Atropoisomerism in Mono- and Diaryl-Substituted 4-Amino-2,6-lutidines

The Suzuki–Miyaura reaction of 4‐amino‐3,5‐dibromo‐2,6‐lutidine with various ortho‐substituted phenylboronic acids resulted in the formation of a series of mono‐ and diarylated lutidines in the form of atropisomers. The absolute stereochemistry of the chiral compounds was established, in some cases, by X‐ray crystal structure analysis and HPLC‐ECD (ECD = electronic circular dichroism) in combination with time‐dependent density functional theory (TDDFT) calculations. The coupling reaction of 4‐amino‐3,5‐dibromo‐2,6‐lutidine with ortho‐substituted phenylboronic acids gave atropisomeric mixtures of aryl‐ and diaryl‐substituted derivatives. The absolute stereochemistry of the chiral isomers was confirmed by X‐ray crystal structure analysis and HPLC‐ECD (ECD = electronic circular dichroism) along with time‐dependent density functional theory (TDDFT) calculations.