title: Unconventional Bifunctional Lewis-Brønsted Acid Activation Mode in Bicyclic Guanidine-Catalyzed Conjugate Addition Reactions.
abstract: DFT calculations have demonstrated that the unconventional bifunctional Brønsted-Lewis acid activation mode is generally applicable to a range of nucleophilic conjugate additions catalyzed by bicyclic guanidine catalysts. It competes readily with the conventional bifunctional Brønsted acid mode of activation. The optimal pro-nucleophiles for this unconventional bifunctional activation are acidic substrates with low pKa, while the best electrophiles are flexible 1,4-diamide and 1,4-diester conjugated systems.
authors: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. BKCho@ntu.edu.sg.
authors: Bokun
authors: B
authors: Cho
authors: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. chmwmw@nus.edu.sg.
authors: Ming Wah
authors: MW
authors: Wong
mesh_terms: D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods*; D019791:Guanidine / Q000737:chemistry*; D058116:Lewis Acids / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010636:Phenols / Q000737:chemistry; D010797:Phthalimides / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D058116:Lewis Acids; D010636:Phenols; D010797:Phthalimides; D013438:Sulfhydryl Compounds; C042983:thiophenol; D019791:Guanidine
keywords: DFT calculations; activation mode; bifunctional activation; guanidine; mechanism; organocatalysis