The structure of the title compound, C(18)H(20)N(2)O, at 173 K has hexa-gonal (P6(1)) symmetry. The N-containing six-membered ring assumes a half-chair conformation. In the crystal, inter-molecular N-H⋯O hydrogen bonding via the amide groups cross-link the mol-ecules along the a axis. The absolute configuration was confirmed by 2D NMR studies.

The asymmetric unit of the title compound, C(3)H(5)N(5)O(2), contains three crystallograpically independent mol-ecules. In the crystal structure, inter-molecular N-H⋯N, N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

The asymmetric unit of the title compound, C(29)H(34)N(2)O, contains two mol-ecules in which the N-containing six-membered rings assume different conformations viz. half-chair and envelope. Inter-molecular N-H⋯O hydrogen bonding via the amide groups cross-link the mol-ecules in the crystal structure.

A chemical library of carboxamide-substituted tetramates designed by analogy with antibacterial natural products, a method for their rapid construction, and the evaluation of their antibacterial activity is reported.