Crystal structure of 3-methoxycarbonyl-2-(4-methoxypheny1)-8-oxo-1-azaspiro-[4.5]deca-1,6,9-trien-1-ium-1-olate

The title compound, C18H17NO5, was prepared by a synthetic strategy based on the Heck reaction from Morita-Baylis-Hillman adducts. The five-membered ring adopts a slightly twisted conformation on the C-a-C-m (a = aromatic and m = methylene) bond. The dihedral angle between the five membered ring and the spiro aromatic ring is 89.35 (7)degrees; that between the five-membered ring and the 4-methoxybenzene ring is 4.65 (7)degrees. Two short intramolecular C-H center dot center dot center dot O contacts occur. In the crystal, molecules are linked by C-H center dot center dot center dot O hydrogen bonds to generate a three-dimensional network.