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Two-stage catalysis in the Pd-catalyzed formation of 2,2,2-trifluoroethyl-substituted acrylamides: oxidative alkylation of PdII by an IIII reagent and roles for acetate, triflate, and triflic acid
journal contribution
posted on 2023-05-21, 05:46 authored by Allan CantyAllan Canty, Alireza AriafardAlireza AriafardIn the synthesis of 2,2,2-trifluoroethyl-substituted acrylamides, two-stage palladium-catalysis is indicated experimentally, including oxidative alkylation of PdII to PdIV by [IIIIMes(CH2CF3)]+ (Besset et al., Chem. Commun., 2021, 57, 6241). For N-(quinolin-8-yl)-2-(phenyl)acrylamide [LH2 = H2C═C(Ph)–C(O)–NH∼N], studied by density functional theory herein, the first stage involves palladium acetate-promoted NH-deprotonation and concerted metalation-deprotonation CH-activation for Pd(OAc)2(LH2), followed by the transfer of [CH2CF3]+ from IIII to give a PdIV intermediate that undergoes reductive elimination to form the acrylamide-CH2CF3 linkage. The second stage employs [Pd(LH)(NCMe)]+ as the catalyst, with steps including outer-sphere CH-activation by triflate and crucial roles for PdIV, acetonitrile solvent, and N-protonation of the product by triflic acid to form [LH2(CH2CF3)]+. In an apparently unique process, the first stage is faster than the second and produces the catalyst, but the second stage is catalytic to provide high yields of the product.
History
Publication title
OrganometallicsVolume
41Pagination
293-300ISSN
0276-7333Department/School
School of Natural SciencesPublisher
Amer Chemical SocPlace of publication
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