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Comprehensive Summary: Chiral α‐tertiary aminonitriles are valuable synthetic intermediates. They are also found in various structures of biologically active molecules. Therefore, numerous reports of catalytic asymmetric synthesis of chiral α‐aminonitriles continuously emerged during the past few decades. Great strides have been made for the synthesis of chiral α‐aryl and α‐branched alkyl aminonitriles. However, efficient methods for catalytic asymmetric synthesis of chiral α‐linear alkyl aminonitriles remain limited. We herein report a new synthetic approach to chiral α‐tertiary alkyl aminonitriles via catalytic asymmetric isomerization of cyanoketimines. The synthetic value of this method was illustrated by application to a concise catalytic asymmetric synthesis of vildagliptin. [ABSTRACT FROM AUTHOR]

This article discusses a study on the development of a new catalyst for the asymmetric isomerization of β,γ-unsaturated butenolides. The researchers found that chiral betaines derived from precursors were highly efficient catalysts for this reaction. They optimized the reaction conditions and successfully synthesized a range of chiral α,β-butenolides with high enantioselectivity. This research has potential applications in the synthesis of biologically active molecules. The study provides a detailed description of the catalytic cycle and suggests that chiral betaines could be used in various catalytic asymmetric reactions. The supporting information for the study is available online. [Extracted from the article]

In order to extend the e method to general three-dimensional boundary layers, the conservation law of the imaginary parts for the wave parameters with a fixed wave vector is deduced. The compatibility relationship (CR) and the general theory of ray tracing (RT), which have been extensively used in conservative systems, are applied to a general three-dimensional boundary layer belonging to non-conservative systems. Two kinds of e methods, i.e., the eN-CR method and the eN-RT method, are established. Both the two kinds of methods can be used to predict the evolutions of the spanwise wavenumber and the amplitude of the disturbances in general three-dimensional boundary layers. The reliability of the proposed methods is verified and validated by performing a direct numerical simulation (DNS) in a hypersonic general three-dimensional boundary layer over an aircraft model. The results are also compared with those obtained by other e methods, indicating that the proposed methods have great potential applications in improving the transition prediction accuracy in general three-dimensional boundary layers. [ABSTRACT FROM AUTHOR]