P-Stereogenic monophosphines in Pd-catalysed enantioselective hydrovinylation of styrene

Two groups of P-stereogenic monodentate phosphines containing pendant groups bearing functionalities capable of having secondary interactions, PArPhR -1,1′-biphenylyl] and R = OMe or Me ) and PMeR(CH2R′), SiMe2Ph or CH2(2-naphthyl) ) have been prepared in enantiomerically pure form by the Jugé and Evans methodologies and characterised, including the crystal structure for the borane adduct of 12b

Arnald Grabulosa; Alberto Mannu; Guillermo Muller; Teresa Calvet; Mercè Font-Bardia

2011

Key concepts

Scholarcy highlights

  • Two groups of P-stereogenic monodentate phosphines containing pendant groups bearing functionalities capable of having secondary interactions, PArPhR-1,1′-biphenylyl] and R = OMe or Me) and PMeR(CH2R′), SiMe2Ph or CH2(2-naphthyl)) have been prepared in enantiomerically pure form by the Jugé and Evans methodologies and characterised, including the crystal structure for the borane adduct of 12b
  • Reaction of the phosphines with the Pd dimer2 produced neutral allylic complexes C, which have been characterised in solution and shown to be a mixture of isomers with different absolute configuration at the Pd atom
  • After abstraction of the chloride ligand by AgBF4, the solutions of cationic complexes have been used as catalyst precursors in the hydrovinylation of styrene under mild conditions
  • Deep differences in the activity and enantioselectivity have been found depending on the structure of the ligand
  • In spite of that the results did not permit to confirm the improvement of the selectivities of the reaction by stabilization of the catalyst through secondary coordination with the potentially hemilabile ligands
  • Ligand effects on the activity and stereoselectivity have been observed but do not confirm the potential hemilability of the ligands

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