Pd-Catalyzed Intramolecular Indole C-H Addition To Nitriles

Transition-metal-catalyzed annulations via direct coupling of a C(sp~2)-H bond with C-C multiple bonds constitute a robust and appealing motive due to their high efficiencies in the construction of cyclic compounds which hold a vital position in modern organic chemistry.By contrast,catalytic transformations of this type involving C-H bond addition to polar unsaturated carbon-heteroatom bonds such as nitriles have been received less consideration.Fused polycyclic indoles including six-membered ring systems such as carbazoles,pyrido[1,2-a]indoles,and their partially saturated counterparts represent a prominent class of heterocyclic compounds with varied and often potential biological activity.In addition,corresponding medium-sized-ring analogues are also the constituents of a variety of natural products and pharmaceutical agents.Therefore,it is of great significance for the construction of these molecular architectures.In this dissertation,we have accomplished a diverse synthesis of indole-fused polycyclic derivatives by a Pd-catalyzed intramolecular cyclization of indoles bearing cyanohydrin units.This thesis includes the following contents:(1)We have developed a strategy for the skeletal diverse synthesis of fused indoles via Pd-catalyzed intramolecular C-H addition of indoles bearing cyanohydrin units at the C(3),C(2),and N(1)positions of nitriles.Under the optimal conditions,a diversity of functionalized tetrahydropyrido[1,2-a]indoles,partially saturated carbazoles can be prepared in good to excellent yields.In addition,fused indoles with seven-or eight-membered rings can also be prepared smoothly.(2)We have developed a strategy for the synthesis of aminocarbazoles via Pd-catalyzed intramolecular C-H addition of indoles bearing cyanohydrin units at the C(3),C(2)positions of nitriles.Under the optimal conditions,a diversity of functionalized aminocarbazoles can be prepared in good to excellent yields.