Synthesis and Structure of 2-Cyclohexylamino-3-methyl-1,1-diphenyl-butan-1-ol (d-N-Cyclohexyl-diphenylvalinol), an Amino Alcohol Ligand Useful in Asymmetric Catalysis

Amino alcohols are important ligands for the asymmetric catalytic hydroamination of aminoallenes to form chiral pyrrolidines. The amino alcohol d-N-cyclohexyl-diphenylvalinol was synthesized and crystallized by slow evaporation from a 7:1 ether:ethanol mixture. The molecule crystallizes in the monoclinic space group P2 1 with unit cell parameters a = 8.0724(8) A, b = 14.4327(14) A, c = 8.6752(9) A and β = 107.098(2)° and contains one molecule in the asymmetric unit with all constituent atoms being on general positions. Close inspection of the solid-state structure revealed a strong intramolecular hydrogen bond between the hydrogen atom of the hydroxyl group and the amine nitrogen. Herein we report the solid state structure of the chiral amino alcohol D-N-cyclohexyl-diphenylvalinol, a molecule which can serve as a ligand for transition metal complexes that function as asymmetric hydroamination catalysts .