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Synthesis, Coordination Properties and Application of New N , N ‐Ligands Based on Bornyl and Binaphthylazepine Chiral Backbones in Palladium‐Catalyzed Allylic Substitution Reactions
Author(s) -
Bottari Giovanni,
Meduri Angelo,
Drommi Dario,
Brancatelli Giovanna,
Faraone Felice
Publication year - 2011
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.201100113
Subject(s) - chemistry , palladium , tsuji–trost reaction , enantioselective synthesis , imine , chirality (physics) , catalysis , allylic rearrangement , dimethyl malonate , substitution reaction , enantiomer , amine gas treating , medicinal chemistry , alkylation , stereochemistry , combinatorial chemistry , organic chemistry , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
Abstract The synthesis of new imine‐amine and diamine ligands, based on both the atropisomeric ( S a )‐ or ( R a )‐1,1′‐binaphthyl and ( R )‐bornyl backbones, and incorporating an ethylenediamino spacer, are reported. In addition, analogue ligands in which one chiral arm is replaced by the achiral NMe 2 group were synthesized. These N , N ‐ligands when coordinated to a palladium metal centre form highly enantioselective catalysts for the asymmetric allylic alkylation of rac ‐2‐acetoxy‐1,3‐diphenylpropene by dimethyl malonate. In one case, the synergic effect of the chirality elements in the palladium catalyst afforded the ( S ) substitution product with an enantiomeric excess ( ee ) of >99 %. Based on NMR studies of the active species in solution, a reliable explanation for the origin of the enantioselectivity of these palladium catalysts is also provided.