2-phenyl-1-boraadamantane complexes. Synthesis and intramolecular dynamics

Article abstract of DOI:10.1007/BF02494783

The reaction of triallylborane with 3-phenylprop-1-yne at 135 - 140 °C followed by treatment of the reaction mixture with MeOH afforded 7-benzyl-3-methoxy-3-borabicyclo[3.3.1]non-6-ene (1) in 81% yield. Hydroboration of compound 1 with a solution of BH₃ in THF yielded the tetrahydrofuran complex of 2-phenyl-1-boraadamantane (2). The reactions of trimethylamine or pyridine with compound 2 afforded the trimethylamine (3) or pyridine (4) complexes of 2-phenyl-1-boraadamantane, respectively. Hindered rotation about the C(2) - Ph bond in adduct 3 was observed by ¹H and ¹³C NMR spectroscopy. The activation energy of this process is 58.6 kJ mol^-1 (determined by 2D ¹H - ¹H EXSY spectroscopy).