Studies into diastereoselective Dötz benzannulations for the synthesis of axially chiral biaryls

Peptide-Catalyzed Fragment Couplings that Form Axially Chiral Non-C2 -Symmetric Biaryls

We have demonstrated that small, modular, tetrameric peptides featuring the Lewis-basic residue β-dimethylaminoalanine (Dmaa) are capable of atroposelectively coupling naphthols and ester-bearing quinones to yield non-C₂ -symmetric BINOL-type scaffolds with good yields and enantioselectivity. The study culminates in the asymmetric synthesis of backbone-substituted scaffolds similar to 3,3'-disubstituted BINOLs, such as (R)-TRIP, with good (94:6 e.r.) to excellent (>99.9:0.1 e.r.) enantioselectivity after recrystallization, and a diastereoselective net arylation of the minimally modified nonsteroidal anti-inflammatory drug (NSAID) naproxen.

Biaryl synthesis with control of axial chirality

Biaryls have been a persistent focus of interest for chemists since it was recognised, more than 80 years ago, that they can manifest the axial chirality that is inherent in structures consisting of intersecting dissymmetric planes. In recent decades their importance has risen steeply as this structural motif proved spectacularly successful in catalytic synthetic roles and was found to be significant in the context of biological activity. As a consequence, synthetic methods which allowed the construction of biaryls with axial stereocontrol have become highly desirable, and this article traces the development of non-resolution approaches to biaryls with a chosen axial configuration.

Atroposelective Synthesis of Axially Chiral Biaryl Compounds

A rotationally hindered and thus stereogenic biaryl axis is the structurally and stereochemically decisive element of a steadily growing number of natural products, chiral auxiliaries, and catalysts. Thus, it is not surprising that significant advances have been made in the asymmetric synthesis of axially chiral biaryl compounds over the past decade. In addition to the classic approach (direct stereoselective aryl-aryl coupling), innovative concepts have been developed in which the asymmetric information is introduced into a preformed, but achiral-that is, symmetric or configurationally labile-biaryl compound, or in which an aryl--C single bond is stereoselectively transformed into an axis. This Review classifies these strategies according to their underlying concepts and critically evaluates their scope and limitations with reference to selected model reactions and applications. Furthermore, the preconditions required for the existence of axial chirality in biaryl compounds are discussed.