Methyl 2-benzamido-4-(3,4-dimethoxyphenyl)-5-methylbenzoate, C(24)H(23)NO(5), (Ia), and N-{5-benzoyl-2-[(Z)-2-methoxyethenyl]-4-methylphenyl}benzamide, C(24)H(21)NO(3), (IIa), were formed via a Diels-Alder reaction of appropriately substituted 2H-pyran-2-ones and methyl propiolate or (Z)-1-methoxybut-1-en-3-yne, respectively. Each of these cycloadditions might yield two different regioisomers, but just one was obtained in each case. In (Ia), an intramolecular N-H···O hydrogen bond closes a six-membered ring. A chain is formed due to aromatic π-π interactions, and a three-dimensional framework structure is formed by a combination of C-H···O and C-H···π(arene) hydrogen bonds. Compound (IIa) was formed not only regioselectively but also chemoselectively, with just the triple bond reacting and the double bond remaining unchanged. Compound (IIa) crystallizes as N-H···O hydrogen-bonded dimers stabilized by aromatic π-π interactions. Dimers of (IIa) are connected into a chain by weak C-H···π(arene) interactions.
© 2011 International Union of Crystallography