Construction of Tropane Derivatives by the Organocatalytic Asymmetric Dearomatization of Isoquinolines.

A chiral-NHC-catalyzed highly diastereo- and enantioselective dearomatizing double Mannich reaction of isoquinolines was developed that provides a powerful and straightforward synthetic route toward substituted tropane derivatives with four contiguous stereocenters. A unique feature of this strategy is the use of readily available isoquinolines to provide two reactive sites for dearomatization, thus opening up an unprecedented approach to tropane derivatives with excellent stereoselectivity. The four-component reactions proceeded smoothly with good results. Thus, the present method is suitable for the diversity-oriented synthesis of useful tropane derivatives with high efficiency.