Dibenzoacridines: synthesis by alkyne–carbonyl-metathesis and properties

Abstract

Dibenzo[a,j]acridines and regioisomeric dibenzo[c,h]acridines were synthesized from a common starting material, 2,3,5,6-tetrachloropyridine, by combination of site-selective cross-coupling reaction followed by ring-closing alkyne–carbonyl metathesis using simple Brønsted acids. The two regioisomeric series were accessed by change of the order of Sonogashira and Suzuki–Miyaura reactions. The optical properties of the products were studied by steady-state absorption spectroscopy and time-resolved emission measurements. The electronic properties of the products were further elucidated by DFT calculations.