Au(I) Catalyzed Synthesis of Densely Substituted Pyrazolines and Dihydropyridines via Sequential Aza-Enyne Metathesis/6π-Electrocyclization
Kenji Sugimoto, Shuto Kosuge, Takae Sugita, Yuka Miura, Kiyoshi Tsuge, Yûji Matsuya
Abstract
A gold(I) autotandem catalysis protocol is reported for the de novo synthesis of densely substituted pyrazolines and dihydropyridines from the corresponding imine derivatives in a highly regioselective fashion via a one-pot aza-enyne metathesis/6π-electrocyclization sequence. The substituents on the nitrogen atom of the imine perfectly control the reaction pathways from the pivotal 1-azabutadiene intermediate; thus, carbazates were converted into pyrazolines via 6π-electrocyclization of α,β-unsaturated hydrazones, while aryl imines provided dihydropyridines via 6π-electrocyclization of 3-azahexatrienes.
Topics & Concepts
ChemistryImineEnyne metathesisNitrogen atomRegioselectivityCatalysisMetathesisCombinatorial chemistryArylSalt metathesis reactionMedicinal chemistryOrganic chemistryRing (chemistry)AlkylPolymerPolymerizationSynthetic Organic Chemistry MethodsCatalytic Alkyne ReactionsCyclopropane Reaction Mechanisms