AI Article Synopsis
- The study investigates the differences in reactivity of various potassium aryltrifluoroborates in a silver-assisted palladium-catalyzed cross-coupling process.
- The role of silver(I) compounds in this reaction involves polarizing the Pd-X bond to enhance the transition state, which facilitates the reaction with weakly nucleophilic borates.
- The effectiveness of the silver reagents as polarizing agents varies, with Ag2O being the most efficient, but there is no clear link between the reactivity of the borates and the electron characteristics of their substituents.
Article Abstract
Small differences in the reactivity of weakly nucleophilic potassium aryltrifluoroborates are revealed in the silver-assisted Pd-catalyzed cross-coupling of K[4-RC6F4BF3] (R = H, Bu, MeO, EtO, PrO, iPrO, BuO, t-BuO, CH2=CHCH2O, PhCH2O, PhCH2CH2O, PhO, F, pyrazol-1-yl, pyrrol-1-yl, and indol-1-yl) with ArX (4-BrC6H4CH3, 4-IC6H4F and 3-IC6H4F). An assumed role of silver(I) compounds Ag m Y (Y = O, NO3, SO4, BF4, F) consists in polarization of the Pd-X bond in neutral complex ArPdL n X with the generation of the related transition state or formation of [ArPdL n ][XAg m Y] with a highly electrophilic cation and subsequent transmetallation with the weakly nucleophilic borate. Efficiency of Ag m Y as a polarizing agent decreases in order Ag2O > AgNO3 ≈ Ag2SO4 > Ag[BF4] > AgF. No clear correlation between the reactivity of K[4-RC6F4BF3] and substituent electron parameters, σI and σR°, of the aryl group 4-RC6F4 was found.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4464464 | PMC |
| http://dx.doi.org/10.3762/bjoc.11.68 | DOI Listing |
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