The development of novel synthetic strategies to form new chemical entities in a stereoselective manner is an ongoing significant objective in organic and medicinal chemistry. This review analyses the development of new stereoselective approaches to spirocyclic oxindoles with spiro-3- to 8-membered rings. It highlights the importance of these structures for applications in medicinal chemistry, as intermediates or final products in total synthesis and as model compounds for the development of enantioselective catalytic methodologies.

Stereoselective synthesis and applications of spirocyclic oxindoles

Phosphorus-based organocatalysis encompasses several subfields that have undergone rapid growth in recent years. This Outlook gives an overview of its various aspects. In particular, we highlight key advances in three topics: nucleophilic phosphine catalysis, organophosphorus catalysis to bypass phosphine oxide waste, and organophosphorus compound-mediated single electron transfer processes. We briefly summarize five additional topics: chiral phosphoric acid catalysis, phosphine oxide Lewis base catalysis, iminophosphorane super base catalysis, phosphonium salt phase transfer catalysis, and frustrated Lewis pair catalysis. Although it is not catalytic in nature, we also discuss novel discoveries that are emerging in phosphorus(V) ligand coupling. We conclude with some ideas about the future of organophosphorus catalysis.

Phosphorus-Based Catalysis.

The principle of vinylogy states that the electronic effects of a functional group in a molecule are possibly transmitted to a distal position through interposed conjugated multiple bonds. As an em...

New Developments of the Principle of Vinylogy as Applied to π-Extended Enolate-Type Donor Systems

A growing number of organopnictogen redox catalytic methods have emerged-especially within the past 10 years-that leverage the plentiful reversible two-electron redox chemistry within Group 15. The goal of this Perspective is to provide readers the context to understand the dramatic developments in organopnictogen catalysis over the past decade with an eye toward future development. An exposition of the fundamental differences in the atomic structure and bonding of the pnictogens, and thus the molecular electronic structure of organopnictogen compounds, is presented to establish the backdrop against which organopnictogen redox reactivity-and ultimately catalysis-is framed. A deep appreciation of these underlying periodic principles informs an understanding of the differing modes of organopnictogen redox catalysis and evokes the key challenges to the field moving forward. We close by addressing forward-looking directions likely to animate this area in the years to come. What new catalytic manifolds can be developed through creative catalyst and reaction design that take advantage of the intrinsic redox reactivity of the pnictogens to drive new discoveries in catalysis?

Main Group Redox Catalysis of Organopnictogens: Vertical Periodic Trends and Emerging Opportunities in Group 15.

Atropisomeric molecules have found proven applications and promising potentials in chemistry and medicines. The design of N-heterocyclic carbene (NHC)-catalyzed reactions in constructing atropisomerically enriched molecules emerged as an important research topic in recent years. These reactions include kinetic resolutions, asymmetric desymmetrizations, central-to-axial chirality conversions, and cycloadditions. This review evaluates and summarizes the progress on NHC organic catalysis for access to atropisomers, and briefly states our personal perspectives on the future advancement of this direction. NHC catalysis has provided rich and unique reaction modes with numerous success in asymmetric synthesis of central chiral molecules. It is expected that similar success can also be achieved in developing NHC catalysis to prepare atropisomeric molecules, including those not easily accessible with other methods. Readers in the broadly defined community of chemistry shall find this review as a valuable source for information and hopefully inspirations.

Carbene-Catalyzed Asymmetric Construction of Atropisomers.

The last couple of decades have witnessed tremendous development within N-heterocyclic carbene (NHC) organocatalysis. NHCs have been used as powerful organic catalysts in asymmetric synthesis. Although great achievements have been made in asymmetric NHC catalysis, their applications in kinetic resolution (KR), dynamic kinetic resolution (DKR), and desymmetrization processes have been relatively less developed. Moreover, limited activation modes have been involved in these processes. This review provides an overview of the NHC-organocatalyzed KR, DKR, and desymmetrization reactions in the preparation of chiral functional molecules. The aim is to highlight both the importance and elegance of these methods in the construction of challenging chiral compounds and to provide our own perspective on future development in this direction.

N-Heterocyclic Carbene (NHC)-Organocatalyzed Kinetic Resolutions, Dynamic Kinetic Resolutions, and Desymmetrizations.

Tertiary phosphines have been extensively developed as effective organic catalysts/reagents to promote various modern organic transformations in both racemic and enantioselective fashions. However, their applications in radical generation and reactions remain relatively less explored. Phosphine-centered radical species, generated from various tertiary phosphines via phosphine–oxidant charge transfer processes, photoredox catalysis and electrochemical oxidations, can give rise to many unprecedented activation modes and reactions. Single-electron-transfer (SET) reactions associated with tertiary phosphines in particular have recently gained popularity, affording novel and promising synthetic approaches to challenging molecular structures from readily available starting materials upon simple operation. Summarized herein are the historical background and recent breakthroughs in this dynamic field of phosphine-mediated radical organic reactions.

https://pubs.rsc.org/en/content/articlepdf/2020/qo/d0qo00473a

Radical reactions promoted by trivalent tertiary phosphines

https://dr.ntu.edu.sg/bitstream/10356/138269/2/Carbene-catalyzed%20enal%20%ce%b3-carbon%20addition%20to%20%ce%b1-ketophosphonates%20for%20enantioselective%20access%20to%20bioactive%202-pyranylphosphonates.pdf

Carbene-catalyzed enal γ-carbon addition to α-ketophosphonates for enantioselective access to bioactive 2-pyranylphosphonates

A carbene-catalyzed oxidative reaction for the synthesis of dihydropyran-4-carbonitriles bearing all-carbon quaternary centers was developed. The use of a LiCl additive significantly improved both the reaction efficiency and stereo-selectivities, and the carbonitrile products were obtained in good yields and excellent er values.

NHC-catalyzed enantioselective synthesis of dihydropyran-4-carbonitriles bearing all-carbon quaternary centers

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ajoc.201900153

Dingwu Pan

Papers

N-Heterocyclic Carbene (NHC)-Organocatalyzed Kinetic Resolutions, Dynamic Kinetic Resolutions, and Desymmetrizations.

Radical reactions promoted by trivalent tertiary phosphines

Carbene-catalyzed enal γ-carbon addition to α-ketophosphonates for enantioselective access to bioactive 2-pyranylphosphonates

NHC-catalyzed enantioselective synthesis of dihydropyran-4-carbonitriles bearing all-carbon quaternary centers

Efficient Access to 2‐Pyrones via Carbene‐Catalyzed Oxidative [3+3] Reactions between Enals and Nitrogen Ylides