Abstract: Modern cross-couplings of arylmagnesium bromides with dibromoarenes gave 3, 3'''-dimethylquaterphenyl and, from its dibromination product, 2', 3''''-dimethyl-p-sexiphenyl (DMSP) in high yield with use of the air-stable PdCl2∑ dppb in catalytic amount. Arylboronic acids need not be prepared as intermediates, and use of pyrophoric aryllithiums was avoided. DMSP is a useful scintillation fluor with high stability and fast response time. Key ...