Mechanistic features of the copper-free Sonogashira reaction from ESI-MS

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dc.contributor.author Ahmadi, Zohrab
dc.contributor.author Yunker, Lars P. E.
dc.contributor.author Oliver, Allen G.
dc.contributor.author McIndoe, J. Scott
dc.date.accessioned 2017-04-24T20:59:51Z
dc.date.available 2017-04-24T20:59:51Z
dc.date.copyright 2015 en_US
dc.date.issued 2015
dc.identifier.citation Ahmadi, Z., Yunker, L., Oliver, A., & McIndoe, J. (2015). Mechanistic features of the copper-free sonogashira reaction from ESI-MS. Dalton Transactions, 44(47), 20367-20375. en_US
dc.identifier.uri https://dx.doi.org/10.1039/C5DT02889B
dc.identifier.uri http://hdl.handle.net/1828/7978
dc.description.abstract The mechanism of the Sonogashira reaction in methanol was studied in detail using pressurized sample infusion electrospray ionization mass spectrometry (PSI-ESI-MS). Several key intermediates were identified and their structures were assigned by MS/MS studies. Cationic and anionic charged-tagged substrates were employed to look into the mechanism of this reaction from variety of angles. A reverse kinetic isotope effect was observed in which the reaction rate is accelerated in deuterated solvents (kH/kD = 0.6). The reaction was found to be zero order with respect to the aryl iodide and first order with respect to the phenylacetylene. A Hammett parameter of ρ = 1.4 indicates that the reaction is more favorable for aryl iodides with para EWGs. No evidence of product inhibition, dimerization of palladium catalyst, or agglomeration were observed. However, catalyst decomposition was inferred from a non-zero intercept in the plot of catalyst loading versus reaction rate. Monitoring the reaction by PSI-ESI-(-)MS on neutral and negatively charged substrates at variety of concentrations and conditions did not reveal any detectable anionic palladium complexes. Likewise no evidence of carbopalladation and relevant intermediates in the absence of a base was observed. en_US
dc.description.sponsorship NSERC en_US
dc.language.iso en en_US
dc.publisher Dalton Transactions en_US
dc.subject catalysis en_US
dc.subject mass spectrometry en_US
dc.subject electrospray ionization en_US
dc.subject real-time monitoring en_US
dc.subject Sonogashira coupling en_US
dc.subject Heck alkynylation en_US
dc.title Mechanistic features of the copper-free Sonogashira reaction from ESI-MS en_US
dc.type Postprint en_US
dc.description.scholarlevel Faculty en_US
dc.description.reviewstatus Reviewed en_US

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