Olefin Insertion Reactivity of a (Phosphine-arenesulfonate)Palladium(II) Fluoride Complex
by Black, R. E.; Kilyanek, S. M.; Reinhart, E. D.; Jordan, R. F.
The synthesis of the phosphine-arenesulfonate Pd(II) fluoride complex (PO-OMe)PdF(lut) (2, PO-OMe = P(2-OMe-Ph)(2)(2-SO3-5-Me-Ph), lut = 2,6-lutidine) and its reactions with electron-deficient olefins are described. The reaction of (PO-OMe)PdBr(lut) (1) with AgF affords 2 as an 82:18 mixture of cis-P,F and trans-P,F isomers. 2 isomerizes to a 1:2 cis-P,F:trans-P,F equilibrium mixture in CD2Cl2 solution at room temperature in ca. 3 days. 2 reacts with vinyl fluoride (VF) to afford (PO-OMe)Pd(CH2CHF2)(lut) (3), which exists as the cis-P,C isomer. 2 reacts with vinyl bromide (VBr) to yield 1 and VF by initial fluoropalladation to form (PO-OMe)Pd(CH2CHBrF)(lut) (4, not observed) followed by beta-Br elimination. 2 reacts with vinyl acetate to yield (PO-OMe)Pd{CH2CHF(OAc)}(lut) (5), which reacts further to form the C bound enolate complex (PO-OMe)Pd{CH2C(=O)H}(lut) (6) and acetyl fluoride. 2 reacts with vinyl benzoate in an analogous fashion. DFT analysis of the reaction of the model complexes cis-P,F- and trans-P,F-(PH2O)PdF(py) (C1 and C2, PH2O- = o-PH2C6H4SO3-) with VF supports a mechanism involving substitution of lutidine by VF followed by migratory insertion into the Pd F bond. An alternative mechanism comprising substitution of fluoride by VF to generate (PO-OMe)Pd(VF)(lut)(+) and F-, followed by exo attack of F- on the bound VF was found to be energetically prohibitive. DFT analysis of the reaction of the model complexes cis-P,F- and trans-P,F-(PH2O)PdF(VBr) (C10 and C13) supports an insertion/beta-Br elimination mechanism.
- Journal
- Organometallics
- Volume
- 38
- Issue
- 21
- Year
- 2019
- Start Page
- 4250-4260
- URL
- https://dx.doi.org/10.1021/acs.organomet.9b00545
- ISBN/ISSN
- 1520-6041; 0276-7333
- DOI
- 10.1021/acs.organomet.9b00545