Rh(III)-catalyzed chelation-assisted C–H activation/annulation of 2-arylimidazolines with cyclic diazo-1,3-dicarbonyl compounds: a novel approach to tetracyclic annulated derivatives of 2,3-dihydroimidazo[2,1- <i>a</i> ]isoquinoline

2-Arylimidazolines were annulated with cyclic diazo-1,3-dicarbonyl compounds under Rh(III)-catalysis for the first time. The developed general and efficient approach based on CH-activation allowed the efficient preparation of five novel types of tetraheterocyclic systems derived from 2,3-dihydroimidazo[2,1- a ]isoquinolines fused with an additional five-, six- or seven-membered carbocycle or N -/ O -heterocycle.