Non-Covalent Modes of Catalysis

Building upon these concepts, this chapter firstly gives an insight into the modes of action of a selection of non-covalent chiral organocatalysts, employing chiral Brpnsted acid catalysis, chiral Brpnsted base catalysis, and chiral phase-transfer catalysis (PTC). Further sections of this chapter describe two separate case studies that aim to compare and contrast selected covalent and non-covalent strategies for achieving two distinct processes, acyl transfer reactions and asymmetric pericyclic processes. 

As detailed in Sections 42.2 and 42.3, both covalent and non-covalent organocatalytic activation modes have provided efficient strategies to design asymmetric MCRs. A quite recent study by Zhou and list has demonstrated the feasibility of combining asymmetric Bronsted acid catalysis with aminocatalysis to design even more sophisticated reaction sequences toward the synthesis of useful complex molecules. Specifically, they developed a highly enantioselective approach to pharmaceutically relevant 3-substituted cyclohexylamines from 2,6-diketones 223 via an aldolization/dehydration/conjugate reduction/reductive amination domino... 

---