Axial Chirality in Alkylidene‐Cyclic Molecules

Abstract

In celebration of the 25th anniversary of the European Journal of Organic ChemistryAxial chirality is an interesting stereoisomeric phenomenon in organic chemistry and a key structural feature of several organic compounds. Atropisomers such as biaryls, anilides and diaryl ethers are one type of axially chiral compounds, whose axial chirality is resulted from rotationally blocked single bond. Allenes, spiranes and alkylidenecycloalkanes are another type of axially chiral compounds and their axial chirality come from the perpendicular geometry of two pairs of substituents. The axial chirality in atropisomers, allenes and spiranes has been widely investigated and well developed, while the similar chirality in alkylidene-cyclic molecules gained very limited attentions. This concept focuses on summarizing recent advances of axial chirality in alkylidene-cyclic molecules and arouses the research interests to this promising field.

Chiral amino acids: evolution in atroposelective C–H activation

“…5 Given these skeletons’ vast applications and promising abilities, great effort has been devoted in the last few decades to synthesizing axially chiral scaffolds and explore their practical utility in asymmetric catalysis. 6 The common structural features of axially chiral molecules are (i) a non-coplanar arrangement of two pairs of substituents in the parent backbone and (ii) coplanar pairs of substituents that are different from each other. 7 A chiral axis in such frameworks results in the restricted rotation around the single bond, such as in (hetero)biaryls, aryl alkenes, anilides, and diaryl ethers.…”

Enantioselective Construction of Anthracenylidene-Based Axial Chirality by Asymmetric Heck Reaction

“…The increasing prosperity of this type of chirality element over the past few decades has rendered the pursuit of novel skeletons highly intriguing within the synthetic community. The incorporation of the structural features of allenes and spiranes gives rise to a distinct category of axial chirality stereoisomerism observed in alkylidene-cyclic molecules (Scheme a) . The first foray into catalytic asymmetric assembly of this unique structure can be traced back to 1988 when Fiaud and co-workers explored a palladium-catalyzed enantioselective allylic alkylation, albeit with poor enantiocontrol .…”