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A Pd‐catalyzed synthesis of 5‐iminopyrrolones from propiolamides was developed, which featured wide substrate scope and good yields. This efficient conversion involved a tandem hydrocyanation, E to Z isomerization of alkenes, and nitrile/amide cyclization. Control experiments show the intermediacy of β‐cyanation products, and the Z‐isomers was efficiently converted to the target products by Pd/L2 catalysis only after the cyanation reagent was completely consumed. [ABSTRACT FROM AUTHOR]

Daphenylline, a structurally unique triterpenoid Daphniphyllum alkaloid, has attracted considerable attention from the synthetic community since its isolation. Herein, we delineate an enantioselective total synthesis of (−)‐daphenylline, which is based on a gold‐catalyzed dearomatization reaction of β‐methoxynaphthalene. Other features include installation of the initial chiral stereocenter via an enantioselective rhodium‐catalyzed hydrogenation of an alkylidene‐indane derivative; construction of the other vital stereocenter by organocatalytic asymmetric Mukaiyama–Michael reaction of a structurally complex benzofused cyclohexanone; and a tandem reductive amination/amidation double cyclization reaction to assemble the distinctive azapolycyclic cage‐like architecture. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The construction of acyclic quaternary carbon stereocenters, which are ubiquitous in many bioactive compounds, pharmaceuticals and natural products, has been a long persuit in synthetic organic chemistry. Among numerous methods, enantioselective nickel‐catalysis has attracted incremental attention in recent years. This review summarizes the recent development in the asymmetric strategies, research progress, mechanistic investigations for the generation of acyclic quaternary carbon stereocenters via enantioselective nickel catalysis. Key Scientists: In 2006, the Zhou group and RajanBabu group realized the nickel‐catalyzed enantioselective hydrovinylation of α‐substituted styrenes and ethylene to construct acyclic quaternary carbon stereocenters (QCSs) by using spiro‐ and binaphthyl phosphoramidite ligands, respectively. In 2016, Watson developed a nickel‐catalyzed Suzuki‐Miyaura arylation to generate acyclic QCSs via chirality transfer reaction. In 2017, the Feng and the Fu group developed nickel‐catalyzed enantioselective conjugated/Michael additions to build acyclic QCSs, respectively. In 2020, the Fang group made the first success in the construction of QCSs by nickel‐catalyzed hydrocyanation of alkenes and allenes. In 2021, Gregory C. Fu and co‐workers disclosed a nickel‐catalyzed enantioselective α‐functionalization of carbonyl compounds that could form acyclic QCSs. At the same time, the Shi group constructed chiral acyclic QCSs via nickel‐catalyzed functionalization of alkenes. In 2023, Kleij and co‐workers applied a new strategy for Ni‐catalyzed regio‐ and enantioselective homoallylic coupling to construct acyclic QCSs. In the same year, Tao and co‐workers demonstrated a novel strategy that is dinickel‐catalyzed enantioselective α‐alkylation of carbonyl compounds with alkyl iodides. [ABSTRACT FROM AUTHOR]

Metal‐hydride‐catalyzed migratory functionalization of alkenes witnessed extensive development in the past few years. However, the asymmetric version of this reaction has remained largely underdeveloped owing to the difficulty in simultaneous control of both regio‐ and stereoselectivity. In addition, exploring the wider alkene substrate scope to enable more synthetically valuable applications represents another challenge in this field. In this context, a nickel‐catalyzed asymmetric hydrocyanation of internal alkenes involving a chain‐walking process is demonstrated. The reaction exhibits excellent regio‐ and enantioselectivity, proceeds under mild reaction conditions, and delivers benzylic nitriles in high yields. Even α,ω‐diaryl internal alkenes, which are known to be one of the most challenging substrates of this type, could be successfully converted to the desired products with good regio‐ and stereoselectivity by modifying the electronic and steric effects. Theoretical calculations suggest that the η3‐benzyl coordination mode and the aryl substituent (3,5‐(OMe)2C6H3) on the diphosphite ligand are both key factors in regulating regio‐ and enantioselectivity. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The construction of acyclic quaternary carbon stereocenters, which are ubiquitous in many bioactive compounds, pharmaceuticals and natural products, has been a long persuit in synthetic organic chemistry. Among numerous methods, enantioselective nickel‐catalysis has attracted incremental attention in recent years. This review summarizes the recent development in the asymmetric strategies, research progress, mechanistic investigations for the generation of acyclic quaternary carbon stereocenters via enantioselective nickel catalysis. Key Scientists: In 2006, the Zhou group and RajanBabu group realized the nickel‐catalyzed enantioselective hydrovinylation of α‐substituted styrenes and ethylene to construct acyclic quaternary carbon stereocenters (QCSs) by using spiro‐ and binaphthyl phosphoramidite ligands, respectively. In 2016, Watson developed a nickel‐catalyzed Suzuki‐Miyaura arylation to generate acyclic QCSs via chirality transfer reaction. In 2017, the Feng and the Fu group developed nickel‐catalyzed enantioselective conjugated/Michael additions to build acyclic QCSs, respectively. In 2020, the Fang group made the first success in the construction of QCSs by nickel‐catalyzed hydrocyanation of alkenes and allenes. In 2021, Gregory C. Fu and co‐workers disclosed a nickel‐catalyzed enantioselective α‐functionalization of carbonyl compounds that could form acyclic QCSs. At the same time, the Shi group constructed chiral acyclic QCSs via nickel‐catalyzed functionalization of alkenes. In 2023, Kleij and co‐workers applied a new strategy for Ni‐catalyzed regio‐ and enantioselective homoallylic coupling to construct acyclic QCSs. In the same year, Tao and co‐workers demonstrated a novel strategy that is dinickel‐catalyzed enantioselective α‐alkylation of carbonyl compounds with alkyl iodides. [ABSTRACT FROM AUTHOR]

In industry, the two important nitrile starting materials, adiponitrile and 2-methylglutaronitrile, are primarily manufactured through the well-known DuPont process, which consists of a tandem sequence including first hydrocyanation, isomerization and second hydrocyanation. However, this mature process has the intrinsic defects of step efficiency and regioselectivity. Herein, we report a nickel-catalyzed divergent, one-step double hydrocyanation of 1,3-butadiene to produce either adiponitrile or 2-methylglutaronitrile in high regioselectivity. The key to this success lies in the highly tunable binding pockets of the bidentate phosphite ligands, which creates a geometrically defined coordination space around the nickel center. The first hydrocyanation that produces either the linear or branched alkenyl nitrile was identified as the selectivity-determining step. Organometallic studies confirm the formation of well-defined diphosphite nickel diene complexes in solution, and the role of ligands in dictating regioselectivity was further rationalized by DFT computations. This result provides the first example of a highly selective nickel-catalyzed synthesis of adiponitrile and 2-methylglutaronitrile from butadiene, and it also represents a high-level of catalyst-controlled regioselectivity via the fine-tuning of ligand pocket geometry., (© 2024 Wiley-VCH GmbH.)