Due to the conformational rigidity, the bridged-cyclic chiral phosphorus compounds have been demonstrated to show enantioinducing ability generally superior to conformationally flexible chiral phosphorus compounds as ligands or organocatalysts in catalytic asymmetric reactions. However, investigations into the bridged-cyclic chiral phosphorus compounds are relatively much rarer than the non-bridged-cyclic phosphorus compounds resulting from the paucity of efficient synthetic methods. In order to draw the attention of researchers who are interested in asymmetric synthesis and catalysis to this issue, in this review, we intend to summarize the progress in the synthesis of bridged-cyclic chiral phosphorus compounds and their applications in catalytic asymmetric reactions. We wish this review article could serve as a useful guide and stimulate, to some extent, the interests of asymmetric catalysis scholars to devote to this challenging but greatly important field.

Chiral nickel complexes of bis(oxazoline)s serve as highly active catalysts for an enantioselective reductive alkenylation of N-sulfonyl and N-sulfamoyl aldimines, using readily available alkenyl bromides and triflates as reagents. The new method is readily scalable with low loadings of nickel catalysts, as low as 0.2 mol%. The reaction condition is almost neutral and tolerated polar groups of esters, thioethers, carbamates, heterocyclic pyridine and quinoline, and weakly acidic alcohols. Mechanistically, density functional theory (DFT) calculations reveal that alkenyl transfer to N-sulfonyl imines occurs on nickel catalysts via a classical 1,2-migratory insertion.

Amino acids are typical naturally occurring chiral compounds, whose enantiomeric pairs show distinct biological functions and markedly different application prospects. The precise chiral recognition of amino acid enantiomers is of great significance in diverse fields including life sciences, medical diagnosis, and pharmaceutical development. Over the past decade, chiral fluorescent probes toward amino acids have gained considerable attention for enantiomer recognition. Among these probes, Schiff base chiral fluorescent probes have emerged as a powerful class of sensors for achieving high enantioselective recognition of amino acids, owing to their advantages of facile synthesis, tunable structure, facile functionalization, and excellent photophysical and coordination properties. This review systematically summarizes the research progress of such probes in the enantiomer recognition of different types of amino acids, including acidic, basic, non-polar, and polar amino acids. It focuses on discussing probe design strategies, enantioselective recognition, interaction mechanisms, and application developments. In addition, this paper also highlights and outlines the major challenges existing in this field and the difficult issues that need to be addressed in the future.

Over the past few decades, transition-metal-free chiral Brønsted acid or Lewis acid-catalyzed asymmetric reactions between diazo nucleophiles and imines have emerged as a pivotal strategy for constructing chiral aziridines or β-amino α-diazo derivatives, achieving remarkable synthetic progress. This review summarizes the research advances in asymmetric aza-Darzens reactions and asymmetric Mannich-type reactions of diazo nucleophiles with imines. It encompasses diverse catalytic systems, including chiral boroxinates, chiral dicarboxylic acids, chiral phosphoric acids, chiral N-triflylphosphoramides, and chiral Lewis acids, with an emphasis on the effects of substrate and catalyst on chemoselectivity. Remaining challenges and future perspectives are presented in this review.