A highly efficient dual catalysis approach for C-glycosylation: addition of (o-azaaryl)carboxaldehyde to glycalsElectronic supplementary information (ESI) available: General experimental procedures and spectral charts of all products. See DOI: 10.1039/c4cc06111j

A novel and efficient dual catalysis approach by concurrent activation of glycals and ( o -azaaryl)-carboxaldehydes using palladium and N-heterocyclic carbene has been developed. The two electrophiles could react after activation through formation of the Breslow intermediate and a π-allyl Pd complex, widening the scope of reacting glycosylation partners and opening up possibilities for future glycosylation. Dual catalysis by concurrent activation of glycals and ( O -azaaryl)-carboxaldehydes using palladium and N-heterocyclic carbene has been developed. This activation through the formation of the Breslow intermediate and a π-allyl Pd complex is a novel and efficient approach to yield C -glycosides with yields up to 85%.