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Diphosphorus Ligands Containing a P‐Stereogenic Phosphane and a Chiral Phosphite or Phosphorodiamidite – Evaluation in Pd‐Catalysed Asymmetric Allylic Substitution Reactions
Author(s) -
Clavero Pau,
Grabulosa Arnald,
Rocamora Mercè,
Muller Guillermo,
FontBardia Mercè
Publication year - 2016
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201600550
Subject(s) - chemistry , dimethyl malonate , tsuji–trost reaction , phosphinite , benzylamine , amination , ligand (biochemistry) , medicinal chemistry , allylic rearrangement , stereocenter , substitution reaction , stereochemistry , enantiomer , diastereomer , phosphoramidite , enantioselective synthesis , catalysis , organic chemistry , dna , biochemistry , receptor , oligonucleotide
The synthesis of 14 new optically pure C 1 ‐symmetric phosphane–phosphinite ( 1 – 4 ), phosphane–phosphite ( 5 – 9 ) and phosphane–phosphorodiamidite ( 10 – 14 ) ligands is reported. The ligands were prepared through the condensation of (2‐hydroxyphenyl)phenylphosphanes PPh(2‐PhOH)R (R = Me, t Bu and Ph) with chlorodiisopropylphosphane ( 1 and 2 ), chlorodiphenylphosphane ( 3 and 4 ), the chlorodioxaphosphepine derived from both enantiomers of 1,1′‐bi‐2‐naphthol ( 5 – 9 ) and the chlorodiazaphosphepine derived from both enantiomers of N , N′ ‐dimethyl‐1,1′‐binaphthyl‐2,2′‐diamine ( 10 – 14 ) in the presence of a base. With these ligands, cationic Pd complexes of the type [Pd(η 3 ‐C 4 H 7 )(PP′)]PF 6 (Pd 1 –Pd 14 ) were obtained and characterised; the crystal structures of Pd 1 , Pd 2 and Pd 13 were obtained. In solution, the complexes are present as mixtures of two diastereomers because of the lack of symmetry of the ligand and the presence of the methallyl group. The Pd complexes catalyse the allylic alkylation with dimethyl malonate and the amination with benzylamine of the model substrate rac ‐3‐acetoxy‐1,3‐diphenyl‐1‐propene ( I ). For the alkylation, full conversions and good enantioselectivities (up to 96 % ee with Pd 14 ) were observed.