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Keywords:

  • carbenes;
  • enynes;
  • enantioselectivity;
  • isomerization;
  • phosphoramidites;
  • platinum

Abstract

The enantioselective cycloisomerization of 3-hydroxylated 1,5-enynes into bicyclo[3.1.0]hexanones was investigated by using cyclometalated NHC-platinum phosphoramidite complexes as pre-catalysts. Several new complexes were prepared. They generate cationic, electrophilic PtII species that efficiently promote the cycloisomerization process. Enantiomeric excesses up to 81 % were obtained in the reactions of enynes with aryl-substituted alkyne functions (8 examples, 70–81 % ee).