Synlett

We describe effective development of the highly diastereoselective synthesis of double helical tetraamine 2-H2-C2 and propose a mechanism for its formation. The resolution of 2-H2-C2 is facilitated by a high racemization barrier of 43 kcal mol–1 and it is implemented via either a chiral auxiliary or preparative supercritical fluid chromatography. This enables preparation of the first high-spin neutral diradical, with spin density delocalized within an enantiomeric double helical π-system. The presence of two effective 3-electron C–N bonds in the diradical leads to: (1) the triplet (S = 1) high-spin ground state with a singlet-triplet energy gap of 0.4 kcal mol–1 and (2) the long half-life of up to 6 days in 2-MeTHF at room temperature. The diradical possesses a racemization barrier of at least 26 kcal mol–1 in 2-MeTHF at 293 K and chiroptical properties, with an absorption anisotropy factor |g| ≈ 0.005 at 548 nm. These unique magnetic and optical properties of our diradical form the basis for the development of next-generation spintronic devices.1 Introduction2 Synthesis and Resolution of the C
2-Symmetric Double Helical Tetraamine 2-H2-C
2
3 Synthesis and Characterization of Neutral High-Spin Aminyl Diradical 22•
-C
2
4 Conclusion

The development of an effective catalytic system for the dehydrogenative coupling of hydrosilanes with alcohols remains an ongoing challenge, particularly for alcohol protection applications. In this study, we report the development and optimization of a highly efficient gold catalyst supported on fibrillated cellulose modified with citric acid. The catalyst exhibited remarkable catalytic activity under mild conditions with 0.01–0.05 mol% of Au loading, facilitating the formation of silyl ethers with excellent yield. Notably, our catalytic system overcomes the need for excess alcohol, typically required in such reactions, making it highly practical for alcohol protection applications. This work represents a significant advancement in the field of dehydrosilylation catalysis, offering a sustainable, efficient, and environmentally friendly approach for the synthesis of functional silanol-based materials and alcohol protection applications. The scope of substrates and the utility of the catalyst have been thoroughly studied.

Vinylbenziodoxolones (VBXs) are important electrophilic alkene synthons. However, the synthesis of cis-thiophenol-VBX reagents from ethynylbenziodoxolones (EBXs) and thiophenols remains challenging. Herein, we explore an efficient method for the synthesis of cis-thiophenol-VBXs in excellent yield with excellent regio- and stereoselectivities from EBXs and thiophenols under temperature-controlled conditions.

In this investigation, N-substituted phosphinecarboxamides were produced through the reaction of [TBA][P(SiCl3)2] with isonitriles. This method capitalizes on the flexibility of isonitriles as a source of both nitrogen and carbonyl groups, offering a novel route to the generation of PH2-type compounds. This approach is characterized by rapid reaction times, simple procedural requirements, compatibility with a diverse array of substrates, and the conversion of [TBA][P(SiCl3)2] into organic phosphorus compounds. Additionally, we systematically studied the reaction mechanism of isonitrile with [TBA][P(SiCl3)2] through controlled experiments and density functional theory (DFT) calculations.

Allylic C(sp
3)–H functionalized architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials, but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry. Accordingly, various strategies to access allylic functionalized alkenes in a stereoselective manner have been developed. However, chemo-, regio- and stereoselective intermolecular asymmetric allylic functionalization (AAF) of unreactive acyclic alkene (UAA) from readily available materials, representing a highly atom- and step-economic approach toward the generation of structural complexity, remains elusive and challenging. Herein, we review all intermolecular asymmetric catalyzed methods, with emphasis on the construction of chiral allylic units by activation of allylic C–H bonds of UAAs. Our analysis serves to document the considerable and rapid progress within the field, while also highlighting the limitations of current methods.1 Introduction2 Asymmetric Allylic Oxygenation3 Asymmetric Allylic Amination4 Asymmetric Allylic Carbonization5 Asymmetric Allylic Sulfuration6 Conclusion and Outlook

Chiral L2/Z*-type ligands featuring a bisoxazoline framework have been successfully synthesized and applied in asymmetric allylic alkylation. These ligands, designed based on an oxazoline skeleton and derived from chiral amino acid derivatives, incorporate antimony and bismuth as Z-type ligands. Ligands with bulky, electron-withdrawing groups on antimony and bismuth showed enhanced catalytic performance. This research highlights the potential of these novel chiral L2/Z*-type ligands to improve asymmetric catalysis.

In recent years, there have been increasing efforts in the development of methodologies for incorporating fluorine-containing functional groups into organic scaffolds. Modern techniques have made fluorinated molecules more accessible than ever before, but many fluorination reactions still have limitations in their generality, predictability, sustainability, and cost-effectiveness. The methodological progress has a significant impact on drug discovery and materials science research. Photoredox catalysis has enabled the discovery of effective methods, providing access to druglike molecules. Photochemical methods paired with C–H functionalization provide powerful tools for property-driven research. Herein, we examine recent developments at the interface of photoredox catalysis and C–H functionalization.1 Introduction2 Fluorinations3 Fluoroalkylations4 Fluoroalkoxylations5 Conclusion

A mild and efficient one-pot, three-component ball-mill-assisted reaction of aldehydes, anilines, and dihydrofuran (or dihydropyran and cyclohexenone) has been described for the first time in the presence of the catalytic amount of aqueous perchloric acid (8 mol%) at room temperature under organic solvent- and metal-free conditions. The reactions are fast (1 h), providing the products with excellent yields and high diastereoselectivity. This procedure endows a simple, efficient, and cost-effective method for the diastereoselective synthesis of furano- and pyrano-tetrahydroquinolines and phenanthridinone derivatives, which are important biological compounds. The diastereomers with cis configuration were isolated as major products. The H–H COSY, NOESY experiments and X-ray crystallographic analysis of selected compounds were performed to confirm the cis isomer. The synthesized tetrahydroquinolines have been evaluated in vitro for their antibacterial and anticancer activities, and it was found that both the prepared compounds showed significant antibacterial and anticancer properties.

A simple, cost-effective, and modular strategy has been developed to synthesize synthetically and pharmaceutically active enaminones by oxidative amination of aryl alkenes with amines and CHCl3, using tert-butyl hydroperoxide as an oxidant. We describe the synthesis of enaminones from vinyl arenes and sterically hindered N,N-diisopropylethylamine (DIPEA) by employing an Earth-abundant cobalt salt as a catalyst within a very short reaction period for the first time. Furthermore, nitrogen- and oxygen-containing heterocyclic compounds have been synthesized from these highly functionalized enaminones. Moreover, various control experiments, such as radical trapping reaction, along with a Hammett analysis with various types of substituents on the styrene ring unraveled the detailed mechanism of this reaction pathway.

Aging alcohol is a timeless process that has seen little variation since the time of its invention. Molecules stored within the wood can be extracted by the alcohol to produce unique flavors. Among these molecules exist the whiskey and cognac lactones. Herein we report a short synthesis of the trans-whiskey and cognac lactones using a rearrangement of cyclopropane hemimalonates.