Robby Vroemans

Publication date: 1 July 2026

Source: Coordination Chemistry Reviews, Volume 558

Author(s): Fan Yang, Xinyu Zhang, Christophe M. Thomas, Régis M. Gauvin

Synthesis
DOI: 10.1055/a-2822-8780

Levulinic acid (LA) is a key biomass-derived platform molecule that provides access to a wide range of value-added chemicals through selective functional-group manipulation. Although transition-metal catalysis has traditionally dominated LA upgrading, recent years have witnessed rapid progress in transition-metal-free synthetic strategies based on main-group reagents, Brønsted (or Lewis) acids and bases, and organocatalytic activation modes. This Short Review summarizes recent advances in the metal-free synthesis and transformation of LA, with a particular focus on reaction design and mechanistic features relevant to organic synthesis. Key topics include chemoselective reduction to γ-valerolactone and related oxygenates, pH-controlled oxidative C–C bond cleavage to functional organic acids, acid-mediated condensation reactions toward polymer-relevant monomers, and metal-free amination and cyclization pathways affording nitrogen-containing heterocycles. By organizing these transformations according to reaction class and selectivity control, this review highlights how foundational organic reactivity can be leveraged to achieve efficient and sustainable valorization of LA without reliance on transition metals.
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Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany

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Synlett
DOI: 10.1055/a-2785-2408

We report on the development of a catalytic atroposelective aza-Grob fragmentation of α-keto oxime esters—the first of its kind catalytic asymmetric version of this classical reaction. By leveraging torsional strain and multiple hydrogen-bonding activation, a catalytic asymmetric addition, followed by a stereospecific carbon–carbon cleavage reaction was developed, delivering axially chiral biarylnitriles in high yield and enantioselectivity. In this Synpact article, we present the conceptual framework of the catalytic asymmetric aza-Grob fragmentation and highlight the key structural features that enable atroposelective C–C bond scission.
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Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany

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The photoredox-catalyzed chlorosulfonylation of gem-difluoroalkenes with sulfonyl chlorides is achieved under mild conditions. The reaction enables efficient synthesis of the α,α-difluoromethyl-β-chlorosulfonyl skeleton and demonstrates excellent functional group tolerance. This method provides novel insights into the construction of functional fluorinated frameworks relevant to medicinal chemistry.

A visible-light-catalyzed chlorosulfonylation reaction of gem-difluoroalkenes has been successfully developed using sulfonyl chloride as both the sulfonyl group and chlorine source. The reaction proceeds under mild, additive-free conditions, generating α,α-difluoromethyl-β-chlorosulfones with excellent regioselectivity and broad substrate scope. The β-chlorosulfone product serves as versatile intermediate, readily converting into valuable derivatives such as β-azido sulfone. This method provides rapid access to functional fluorinated scaffolds relevant to medicinal chemistry.

Publication date: June 2026

Source: Fire Safety Journal, Volume 161

Author(s): Serge Bourbigot

Catalysis Rules! The year 2025 marks the 20^th anniversary of diarylprolinol silyl ethers in asymmetric organocatalysis. During the first decade after their discovery, these catalysts have been established as one of the most versatile tools in aminocatalysis. Although now considered mature, recent years have witnessed renewed innovation. We outlined these developments, demonstrating that this remains a rapidly evolving field.

ABSTRACT

A new chapter starts now. Since its discovery in 2005, the diarylprolinol silyl ether catalytic concept has emerged as a general and reliable aminocatalytic tool for the synthesis of enantioenriched molecules. Recently its combination with emerging technologies, as well as its application in more complex molecular systems has opened new avenues for novel enantioenriched scaffolds. In this review, we will highlight these recent developments, unfolding five primary categories that define new horizons in the use of diarylprolinol silyl ethers: Photochemical-, electrochemical-, dual-catalytic transformations, higher-order cycloadditions and applications in total synthesis of complex natural products.

Site-selective C_α–H radical azidation of alkyl boronates is challenging due to significant regio- and chemo-selectivity issues. Herein, an iron-catalyzed C(sp³)–H azidation of secondary B(MIDA) boronates, leveraging σ(B–N) → p(C) hyperconjugation for α-radical stabilization, is reported, providing α-azidoboronates as valuable building blocks.

Comprehensive Summary

α-Azidoboronates, integrating both azido and boryl groups, are versatile intermediates for accessing α-aminoborons, α-triazolylborons, and bioorthogonal ligation handles. However, existing syntheses rely primarily on nucleophilic substitution of pre-functionalized α-haloboronates, which require multistep cryogenic Matteson homologation and involve unstable intermediates as well as hazardous azide reagents. Direct Cα–H azidation of alkyl boronates offers an appealing alternative but remains challenging due to competing radical addition to the sp²-boron center, leading to deborylation. Motivated by the unique stereoelectronic properties of B(MIDA) groups, which can stabilize α-radicals and promote boron-retentive transformations, we envisioned that selective radical C–H azidation of secondary B(MIDA)s could be feasible. Herein, we establish an iron-catalyzed protocol enabling efficient and site-selective Cα–H azidation of secondary MIDA boronates, leveraging σ(B–N) → p(C) hyperconjugation for α-radical stabilization. The protocol furnishes a broad range of α-azidoboronates in a single step. Preliminary studies further demonstrate their compatibility with click chemistry, underscoring their potential utility in functional molecule construction and bioorthogonal applications.

Synthesis
DOI: 10.1055/a-2764-1105

Over the past decade, planar chiral sulfur-containing [2.2]paracyclophanes have attracted increasing attention. This review offers a comprehensive overview of the strategies developed to access these appealing derivatives, along with their diverse applications in fields ranging from catalysis to materials science. The discussion is organized according to the type and position of the sulfur functional group within the [2.2]paracyclophane framework.
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Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany

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