Synthesis of a novel spiro bisphosphinite ligand and its application in Rh-catalyzed asymmetric hydrogenation

A novel, chiral bisphosphinite ligand (R)-SpiroBIP has been synthesized. The rhodium complex of the ligand was found to be highly enantioselective in the asymmetric hydrogenation of α-dehydroamino acid derivatives.

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(1R,2R,1′R)-2,2′-Spirobiidan-1-((2S)-(O-tert-butyldimethylsilyl)mandeloxy)-1′-olC31H36O4SiEe ⩾99%[α]D20=-84.5 (c 10.640, 0.1 dm, chloroform)

(1R,2R,1′R)-2,2′-Spirobiidan-1,1′-diolC17H16O2Ee ⩾99%[α]D20=-50.3 (c 0.056, 1 dm, Sure/Seal TM acetone)

(1R,2R,1′R)-1,1′-Bis(diphenylphosphinoxy)-2,2′-spirobiindaneC41H34O2P2Ee ⩾99%[α]D20=+8.4 (c 0.154, CHCl3)