Unravelling the Development of Non-Covalent Organocatalysis in India

This review is devoted to underpinning the contributions of Indian researchers towards asymmetric organocatalysis. More specifically, a comprehensive compilation of reactions mediated by a wide range of non-covalent catalysis is illustrated. A detailed overview of vividly catalogued asymmetric organic transformations promoted by hydrogen bonding and Brønsted acid catalysis, alongside an assortment of catalysts is provided. Although asymmetric organocatalysis has etched itself in history, we aim to showcase the scientific metamorphosis of Indian research from baby steps to large strides within this field.

1 Introduction

2 Non-Covalent Catalysis and Its Various Activation Modes

3 Hydrogen-Bonding Catalysis

3.1 Urea- and Thiourea-Derived Organocatalysts

3.1.1 Thiourea-Derived Organocatalysts

3.1.2 Urea-Derived Organocatalysts

3.2 Squaramide-Derived Organocatalysts

3.2.1 Michael Reactions

3.2.2 C-Alkylation Reactions

3.2.3 Mannich Reactions

3.2.4 [3+2] Cycloaddition Reactions

3.3 Cinchona-Alkaloid-Derived Organocatalysts

3.3.1 Michael Reactions

3.3.2 Aldol Reactions

3.3.3 Friedel–Crafts Reactions

3.3.4 Vinylogous Alkylation of 4-Methylcoumarins

3.3.5 C-Sulfenylation Reactions

3.3.6 Peroxyhemiacetalisation of Isochromans

3.3.7 Diels–Alder Reactions

3.3.8 Cycloaddition Reactions

3.3.9 Morita–Baylis–Hilman Reactions

4 Brønsted Acid Derived Organocatalysts

4.1 Chiral Phosphoric Acid Catalysis

4.1.1 Diels–Alder Reactions

4.1.2 Addition of Ketimines

4.1.3 Annulation of Acyclic Enecarbamates

5 Conclusion

Sequential One-Pot Vilsmeier-Haack and Organocatalyzed Mannich Cyclizations to Functionalized Benzoindolizidines and Benzoquinolizidines

The development of new one-pot sequential cyclizations involving a Vilsmeier-Haack reaction followed by an organocatalyzed Mannich reaction is reported. This synthetic strategy gives access to functionalized indolizidines and quinolizidines in one operation from readily synthesized precursors. Yields and diastereoselectivities are good to excellent when formamides are used to trigger the key step, bearing either an electron-rich aryl or a pyrrole as the nucleophilic partner in the first cyclization.