Facultad de Humanidades y Ciencias de la Educación, Synthesis: Journal of Synthetic Organic Chemistry, 09(51), p. 2030-2038, 2019
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A straightforward approach toward a decorated cyclopenta[ij]isoquinoline embodying the ABC-ring system characteristic of the azafluoranthene (triclisine), tropoisoquinoline (pareitropone) and proaporphine (prodensiflorin B) alkaloids, is reported. The synthetic sequence entailed a novel 40% KF/Al2O3-mediated hydroacylation of a 2-allyl-benzaldehyde derivative, obtained in two steps from isovanillin, through O-allylation and Claisen rearrangement to assemble the AC-ring system. This was followed by an O-methylation and a reductive amination of the resulting indanone with aminoacetal. A modified Pomeranz–Fritsch cyclization was next implemented to install ring B, through sulfonamidation, followed by acid-promoted cyclization and final desulfonylation in situ.