Metal-Dependent Reactions of Bulky Metal(II) Amides M[N(SiMe3)2]2 with 3,3′-Disubstituted Binaphthols (HO)2C20H10(SiR3)2-3,3′: Selective Conversion of One Equivalent −OH Group to a Silyl Ether −OSiMe3

The outcome of the reaction of the bulky metal(II) amides M[N(SiMe3)2]2·nTHF (M = Be, Zn, Ge, Sn, n = 0; M = Mg, Ca, n = 2) with (R)-3,3′-bis(trimethylsilyl)-1,1′-bi-2,2′-naphthol ((R)-1) or (S)-3,3′-bis(dimethylphenylsilyl)-1,1′-bi-2,2′-naphthol ((S)-9) depends on the identity of the metal and the nature of the 3,3′-substituents. When M = Be, Zn, or Ge, these amides serve as useful silylation agents that convert only one of the equivalent hydroxyl groups of the binaphthol (R)-1 to a trimethylsilyl ether, whereas the reactions of (R)-1 with the Mg, Ca, or Sn amides generate a polynuclear complex. The reaction pathway for these interconversions was qualitatively monitored using NMR (1H and 9Be) spectroscopy. Treatment of Ge[N(SiMe3)2]2 with (S)-9 yields both a silyl ether and the chelated germanium(II) binaphthoxide (S)-[Ge{O2C20H10(SiMe2Ph)2-3,3′}{NH3}], which was structurally characterized.