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;
Asymmetric Construction of Nitrogen-Containing [2.2.2] Bicyclic Scaffolds Using <i>N</i>-(<i>p</i>-Dodecylphenylsulfonyl)-2-pyrrolidinecarboxamide
作者:Hua Yang、Rich G. Carter
DOI:10.1021/jo9009062
日期:2009.8.7
An organocatalyzed approach to enantioenriched isoquinuclidines and bicyclo[2.2.2]octanes via a p-dodecylphenylsulfonamide-modified proline catalyst has been developed. A series of aromatic imines have been explored for the formation of isoquinuclidines with high levels of enantioselectivity and diastereoselectivity, strongly favoring the exo product. A series of aliphatic imines has also been explored, which provide access to bicyclo[2.2.2]octanes through a novel mechanistic pathway in high levels of enantioselectivity and diastereoselectivity, favoring the endo product.