Multistep Synthesis of a Terphenyl Derivative Showcasing the Diels–Alder Reaction

An adaptable multistep synthesis project designed for the culmination of a second-year organic chemistry laboratory course is described. The target compound is a terphenyl derivative that is an intermediate in the synthesis of compounds used in organic light-emitting devices. Students react a conjugated diene with dimethylacetylene dicarboxylate in a Diels–Alder reaction, then use enolate chemistry to isomerize and aromatize the adduct. Analysis of the synthesized intermediates and final compound is accomplished by thin-layer chromatography, NMR, and melting point. The synthesis can be expanded to four or five steps by linking to a previously published preparation of the diene. In addition to gaining experience with classic reactions in undergraduate organic chemistry courses, students are exposed to the utility of NMR spectroscopy by tracking subtle changes in the NMR spectra of structurally similar species.