Synthesis and Structural Properties of Adamantane-Substituted Amines and Amides Containing an Additional Adamantane, Azaadamantane or Diamantane Moiety.

Introduction of adamantane moieties on diamondoids such as adamantane, 2-azaadamantane or diamantane by amide formation and reduction to the corresponding amine was performed in a straightforward and easy way by amidation under Schotten-Baumann conditions and reduction with BH  ⋅ THF. The obtained amides and amines were studied in terms of structural properties towards the perspective of transformation into nanodiamonds. Crystal structure and dynamic NMR experiments of the most crowded amide obtained gave structural insights into the effect of bulkiness and steric strain on out-of-planarity of amide bonds (16.0°) and the kinetics and thermodynamics of amide bond rotation (ΔG =11.5-13.3 kcal ⋅ mol ).