Synthesis 2022; 54(19): 4129-4166
DOI: 10.1055/a-1856-5688
review

Recent Advances in Enantioselective Organocatalytic Reactions Enabled by N-Heterocyclic Carbenes (NHCs) Containing Triazolium Motifs

a   Department of Industrial and Engineering Chemistry, Institute of Chemical Technology, IndianOil Odisha Campus, Kharagpur Extension Centre, Mouza, Samantpuri, Bhubaneswar-751013, Odisha, India
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a   Department of Industrial and Engineering Chemistry, Institute of Chemical Technology, IndianOil Odisha Campus, Kharagpur Extension Centre, Mouza, Samantpuri, Bhubaneswar-751013, Odisha, India
,
b   Department of Chemistry, National Institute of Technology Puducherry, Karaikal-609609, Union Territory Puducherry, India
,
a   Department of Industrial and Engineering Chemistry, Institute of Chemical Technology, IndianOil Odisha Campus, Kharagpur Extension Centre, Mouza, Samantpuri, Bhubaneswar-751013, Odisha, India
› Author Affiliations
The authors acknowledge the Institute of Chemical Technology, Indian OilOdisha Campus (ICT-IOC), Bhubaneswar for providing necessary support. R.D. thanks the Department of Science and Technology, Science and Engineering Research Board (DST-SERB) for a Ramanujan Fellowship (SB/S2/RJN-075/2016), a Core Research Grant (CRG/2018/000782) and ICT-IOC for a start-up grant. V.D. thanks DST-SERB for a Ramanujan Fellowship (RJF/2020/000038) and the National Institute of Technology Puducherry, Karaikal, India for providing necessary research work support.


Dedicated to Prof. Paul Knochel

Abstract

N-Heterocyclic carbenes (NHCs) containing triazolium motifs have emerged as a powerful tool in organocatalysis. Recently, various NHC-catalyst-mediated organic transformations have been developed. This review aims to compile the current state of knowledge on enantioselective NHC-triazolium-catalyzed named reactions as well as introduce newly developed catalytic methods. Furthermore, this review article framework provides an excellent opportunity to highlight some of the unique applications of these catalytic procedures in the synthesis of natural products and biologically active compounds, notably the extensive processes for the preparation of substituted chiral alcohols and their derivatives. This review also provides an overview of the synthesis of chiral NHC-triazolium-catalyst libraries and their applications in catalytic enantioselective reactions.

1 Introduction

2 Synthesis of N‑Heterocyclic Carbenes Containing Triazolium Motifs

2.1 Pyrrolidine-Based Triazoliums NHCs: Px

2.2 Morpholine-Based Triazoliums NHCs: Mx

2.3 Aminoindane-Based Triazoliums NHCs: AMx

2.4 Oxazolidine-Based Heteroazoliums NHCs: Ox

2.5. Acyclic Triazoliums NHCs: Ax

3 Enantioselective Organocatalytic Reactions

3.1 Enantioselective Benzoin Reactions

3.1.1 Aldehyde–Aldehyde Homo-Benzoin Reactions

3.1.2 Aldehyde–Aldehyde Cross-Benzoin Reactions

3.1.3 Aldehyde–Ketone Cross-Benzoin Reactions

3.1.4 Aldehyde–Imine Cross-Benzoin Reactions

3.1.5 Aza-Benzoin Reactions

3.2 Enantioselective Stetter Reactions

3.2.1 Intramolecular Stetter Reactions

3.2.2 Intermolecular Stetter Reactions

3.3 Enantioselective Diels–Alder Reactions

3.4 Enantioselective Michael Additions

3.5 Enantioselective Rauhut–Currier Reactions

3.6 Enantioselective Cycloadditions

3.7 Enantioselective Michael–Stetter Cascade Reactions

3.8 Enantioselective Annulation Reactions

3.9 Synthesis of Spiro Compounds

3.10 Heterocycle Synthesis

3.11 Carbocycle Synthesis

3.12 Asymmetric Steglich Rearrangement Reactions

3.13 NHC-Mediated Asymmetric Acylation/Hydroacylation Reactions

3.14 Enantioselective α-Fluorination of Aliphatic Aldehydes

3.15 Functionalization of Carboxylic Anhydrides by NHC Catalysis

3.16 Asymmetric β-Boration of Acyclic Enones

3.17 Synthesis of Tropane Derivatives via Organocatalysis

3.18 Dynamic Kinetic Resolution of Pyranones via NHC Catalysis

3.19 Enantioselective Umpolung Reactions

3.20 Enantioselective Esterification of Ketenes

3.21 Asymmetric Synthesis of trans-γ-Lactams

3.22 Oxy-Cope Rearrangements

3.23 Claisen Rearrangements

3.24 Enantioselective Synthesis of Complex Heterocycles

3.25 Atroposelective Synthesis of N-Aryl Succinimides

3.26 Asymmetric α-Fluorination via Cascade Reactions

4 Conclusion



Publication History

Received: 31 March 2022

Accepted after revision: 19 May 2022

Accepted Manuscript online:
19 May 2022

Article published online:
03 August 2022

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