Atropisomerism in 3,4,5-Tri-(2-methoxyphenyl)-2,6-lutidine

Suzuki reaction of tribromo-2,6-lutidine with (2-methoxyphenyl)boronic acid gave 3,4,5-tris(2-methoxyphenyl)-2,6-lutidine in the form of a mixture of three atropisomers that were stable at room temperature. Each isomer was isolated and fully characterized, including by X-ray structure determination. One of the isomers, being a racemic mixture, was separated into individual enantiomers by using semipreparative chiral HPLC. Their absolute stereochemistry was initially assigned on the basis of computational calculation of the CD spectra and finally confirmed by X-ray analysis.