Hydrogen‐Bond‐Enabled Dynamic Kinetic Resolution of Axially Chiral Amides Mediated by a Chiral Counterion

Non‐biaryl atropisomers are valuable in medicine, materials, and catalysis, but their enantioselective synthesis remains a challenge. Herein, a counterion‐mediated O‐alkylation method for the generation of atropisomeric amides with an er up to 99:1 is outlined. This dynamic kinetic resolution is enabled by the observation that the rate of racemization of atropisomeric naphthamides is significantly increased by the presence of an intramolecular O?H???NCO hydrogen bond. Upon O‐alkylation of the H‐bond donor, the barrier to rotation is significantly increased. Quantum calculations demonstrate that the intramolecular H‐bond reduces the rotational barrier about the aryl–amide bond, stabilizing the planar transition state for racemization by approximately 40 kJ mol^?1, thereby facilitating the observed dynamic kinetic resolution.     

A Strategy for Synthesizing Axially Chiral Naphthyl‐Indoles: Catalytic Asymmetric Addition Reactions of Racemic Substrates

A new strategy for enantioselective synthesis of axially chiral naphthyl‐indoles has been established through catalytic asymmetric addition reactions of racemic naphthyl‐indoles with bulky electrophiles. Under chiral phosphoric acid catalysis, azodicarboxylates and o‐hydroxybenzyl alcohols served as bulky but reactive electrophiles that were attacked by C2‐unsubstituted naphthyl‐indoles, which underwent a dynamic kinetic resolution to afford two series of axially chiral naphthyl‐indoles in good yields (up to 98 %) and high enantioselectivities (up to 98:2 er).     

Arylation of Axially Chiral Phosphorothioate Salts by Dinuclear PdI Catalysis

S‐aryl phosphorothioates are privileged motifs in pharmaceuticals, agrochemicals, and catalysts; yet, the challenge of devising a straightforward synthetic route to enantioenriched S‐aryl phosphorothioates has remained unsolved to date. We demonstrate herein the first direct C?SP(=O)(OR′)(OR′′) coupling of diverse and chiral phosphorothioate salts with aryl iodides, enabled by an air‐ and moisture‐stable Pd^I dimer. Our mechanistic and computational data suggest distinct dinuclear Pd^I catalysis to be operative, which allows for operationally simple couplings with broad scope and full retention of stereochemistry.     

古斯—汉欣位移的发现与发展

目前古斯-汉欣位移泛指有限束宽光束在界面处反射或透射时,在入射平面内会出现偏离几何光学预言的一小段横向移动量。古斯—汉欣位移的研究可追溯至牛顿时代,但直到1947年才在实验上发现了该位移,此后人们开始对其逐步深入研究。作为一种基本的物理现象,它已延伸到声学、量子力学和物质波等领域。文章作者结合自身研究经历与认识,从古斯—汉欣位移的发现、理论解释及最新的研究进展等方面对其进行介绍。     

Internal Nucleophilic Catalyst Mediated Cyclisation/Ring Expansion Cascades for the Synthesis of Medium‐Sized Lactones and Lactams

A strategy for the synthesis of medium‐sized lactones and lactams from linear precursors is described in which an amine acts as an internal nucleophilic catalyst to facilitate a novel cyclisation/ring expansion cascade sequence. This method obviates the need for the high‐dilution conditions usually associated with medium‐ring cyclisation protocols, as the reactions operate exclusively via kinetically favourable “normal”‐sized cyclic transition states. This same feature also enables biaryl‐containing medium‐sized rings to be prepared with complete atroposelectivity by point‐to‐axial chirality transfer.