847653-12-7Relevant academic research and scientific papers
PdII-catalysed C-H functionalisation of indoles and pyrroles assisted by the removable N-(2-pyridyl)sulfonyl group: C2-alkenylation and dehydrogenative homocoupling
Garcia-Rubia, Alfonso,Urones, Beatriz,Arrayas, Ramon Gomez,Carretero, Juan Carlos
scheme or table, p. 9676 - 9685 (2010/10/18)
The easily installed and removed N-(2-pyridyl)sulfonyl group exerts complete C2 regiocontrol over the PdII-catalysed C-H alkenylation of indoles and pyrroles, affording the corresponding products in good isolated yields (typically ≥ 70%). A remarkable feature of this catalyst system is that it tolerates a wide variety of substituted alkenes, including conjugated electrondeficient alkenes, styrenes and 1,3- dienes, as well as conjugated 1,1- and 1,2-disubstituted olefins. The final reductive desulfonylation affords the C2- substituted, free-NH indoles and pyrroles in good yield. This N-(2-pyridyl)- sulfonyl-directing strategy has also been extended to the development of a protocol for the intermolecular, dehydrogenative homocoupling of indoles, providing 2,2'-biindoles. Mechanistic work based upon reactions with isotopically labelled starting materials and competitive kinetic studies of electronically varied substrates suggests a chelation- assisted electrophilic aromatic substitution palladation mechanism.
