Chiral compounds play a vital role in the fields of medicine and materials science . Among the many approaches to obtain these compounds, asymmetric catalytic synthesis stands out as one of the most efficient and environmentally friendly methods. The ongoing scientific pursuit of chiral compounds has driven the rapid development of new catalysts for asymmetric reactions.

Figure 1. Wide range of applications of Feng’s chiral nitroxides

The Ideal Catalyst—Still a Challenge

In theory, an ideal catalyst should possess the following attributes:

• Easy structural modification

• Low cost

• High stability

• Operational simplicity

• Excellent activity and selectivity

However, no single universal chiral catalyst has yet met all these criteria.

Feng Xiaoming’s Contribution to Chiral Catalysis

Professor Feng Xiaoming of Sichuan University is a renowned chemist in the field of chiral organic synthesis. After two decades of dedicated research into highly efficient and selective chiral catalysts and reactions, his team has successfully designed a class of ligands and catalysts known as N,N′-dioxy compounds (dinitroxide compounds) .

These dinitroxide compounds break traditional expectations by replacing rigid ligand skeletons with a structure that combines rigidity and flexibility , much like a nunchaku . This flexibility allows the reaction environment to be precisely controlled, ensuring that chemical components interact in a highly predictable manner.

Furthermore, the nitrogen-based framework can be fine-tuned to direct various reactions. This enables the production of drug molecules in their most effective single enantiomer form , rather than as racemic mixtures, opening new avenues in asymmetric drug synthesis .

In recognition of his groundbreaking contributions, Feng Xiaoming was awarded the 2018 Future Science Award in Material Science for inventing new catalysts and reaction methods that revolutionized the synthesis of organic, especially pharmaceutical, molecules 1–3.

Roskamp-Feng Reaction: A New Asymmetric Strategy

The Roskamp reaction traditionally involves the Lewis acid-catalyzed reaction of α-acetoxy diazoesters with aldehydes , producing β-keto esters . However, due to the reaction’s rearrangement mechanism, it often yields multiple by-products, primarily from hydrogen migration.

Feng Xiaoming’s team improved the process to achieve asymmetric conversion with high yield and minimal by-products . This optimized version is now known as the Roskamp–Feng reaction (Figure 2), highlighting a major advancement in the field of asymmetric synthesis.

Figure 2:Roskamp-Fengreaction, (using Feng's chiral nitroxide L3 (Cat. NO. 1595287) -Sc(OTf)3 Catalyst, the corresponding selectivity is as high as 98%, and the yield can reach 99%)

Advantages of Chiral Dinitroxide Series Catalysts

1. Broad Applicability:
   Demonstrates wide substrate tolerance, applicable to nearly 20 different asymmetric reaction types , including:

   • Asymmetric haloamination of ketenes

   • α-Amination of ketones
     (See Figure 1 and Table 1)

2. Structural Flexibility:
   A unique balance of rigidity and flexibility allows for high customizability. Substituents can be easily modified to suit specific reaction requirements.

3. Versatile Catalytic Roles:
   These compounds can function either as:

   • Organic small-molecule catalysts, or

   • Ligands in metal-based complex catalysts (e.g., with scandium, copper, nickel, magnesium, lanthanides, etc.)

4. Outstanding Stereoselectivity:
   Provide excellent enantioselectivity and diastereoselectivity across a wide range of reaction types.

5. Commercial Availability:
   J&K Scientific is the exclusive supplier of this series of chiral dinitroxide products. The offerings include:

   • High purity materials

   • Multiple packaging options

   • Reliable inventory availability

Table 1. Some examples of applications of dinitroxide-metal complex catalytic asymmetric synthesis

Feng's Ligand Proline Backbone Product List