1,1'-Spirobiindane has been one type of privileged skeleton for chiral ligand design, and 1,1'-spirobiindane-based chiral ligands have demonstrated outstanding performance in various asymmetric catalysis. However, the access to enantiopure spirobiindane is quite tedious, which obstructs its practical application. In the present article, a facile enantioselective synthesis of cyclohexyl-fused chiral spirobiindanes has been accomplished, in high yields and excellent stereoselectivities (up to >99% ee), via a sequence of Ir-catalyzed asymmetric hydrogenation of α,α'-bis(arylidene)ketones and TiCl promoted asymmetric spiroannulation of the hydrogenated chiral ketones. The protocol can be performed in one pot and is readily scalable, and has been utilized in a 25 g scale asymmetric synthesis of cyclohexyl-fused spirobiindanediol (1 S,2 S,2' S)-5, in >99% ee and 67% overall yield for four steps without chromatographic purification. Facile derivations of (1 S,2 S,2' S)-5 provided straightforward access to chiral monodentate phosphoramidites 6a-c and a tridentate phosphorus-amidopyridine 11, which were evaluated as chiral ligands in several benchmark enantioselective reactions (hydrogenation, hydroacylation, and [2 + 2] reaction) catalyzed by transition metal (Rh, Au, or Ir). Preliminary results from comparative studies showcased the excellent catalytic performances of these ligands, with a competency essentially equal to the corresponding well-established privileged ligands bearing a regular spirobiindane backbone. X-ray crystallography revealed a close resemblance between the structures of the precatalysts 20 and 21 and their analogues, which ultimately help to rationalize the almost identical stereochemical outcomes of reactions catalyzed by metal complexes of spirobiindane-derived ligands with or without a fused cyclohexyl ring on the backbone. This work is expected to stimulate further applications of this type of readily accessible skeletons in development of chiral ligands and functional molecules.

Alcohols and amines are important in pharmaceutical, perfume, and agrochemical industries. Catalytic asymmetric synthesis is one of the major ways to produce chiral alcohols/amines from prochiral ketones/imines via hydrogenation. Meanwhile, the alcohol/amine dehydrogenation with high hydrogen energy density is paid more and more attention as promising hydrogen‐storage media. In this review, we summarize classifications of mechanisms of ketone/imine hydrogenation and alcohol/amine dehydrogenation catalyzed by transition‐metal (TM) complexes, the H2 activation modes, and the nature of asymmetric ketone/imine hydrogenation (AKH/AIH). This will elaborate our understanding on the nature of the TM‐catalyzed ketone/imine hydrogenation and alcohol/amine dehydrogenation reactions.

The first example of copper-catalyzed decarboxylative atom transfer radical addition of alkynyl carboxylic acids has been developed with a readily available fluoroalkyl halide. This novel protocol has demonstrated a unique difunctionalization of nonterminal alkynes with a broad substrate scope and excellent functional-group tolerance. Mechanistic investigations revealed that the catalytic cycle was initiated by the attack of a difluoroalkyl radical to an in situ generated alkynylcopper species.

Cp*Rh(III)‐catalyzed chelation‐assisted direct C−H bond functionalization of 1‐(2‐pyridyl)‐2‐pyridones with internal alkynes that can be controlled to give three different products in good yields has been realized. Depending on the reaction conditions, solvents and additives, the reaction pathway can be switched between alkenylation, alkenylation/directing group migration and rollover annulation. These reaction manifolds allow divergent access to a variety of valuable C6‐alkenylated 1‐(2‐pyridyl)‐2‐pyridones, (Z)‐6‐(1,2‐diaryl‐2‐(pyridin‐2‐yl)vinyl)pyridin‐2(1H)‐ones and 10H‐pyrido[1,2‐a][1,8]naphthyridin‐10‐ones from the same starting materials. These protocols exhibit excellent regio‐ and stereoselectivity, broad substrate scope, and good tolerance of functional groups. A combination of experimental and computational approaches have been employed to uncover the key mechanistic features of these reactions.