Ruthenium Catalyzed <i>ortho</i> C–H Alkenylation of β‐Carbolines and Isoquinolines Using Terminal Alkynes for the Extended π‐Systems and their Biological Evaluation
Santhanam Srinath, Durairaj Gopalakrishnan, Mani Ganeshpandian, R. N. Abinaya, Baburaj Baskar
Abstract
A systematic screening study on ortho C–H alkenylation of β‐carbolines with terminal alkynes using different transition metal catalysts is described. The investigation clearly shows that [Ru( p ‐cymene)Cl 2 ] 2 catalyst is suitable for the C–H alkenylation of β‐carbolines as the substrate as well as directing group. The selective formation of monoalkenylated products was accomplished in good to excellent yields. Various substrates with excellent functional group tolerance for C1‐phenyl/thienyl‐β‐carbolines and 6,7‐dimethoxyisoquinolines was demonstrated. A number of novel alkenylated β‐carbolines ( 3a–3m ) and 6,7‐dimethoxy isoquinolines ( 7a–7h ) was achieved in (63–85 %) and (81–89 %) yields respectively. Also, the newly synthesized alkenylated β‐carbolines and isoquinolines were investigated for their anticancer activity.