A new approach to alkaloid-like systems: synthesis and crystal structure of 1-(2-acetyl-11-methoxy-5,6-dihydro[1,3]dioxolo[4,5-g]pyrrolo[2,1-a]isoquinolin-1-yl)propan-2-one

Abstract

The title compound, C19H19NO5, (I), is the product of a domino reaction between cotarnine chloride and acetylacetylene catalysed by copper(I) iodide. The molecule of (I) comprises a fused tetracyclic system containing two terminal five-membered rings (pyrrole and 1,3-dioxole) and two central six-membered rings (dihydropyridine and benzene). The five-membered 1,3-dioxole ring has an envelope conformation and the central six-membered dihydropyridine ring adopts a twist-boat conformation. The acyl substituent is almost coplanar with the pyrrole ring, whereas the methoxy 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, molecules 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
• lamellarin
• cotarnine
• dihydropyrrolo[2,1-a]isoquinolines
• domino reaction
• crystal structure