Camphane-based aminophosphine ligands for Pd-catalyzed asymmetric allylic alkylation

A practical synthesis of new chiral aminophosphine ligands based on the camphane scaffold bearing alkoxy groups was accomplished. The application of these ligands in the Pd-catalyzed allylic alkylation of (E)-1,3-diphenyl-2-propenyl acetate proceeded with excellent conversions and ee’s of up to 91%. Variation of the alkoxy substituents did not substantially influence the catalytic performance.

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(1S,2R,3S,4R)-N-(2-(Diphenylphosphino)benzyl)-3-ethoxy-N-ethyl-4,7,7-trimethylbicyclo[2.2.1]heptan-2-amineC33H42NOPDe >99% (NMR)[α]D20=+54.9 (c 0.85, CHCl3)Source of chirality: (+)-camphorAbsolute configuration: (1S,2R,3S,4R)

(1S,2R,3S,4R)-3-Butoxy-N-(2-(diphenylphosphino)benzyl)-N-ethyl-4,7,7-trimethylbicyclo[2.2.1]heptan-2-amineC35H46NOPDe >99% (NMR)[α]D20=+46.1 (c 0.31, CHCl3)Source of chirality: (+)-camphorAbsolute configuration: (1S,2R,3S,4R)

(1S,2R,3S,4R)-3-(Benzyloxy)-N-(2-(diphenylphosphino)benzyl)-N-ethyl-4,7,7-trimethylbicyclo[2.2.1]heptan-2-amineC38H44NOPDe >99% (NMR)[α]D20=+63.8 (c 0.0.50, CHCl3)Source of chirality: (+)-camphorAbsolute configuration: (1S,2R,3S,4R)