Abstract
The history of proline sulfonamides for use in catalyzing highly
enantioselective and diastereoselective C-C bond forming reactions
is described. Highlighted is the development of N -(p -dodecylphenylsulfonyl)-2-pyrrolidinecarboxamide
(‘Hua Cat’) and N -(carboxy-p- dodecylphenylsulfonyl)-2-pyrrolidinecarboxamide (‘Hua
Cat-II’) by Yang and Carter. Specific reactions covered
include the aldol reaction, Mannich reaction, formal aza-Diels-Alder reaction,
tandem Michael/Mannich reaction and Yamada-Otani reaction.
The ability of proline aryl sulfonamides to construct all-carbon
quaternary stereocenters in high enantioselectivity and diastereoselectivity
is a notable feature of the reported work. The practicality of this
chemistry for large scale and industrial applications is also included.
Finally, a discussion of the future directions of proline sulfonamide
organocatalysis is provided.
1 Introduction
2 Proline Sulfonamides
2.1 Synthesis of First Proline Sulfonamides
2.2 Early Proline Sulfonamide Organocatalysis
3 Hua Cat
3.1 Discovery of Hua Cat
3.2 Intramolecular Michael Additions
3.3 Aldol Reactions
3.4 Mannich Reactions
3.5 Aza-Diels-Alder Reactions
3.6 Quaternary Center Formation
3.7 Stereogenic, All-Carbon Quaternary Center Formation in Bicyclic
Scaffolds
3.8 Yamada-Otani Reaction and Hua Cat-II
4 Future Directions
5 Conclusion
Key words
asymmetric catalysis - amino acids - enantioselectivity - sulfonamides - solvent effects - aldol reaction - multicomponent reaction - Michael addition - phase-transfer
catalysis