(3 + 2) Cycloadditions by Nucleophilic Organocatalysis
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Abstract Enantioselective organocatalysis by using N‐heterocyclic carbenes (NHCs) has emerged as a powerful strategy for the construction of complex chiral molecules. Recently, remarkable advances have been made in enantioselective NHC‐catalyzed reactions that involve diverse activation intermediates, such as Breslow intermediates, homoenolate intermediates, α,β‐unsaturated acylazoliums, azolium enolates, and azolium dienolates, which are generated by the nucleophilic addition of NHCs to aldehydes. Furthermore, NHC‐catalyzed reactions that proceed through non‐covalent bonding interactions have also been developed.
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