ABSTRACT
Direct metal-free C-4-selective indolation of pyridines is achieved for the first time using TEMPO and (Boc)2O. A variety of substituents on both indoles and pyridines are tolerated to give 3-(pyridin-4-yl)-1H-indole derivatives in moderate to excellent yields. This finding provides a novel approach for developing metal-free C-H functionalization of pyridines.
Subject(s)
Carbonates/chemistry , Cyclic N-Oxides/chemistry , Indoles/chemistry , Metals/chemistry , Pyridines/chemistry , Alkylation , Oxidation-Reduction , StereoisomerismABSTRACT
A general and efficient method for the cross-coupling of indoles with ß-keto esters by using TEMPO/CuSO4·5H2O in air as oxidant has been developed. This reaction features high functional-group compatibility and an excellent selectivity. This methodology provides an alternative approach for the ketonization-olefination of indoles in moderate to good yields.
Subject(s)
Alkenes/chemical synthesis , Copper/chemistry , Indoles/chemistry , Ketones/chemical synthesis , Alkenes/chemistry , Catalysis , Cyclic N-Oxides/chemistry , Esters/chemistry , Ketones/chemistry , Molecular Structure , StereoisomerismABSTRACT
A simple, convenient and efficient metal-free catalyzed oxidative trimeric reaction of indoles toward a variety of 2-(1H-indol-3-yl)-2,3'-biindolin-3-one derivatives in moderate to excellent yields has been developed. This transformation proceeds via a tandem oxidative homocoupling reaction by using TEMPO in air as an environmentally benign oxidant. This methodology provides an alternative approach for the direct generation of all-carbon quaternary centers at the C3 position of indoles.
