Reaction of 1,2-dihaloarenes with ethyl 2-(imidazolidin-2-ylidene)acetate. A novel method for the synthesis of 2,3-dihydro-1H-imidazo[1,2-a]indoles and their aza analogs

Cs2CO3-promoted [3 + 2] cycloaddition providing an easy protocol toward imidazo[1,2-a]indole derivatives

“…6 Although these fused imidazo[1,2-a]indoles showed important biological activities, efficient and practical approaches to these molecules have been rarely documented. There are some limited methods for the assembly of imidazo[1,2-a]indoles, which suffer from the tedious steps, 7 low efficiency, 7,8 and/or the narrow substrate scopes. 9 Hence, the exploration of new, facile and versatile method for forming functionalized imidazo[1,2-a]indoles from readily available starting materials is still highly desired but full of challenge.…”