Chiral Birch reduced tertiary phosphines: precursors to asymmetric 1,2-cyclohexenebis(tertiary phosphines)

Abstract

The first examples of an optically active Birch reduced tertiary phosphine, viz. (R_P)-(cyclohexa-2,5-dienyl)(3-pentyl)phenylphosphine, and successful hydrophosphination of the related racemic ligand (±)-(cyclohexa-2,5-dienyl)(2-propyl)phenylphosphine with PHPh₂ in the presence of KOBu^t in thf to give a 1,2-cyclohexenebis(tertiary phosphine), viz. (±)-1,2-C₆H₈(PPh₂)(PPhPrⁱ), are described; as confirmed by crystal structure determinations of [SP-4-4-(S_P,S)]-chloro[(cyclohexa-2,5-dienyl)(3-pentyl)phenylphosphine][2-{1-(dimethylamino)ethyl}phenyl-C,N]palladium(II) and [SP-4-3-(±)]-dimethyl[(1-diphenylphosphino)(2-isopropylphenylphosphino)cyclohexene]platinum(II).