Abstract
Six-membered heterocyclic systems are widely distributed in many natural products
and pharmaceuticals, and the construction of highly functionalized six-membered heterocyclic
compounds is an important topic in modern organic synthesis. Organocatalyzed [3+3]
annulations represents an important method for assembling a substantial variety of
six-membered cycles that contain one or more heteroatoms. This review describes the
development of organocatalyzed [3+3] annulations for the synthesis of six-membered
heterocycles, including organocatalysis using secondary amines, tertiary amines, phosphines,
chiral phosphoric acids and N-heterocyclic carbenes.
1 Introduction
2 Secondary Amine Catalyzed [3+3] Annulations
2.1 Synthesis of Nitrogen Heterocycles
2.2 Synthesis of Oxygen Heterocycles
2.3 Synthesis of Sulfur Heterocycles
3 Tertiary Amine Catalyzed [3+3] Annulations
3.1 Catalysis through Multiple Hydrogen-Bonding Interactions
3.2 Catalysis of Tertiary Amines as Lewis Bases
4 Phosphine-Catalyzed [3+3] Annulations
4.1 Synthesis of Nitrogen Heterocycles
4.2 Synthesis of Oxygen Heterocycles
4.3 Synthesis of Heterocycles Containing Two or More Heteroatoms
5 Chiral Phosphoric Acid Catalyzed [3+3] Annulations
5.1 Synthesis of Nitrogen Heterocycles
5.2 Synthesis of Heterocycles Containing Two or More Heteroatoms
6 N-Heterocyclic Carbene Catalyzed [3+3] Annulations
6.1 Synthesis of Nitrogen Heterocycles
6.2 Synthesis of Oxygen Heterocycles
6.3 Synthesis of Heterocycles Containing Two or More Heteroatoms
7 Conclusion and Outlook
Key words annulations - heterocycles - organocatalysis - amines - phosphines - chiral phosphoric
acids - N-heterocyclic carbenes
