Runjiang Song

Bio: Runjiang Song is an academic researcher from Nanyang Technological University. The author has contributed to research in topics: Medicine & Chemistry. The author has an hindex of 7, co-authored 11 publications receiving 141 citations.

Carbene-Catalyzed Asymmetric Construction of Atropisomers.

Abstract: Atropisomeric molecules have found proven applications and promising potentials in chemistry and medicines. The design of N-heterocyclic carbene (NHC)-catalyzed reactions in constructing atropisomerically enriched molecules emerged as an important research topic in recent years. These reactions include kinetic resolutions, asymmetric desymmetrizations, central-to-axial chirality conversions, and cycloadditions. This review evaluates and summarizes the progress on NHC organic catalysis for access to atropisomers, and briefly states our personal perspectives on the future advancement of this direction. NHC catalysis has provided rich and unique reaction modes with numerous success in asymmetric synthesis of central chiral molecules. It is expected that similar success can also be achieved in developing NHC catalysis to prepare atropisomeric molecules, including those not easily accessible with other methods. Readers in the broadly defined community of chemistry shall find this review as a valuable source for information and hopefully inspirations.

N-Heterocyclic Carbene Catalyzed Radical Coupling of Aldehydes with Redox-Active Esters.

Abstract: N-Heterocyclic carbene catalyzed radical reactions are challenging and underdeveloped. In a recent study, Ohmiya, Nagao and co-workers found that aldehyde carbonyl carbon centers can be coupled with alkyl radicals under NHC catalysis. An elegant aspect of this study is the use of a redox-active carboxylic ester that behaves as an single-electron oxidant to convert the Breslow intermediate into a radical adduct and concurrently release an alkyl radical intermediate as a reaction partner.

Gold and Carbene Relay Catalytic Enantioselective Cycloisomerization/Cyclization Reactions of Ynamides and Enals

Abstract: The combined use of gold as transition metal catalyst and N-heterocyclic carbene (NHC) as organic catalyst in the same solution for relay catalytic reactions was disclosed. The ynamide substrate was activated by gold catalyst to form unsaturated ketimine intermediate that subsequently reacted with the enals (via azolium enolate intermediate generated with NHC) effectively to form bicyclic lactam products with excellent diastereo- and enantio-selectivities. The gold and NHC coordination and dissociation can be dynamic and tunable events, and thus allow the co-existence of both active metal and carbene organic catalysts in appreciable concentrations, for the dual catalytic reaction to proceed.

NHC-catalyzed covalent activation of heteroatoms for enantioselective reactions

Abstract: Covalent activation of heteroatoms enabled by N-heterocyclic carbene (NHC) organic catalysts for enantioselective reactions is evaluated and summarized in this review. To date, sulfur, oxygen, and nitrogen atoms can be activated in this manner to react with another substrate to construct chiral carbon–heteroatom bonds with high optical enantioselectivities. The activation starts with addition of an NHC catalyst to the carbonyl moiety (aldehyde or imine) of substrates that contain heteroatoms. The key in this approach is the formation of intermediates covalently bound to the NHC catalyst, in which the heteroatom of the substrate is activated as a nucleophilic reactive site.

Recent advances in the application of Diels-Alder reactions involving o-quinodimethanes, aza-o-quinone methides and o-quinone methides in natural product total synthesis.

Abstract: In recent decades, transient and highly reactive ortho-quinodimethanes (o-QDMs), ortho-quinone methides (o-QMs) and aza-ortho-quinone methides (aza-o-QMs) have attracted much attention and have been extensively studied and applied in organic synthesis, especially natural product total synthesis. This review summarizes recent advances in Diels–Alder reactions involving in situ-generated o-QDMs, o-QMs and aza-o-QMs, highlighting the power and potential of this strategy in organic synthesis and natural product total synthesis. An overview of the methods for generating these intermediates is also available.

N-Heterocyclic Carbene-Based Catalysis Enabling Cross-Coupling Reactions

Abstract: N-Heterocyclic carbene (NHC) organocatalysis to promote so-called umpolung reactions has emerged as a powerful tool for modern organic synthesis. NHC-bound nucleophiles known as Breslow intermediat...

Recent advances in N-heterocyclic carbene-based radical catalysis

Abstract: In nature, a number of enzymes use thiamine diphosphate as a coenzyme to catalyze the pyruvate decarboxylation. The resultant enamine, a so-called "Breslow intermediate," is known to perform single electron transfer to various electron acceptors. Inspired by this enzymatic catalysis, N-heterocyclic carbene (NHC)-catalyzed radical reactions have been developed. This minireview highlights the recent progress and developments in NHC-based radical catalysis. This minireview is categorized according to the reaction types; oxidation type reaction and carbon-carbon bond formation through single electron transfer/radical-radical coupling.

N-Heterocyclic Carbene-Catalyzed Radical Relay Enabling Vicinal Alkylacylation of Alkenes.

Abstract: The N-heterocyclic carbene-catalyzed radical relay enables the vicinal alkylacylation of styrenes, acrylates and acrylonitrile using aldehydes and tertiary alkyl carboxylic acid-derived redox-activ...