om9b00545_si_001.pdf (4.41 MB)
Olefin Insertion Reactivity of a (Phosphine-arenesulfonate)Palladium(II) Fluoride Complex
journal contribution
posted on 2019-10-15, 19:40 authored by Rebecca
E. Black, Stefan M. Kilyanek, Erik D. Reinhart, Richard F. JordanThe
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 β-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/β-Br
elimination mechanism.