Synlett最新文献

Methanol is gaining popularity as a transfer-hydrogenating agent in catalytic reduction reactions because of its bulk-scale production and inexpensive nature. Current research interests include the utilization of methanol as a safe and sustainable hydrogen source for chemical synthesis and drug development. In particular, the chemoselective reduction of α,β-unsaturated ketones is of great interest because of their prevalence in many natural products. We investigated the potential application of acridine-derived SNS-Ru pincer complexes in methanol activation for chemoselective reduction of chalcones. Our developed catalytic system showed broad substrate tolerance, including substrates containing reducible functional groups. Control experiments and postsynthetic applications are also highlighted.

Dearomatization of indole derivatives offers a straightforward approach to accessing the indoline framework. However, highly efficient dearomatization of indoles bearing electron-deficient groups remains underdeveloped. Herein, a nickel-catalyzed intermolecular hydroalkylative dearomatization reaction of indoles with simple alkyl bromides through a single-electron-transfer process is reported. A wide variety of indole derivatives bearing various functional groups were compatible with this protocol and reacted with primary, secondary, or tertiary alkyl bromides to afford a series of indolines in good yields (up to 82%) and with excellent diastereoselectivity (up to >20:1). Notably, a nickel-mediated hydrogen-atom-transfer process was observed when terminal alkyl bromides were employed as the radical precursors, which resulted in branched products.

A Fe(OTf)₃ and γ-cyclodextrin-catalyzed hydroarylation of alkenes with 1-naphthols or 2-naphthols is demonstrated. This efficient and general method delivers a wide range of benzylic naphthols from readily available starting materials with high chemo- and regioselectivity in up to 99% yield, with no need for a strong base or additive.

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 Introduction

2 Synthesis and Resolution of the C₂-Symmetric Double Helical Tetraamine 2-H₂-C₂

3 Synthesis and Characterization of Neutral High-Spin Aminyl Diradical 2^2•-C₂

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.

Allylic C(sp³)–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 Introduction

2 Asymmetric Allylic Oxygenation

3 Asymmetric Allylic Amination

4 Asymmetric Allylic Carbonization

5 Asymmetric Allylic Sulfuration

6 Conclusion and Outlook

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.

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 Introduction

2 Fluorinations

3 Fluoroalkylations

4 Fluoroalkoxylations

5 Conclusion