anti-1,2-Diols via a Ni-Catalyzed Reductive Coupling
T. Luanphaisarnnont, C. O. Ndubaku, T. F. Jamison*
Massachusetts Institute of Technology, USA
21 September 2005 (online)
anti-1,2-Diols were prepared using a nickel-catalyzed reductive coupling of alkynes to α-oxyaldehydes. Both the MOM- and PMB-protected alcohols gave the anti-1,2-diol products despite the fact that these protecting groups typically display a preference for syn-1,2-diols. The observed sense of induction was explained by the absence of a chelating metal in the reaction allowing a ‘dipolar’ transition state to predominate. Larger substituents on the side of the alkyne where C-C bond formation occurs improves the diastereoselectivity but gives poorer yields. Heteroatom substituents on the alkyne are also tolerated.