Synthesis of a (piperazin-1-ylmethyl)biaryl library via microwave-mediated Suzuki–Miyaura cross-couplings

A library of (piperazin-1-ylmethyl)biaryls has been synthesized from tert-butyl 4-(3- and 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)piperazine-1-carboxylates. The resulting boronic acid pinacol esters can react in a Suzuki coupling with arylbromides such as 1-bromo-2-, 3- or 4-nitrobenzene or 2-bromo-5-nitropyridine to form the corresponding biaryls. Judicial removal of the protecting group on the piperazine or facile reduction of the nitro group in the biaryl system enables the manipulation of two points of functionality in order to diversify the scope of the resulting biaryl scaffold