“…For instance, 25 mol% of GdCl 3 triggered the three-component reaction to deliver excellent yields of the corresponding THQs 516 and 517 with good diastereoselectivity (Scheme ). In addition, Sc(OTf) 3 , BF 3 ·OEt 2 , NbCl 5 , , Sm(OTf) 3 , ceric ammonium nitrate (CAN), CeCl 3 ·7H 2 O/NaI, and Al(OTf) 3 were also employed as catalysts for the same reaction. This chemistry was applied to the synthesis of hexahydro 2 H -pyrano[3,2- c ]quinolines as selective σ 1 receptor ligands .…”