New stable atropisomers derived from 2,4,6-collidine and related compounds

Joanna Szawkało, Dariusz Błachut, Piotr Roszkowski, Piotr Pomarański, Jan K. Maurin, Armand Budzianowski, Zbigniew Czarnocki

Tetrahedron, Volume: 72 Issue: 43 Pages: 6779-6787
DOI: 10.1016/j.tet.2016.08.086
Published: OCT 27 2016

Abstract

The Suzuki–Miyaura cross-coupling reaction of 3,5-dibromo-2,4,6-collidine and bromo derivatives of 2,6- and 2,4-lutidine with several ortho-substituted boronic acids produced a library of arylated pyridines. The reaction conditions were carefully optimized to allow high yield of the desired products. In several cases the presence of stable atropisomers were detected, even at elevated temperature during GC–MS analysis. Some of the diastereomers were isolated and characterized by spectroscopic methods and X-ray crystallography. Racemic forms of selected samples were tested by 1H NMR spectroscopy in the presence of chiral solvating agents in order to visualize the presence of individual enantiomers.

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