Rationalized synthetic access to benzimidazoline based n-type dopant precursors

1H-benzimidazoline based molecular n-dopant precursors, such as 4-(2,3-Dihydro-1,3-dimethyl-1H-benzimid-azol-2-yl)-N,N-dimethylbenzenamine (N-DMBI-H), enable efficient doping of n-dopable organic semiconductors. Chemical modification of the molecular structure of such compounds proved to be a fundamental tool to tune their properties and doping efficiencies, according to the desired application. Versatile and efficient synthetic strategies, giving access to the widest range of substitution motifs, could help improve the access to known derivatives and enable the preparation of new and improved ones. Literature reports several syn-thetic approaches but due to lack of rationalization and a comprehen-sive analysis, the selection of that best suited for a specific target deriv-ative still mostly relies on a trial and error approach. In this work, we compare the features of the two most popular synthetic strategies in the preparation of a wide variety of benzimidazoline dopants having diverse substitution patterns and electronic features. We thus propose guidelines for the selection of the best synthetic approach depending on the characteristics of the target dopant, known as well as original.