Atropisomerism in Styrene: Synthesis, Stability, and Applications

Abstract

Atropisomeric styrenes are a class of optically active compounds, the chirality of which results from restricted rotation of the C(vinyl)–C(aryl) single bond. In comparison with biaryl atropisomers, the less rigid skeleton of styrenes usually leads them to have lower rotational barriers. Although it has been overlooked for a long time, scientists have paid attention to this class of unique molecules in recent years and have developed many methods for the preparation of optically active atropisomeric styrenes. In this article, we review the development of the concept of atropisomeric styrenes, along with their isolation, asymmetric synthesis, and synthetic applications.1 Introduction2 The Concept of Styrene Atropisomerism3 Early Research: Separation of Optically Active Styrenes4 Synthesis of Optically Active Styrenes5 Stability of the Chirality of Atropisomeric Styrenes6 Outlook

Ir-catalyzed Sequential Asymmetric Allylic Substitution/Olefin Isomerization for the Synthesis of Axially Chiral Compounds

“…其中, 联芳基类轴 手性化合物较为稳定且发展较为成熟 [5] , 而苯乙烯类轴 手性化合物, 由于其烯基和芳基之间的 σ 键旋转能垒较 低, 轴手性相对不稳定. 因此, 高效立体选择性构建苯 乙烯类轴手性化合物一直是不对称合成领域的挑战 [6] (图 1b).…”

Rhodium-catalyzed atroposelective access to trisubstituted olefinsviaC–H bond olefination of diverse arenes

“…1 As a result, catalytic asymmetric construction of axially chiral scaffolds has attracted great attention in the past several decades. 2–6 Previous studies have been primarily devoted to synthesis of binaphthalene-based atropisomers and other related 6–6 biaryl systems. 3 However, the investigation of axially chiral molecules with a relatively lower rotational energy barrier lags behind, such as five-membered biaryls, 4 chiral amides, 5 and axially chiral olefins.…”

Atherton–Todd Reaction-Guided Enantioselective Synthesis of Axially Chiral Olefins via Bifunctional Phosphonium Salt-Regulating Ketone-Enol Tautomerism

“…Of note, their enantioselective synthesis in a catalytic manner is desirable but more challenging. The key challenges are probably due to the difficult control of E / Z selectivity of the olefin structure and the low rotational barrier of the flexible axis which could result in the weak configurational stability (Figure a), certainly together with the sporadic appearance of efficient chiral catalytic systems to meet these inherent issues . Until recently, as the installation of an alkene into chiral molecules would be beneficial to improving their bioactivities and synthetic applications, axially chiral olefins were flourished gradually; and to this end several preparation approaches, i.e., aryl–alkenyl cross-coupling, C/N–H functionalization of alkenes, conjugate addition of alkynes, and kinetic resolution of intrinsic alkenyl axes, have emerged for the facile assembly of axially chiral acyclic or cyclic aryl–alkene scaffolds (Figure b).…”