Published as part of the 50 Years SYNTHESIS – Golden Anniversary Issue
Abstract
This short review provides an overview of 7-azaindoline auxiliaries in asymmetric
catalysis. 7-Azaindoline serves as a useful attachment to carboxylic acids, and the
thus-formed 7-azaindoline amides are amenable to atom-economical C–C bond-forming
reactions with high stereoselectivity. The attachment is used for the sake of gaining
traction in promoting the reaction of interest and can be easily removed after enantioselective
reactions. Both nucleophilic and electrophilic catalyses are realized with broad tolerance
for functional groups, showcasing the usefulness of 7-azaindoline auxiliaries for
practical and streamlined synthesis of a wide range of acyclic chiral building blocks.
1 Introduction
2 7-Azaindoline as a Key Auxiliary
3 7-Azaindoline Amide as a Pronucleophile
3.1 α-Carbon-Substituted 7-Azaindoline Amide
3.2 α-Nitrogen-Substituted 7-Azaindoline Amide
3.3 α-Oxygen-Substituted 7-Azaindoline Amide
3.4 α-Fluorocarbon-Substituted 7-Azaindoline Amide
3.5 α-Halogen-Substituted 7-Azaindoline Amide
3.6 α-Sulfur-Substituted 7-Azaindoline Amide
4 7-Azaindoline Amide as an Electrophile
4.1 Conjugate Addition of Butenolides
4.2 1,3-Dipolar Cycloaddition of Nitrones
5 Transformation of 7-Azaindoline Amide
6 Conclusion
Key words
asymmetric catalysis - C–C bond formation - aldol reaction - Mannich reaction - 7-azaindoline
- cycloaddition