a new hydroelementation reaction that exclusively yields anti-Markovnikov <i>Z</i>-olefins from terminal acetylenes. We examine four possible mechanisms that are consistent with the observed stereochemical and regiochemical outcomes. A comprehensive analysis of solvent, substituent, isotope, additive, and temperature effects on hydrostibination reaction rates definitively refutes three ionic mechanisms involving closed-shell charged intermediates. Instead the data support a fourth pathway featuring neutral radical Sb<sup>II</sup> and Sb<sup>III</sup> intermediates. Density Functional Theory (DFT) calculations are consistent this model, predicting an activation barrier that is within 1 kcal mol<sup>-1</sup> of the experimental value (Eyring analysis) and a rate limiting step that is congruent with experimental kinetic isotope effect. We therefore conclude that hydrostibination of arylacetylenes is initiated by the generation of stibinyl radicals, which then participate in a cycle featuring Sb<sup>II</sup> and Sb<sup>III</sup> intermediates to yield the observed <i>Z</i>-olefins as products. This mechanistic understanding will enable rational evolution of hydrostibination as a methodology for accessing challenging products such as <i>E</i>-olefins.

Green and Facile Synthesis of 1,4-Disubstituted 1,2,3-Triazoles via a Click Reaction of α-Bromo Ketones, [bmim]N3 and Terminal Acetylenes

2013 ◽  
Vol 10 (10) ◽  
pp. 738-743 ◽  
Author(s):  
Azadeh Fazeli ◽  
Hossein Oskooie ◽  
Yahya Beheshtiha ◽  
Majid Heravi ◽  
Hassan Valizadeh
Keyword(s):  
Click Reaction ◽  
Facile Synthesis ◽  
Terminal Acetylenes
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