The title compound, C19H19NO5, (I), is the product of a domino reaction between cotarnine chloride and acetyl-acetylene catalysed by copper(I) iodide. The mol-ecule of (I) comprises a fused tetra-cyclic system containing two terminal five-membered rings (pyrrole and 1,3-dioxole) and two central six-membered rings (di-hydro-pyridine and benzene). The five-membered 1,3-dioxole ring has an envelope conformation and the central six-membered di-hydro-pyridine ring adopts a twist-boat conformation. The acyl substituent is almost coplanar with the pyrrole ring, whereas the meth-oxy substituent is twisted by 27.93 (16)° relative to the benzene ring. The 2-oxopropan-1-yl substituent is roughly perpendicular to the pyrrole ring. In the crystal, mol-ecules are stacked along the a-axis direction; the stacks are linked by weak C-H⋯O hydrogen bonds into puckered layers lying parallel to (001).
Keywords: alkaloids; cotarnine; crystal structure; dihydropyrrolo[2,1-a]isoquinolines; domino reaction; lamellarin.