A stepwise route to unsymmetrical tetraarylazadipyrromethenes by a condensation of 2, 4- diaryl-5-nitroso-pyrroles with 2, 4-diarylpyrroles is described. This modular building-block approach allows for the introduction of up to four different aryl substituents on the azadipyrromethene and is tolerant of a varied substituent set. An efficient synthesis of the 2, 4-diarylpyrroles building blocks from 1, 3-diaryl-4-nitro-butan-1-ones by nitro hydrolysis to ...