Catalytic Asymmetric Synthesis. Группа авторов

Catalytic Asymmetric Synthesis - Группа авторов


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ee (Scheme 2.85). They obtained the X‐ray crystallographic analysis of heterodimer 36 between CPA 6e and acetic acid, and proposed the heterodimeric association of a carboxylic acid with CPA as a new activation principle for organocatalysis. The carboxylic acid plays a dual role in the reaction by both accomplishing the ring‐opening reaction and protecting the catalyst from degradation [172].

Schematic illustration of ring-opening of meso-aziridines.

      Source: Based on [173].

Schematic illustration of kinetic resolution of oxiranes by the transformation of oxirane into thiiranes.

      There are numerous recent reports on the enantioselective construction of axially chiral [175] and planar chiral compounds recently, but those topics will not be discussed here. Please see Chapter 19 [176] for axially chiral compounds and Chapter 20 [177] for planar chiral compounds.

      Chiral Brønsted acid may be employed in combination with metal catalysts. Several kinds of combination are reported such as cooperative catalysis and relay catalysis. We already discussed some asymmetric reactions involving the combination of chiral Brønsted acid and metal catalysts in the previous sections, but we will briefly show several representative reactions in this section.

      Source: [178].

Schematic illustration of dual catalysis system of CPA and Ru complex.

      Source: Based on [179].

      Source: Based on [180].

Schematic illustration of cooperative catalysis with CPA and Fe complex.

      Source: Based on [182].