title: Divergent reaction pathways of homologous and isosteric propargyl amides in sequential Ru/Pd-catalyzed annulations for the synthesis of heterocycles.
abstract: Cu-catalyzed three-component coupling of imines with benzoyl chloride and terminal arylalkynes followed by enyne ring-closing metathesis (RCM) and Heck cyclization afforded medicinally relevant benzoindolines, cyclopropane-fused indenopyridines, pyrroloquinolines, or 1,7-tetrahydrophenanthrolines via divergent cyclization pathways. Unexpectedly, the Pd-catalyzed cyclization of heterocyclic dienes proceeded via regiodivergent 5-exo or 6-endo pathways depending on the ring size (n = 1, 2) or the presence of isosteric groups (CH vs N). A one-pot protocol for the enyne-RCM/Heck annulation featuring a sequential addition of the Ru and Pd catalysts was developed maximizing the synthetic efficiency.
authors.affiliation: Department of Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, USA.
authors.forename: Sandeep N
authors.initials: SN
authors.lastname: Raikar
authors.forename: Helena C
authors.initials: HC
authors.lastname: Malinakova
mesh_terms: D000577:Amides / Q000737:chemistry*; D002384:Catalysis; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D010293:Pargyline / Q000031:analogs & derivatives* / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000577:Amides; D006571:Heterocyclic Compounds; D010165:Palladium; D012428:Ruthenium; D010293:Pargyline