Asymmetric Synthesis of Nonbiaryl Atropisomers

Next to biaryl and heterobiaryl atropisomers, the third major class of atropisomers is represented by the nonbiaryl analogs. While the molecular architectures are ostensibly less rigid and thus less stable, the right substitution environment yields stable congeners. The recognition of nonbiaryl atropisomers especially in drug development has stimulated efforts to obtain them stereoselectively. This chapter discusses these pursuits, which will be arranged according to diverse subclasses that are most studied: styrenes, amides, diaryl ethers, anilides, ureas, lactams, and diaryl amines. For each class of scaffolds, the generic stability and associated synthetic challenge are discussed, followed by different synthetic strategies developed.