The Stabilizing Role of the Intramolecular C–H···O Hydrogen Bond in Cyclic Amides Derived From α‑Methylbenzylamine

A series of five-, six-, seven-, and eight-membered lactams containing the chiral auxiliary α-methylbenzylamine were structurally analyzed and further studied by DFT calculations with the purpose to examine with detail the previously detected intramolecular C–H···O hydrogen-bonding interaction formed between the hydrogen atom of the α-methylbenzylamine and the carbonyl group of the cyclic amide. The main objective was to establish whether its presence does have a tangible relevance in their spatial arrangement in solution and in the solid state or is a simple and not stabilizing interaction.