Proton magnetic resonance studies of compounds with bridgehead nitrogen atoms—XXIV: The stereochemistry of octahydroimidazo [1,5-a] pyridine and of some N-acetyloctahydroimidazo [1,5-a] pyridines

Octahydroimidazo1,5-a]pyridine is shown to preferentially adopt the trans-fused ring conformation in solution at room temperature. The NMR spectra of the rotational isomers of some N-acetyloctahydroimidazo1,5-a]pyridines and N-acetyloctahydro-1H-pyrido1,2-c]pyrimidine are described, and the stereochemistry about the N-acetyl bonds and the cis or trans nature of the ring fusion defined.