Robby Vroemans

Nature, Published online: 23 February 2023; doi:10.1038/d41586-023-00521-3

Publication date: 12 April 2023

Source: Tetrahedron Letters, Volume 119

Author(s): Rui Umeda, Shiori Shimaoka, Shintaro Mori, Tsubasa Takagishi, Yutaka Nishiyama

Carbonyl diisocyanate, CO(NCO)₂, and carbonyl diisothiocyanate, CO(NCS)₂, react differently with hydrogen halides HF, HCl, HBr and HI: Whereas carbonyl diisocyanate adds two equivalents thus forming carbonyl bis(carbamoylhalides), carbonyl diisothiocyanate only adds one equivalent and undergoes intramolecular ring closure, resulting in the formation of substituted thiadiazines.

Abstract

The reactivity of carbonyl diisocyanate, CO(NCO)₂, and carbonyl diisothiocyanate, CO(NCS)₂ with nucleophiles shows different patterns: Whereas carbonyl diisocyanate adds two equivalents of nucleophile forming carbonyl bis(carbamoylhalides), carbonyl diisothiocyanate only adds one equivalent and undergoes intramolecular ring closure, resulting in the formation of substituted thiadiazines. In this study we have reacted both carbonyl diisocyanate and carbonyl diisothiocyanate with the full series of hydrogen halides HF to HI, isolating carbonyl bis(carbamoylfluoride) (1), -chloride (2), -bromide (3), and -iodide (4) as well as (6-chloro-2,3-dihydro-2-thioxo-4H-1,3,5-thiadiazin-4-one (5), and 6-bromo-2,3-dihydro-2-thioxo-4H-1,3,5-thiadiazin-4-one (6). The compounds were analysed by single-crystal X-ray diffraction, NMR spectroscopy, IR and Raman spectroscopy, and elemental analysis. Quantum mechanical calculations show thermodynamic reasons for the differences in reactivity.

Nature, Published online: 13 February 2023; doi:10.1038/d41586-023-00403-8

Publication date: 21 March 2023

Source: Tetrahedron, Volume 134

Author(s): Zhenkun Chen, Fengzhi Zhang

Selective methods for single C−F transformations such as allylation, thiolation, azidation, and chlorination of o-hydrosilyl-substituted benzotrifluorides through the hydride abstraction with trityl cations are summarized. The resulting fluorosilyl group served in further transformations. These methods enabled us to prepare a broad range of organofluorines from simple benzotrifluorides through C−F and C−Si transformations.

Abstract

Single C−F transformations of aromatic trifluoromethyl compounds are challenging issues due to the strong C−F bond. We have recently developed selective methods for single C−F transformations such as allylation of o-hydrosilyl-substituted benzotrifluorides through the hydride abstraction with trityl cations. Single C−F thiolation and azidation of o-(hydrosilyl)benzotrifluorides were achieved using trityl sulfides and trityl azide catalyzed by Yb(OTf)₃. Treatment of o-(hydrosilyl)benzotrifluorides with trityl chloride resulted in single C−F chlorination. The resulting fluorosilyl group served in further transformations including protonation, halogenation, and Hiyama cross-coupling with C−Si cleavage. We also synthesized benzyl fluorides by LiAlH₄-reduction of the resulting fluorosilanes and further C−F transformations. These methods enabled us to prepare a broad range of organofluorines from simple benzotrifluorides through C−F and C−Si transformations.

Publication date: 1 March 2023

Source: Molecular Catalysis, Volume 538

Author(s): Luping Zhang, Xuewei Tu, Yutong Chen, Weihang Han, Liangchen Chen, Can Sun, Shouxin Zhu, Yanjiang Song, Hui Zheng

A rising star! Single-atom catalysis brings new opportunities in heterogeneous catalysis. This perspective highlights that single-atom catalysts can combine the advantages of homogeneous and heterogeneous catalysts, exemplified by recent progress in Rh atoms catalysed hydroformylation reactions. The expanded applications of materials bearing singly dispersed metal atoms, such as medicinal treatment, and gas selective adsorption, are discussed as well.

Abstract

The catalytic approaches fulfilled by the singly dispersed metal atoms anchoring on the solid materials were categorized as single-atom catalysis. In this perspective, after briefly introducing the history in this research field, we compare the differences between single-atom catalyst and several terms indicating some heterogeneous highly dispersed metal catalysts. Single-atom catalysts could provide the simplified models in exploring the catalytically active structures, and a new era of designing catalysts at the atomic scale is thus opened. In this context, single-atom catalysis may be regarded as a bridge to combine the homogeneous and heterogeneous catalysis. Moreover, the materials containing isolated metal centers also provide great opportunities in many other applications, such as medicinal treatment, selective separation of gas molecule, and quantum devices. At last, challenges to the single-atom catalysis are discussed.

The Front Cover displays transfer hydrogenation as a bridge between biomass and a bio-refinery. Biomass is considered as a sustainable alternative to petroleum-based resources and the effective use of biomass feedstock presents a crucial opportunity. For the sustainable development of biofuel and fine chemicals, lignocellulosic biomass may be established as one of the most promising carbon feedstocks. Therefore, the importance of bio-refineries is growing significantly in the present era. Each year bio-refineries are producing a huge amount of furfural and vanillin which are the source of important fine chemicals furfuryl alcohol and vanillyl alcohol, respectively, with wide applications. It is important to develop catalytic process such as catalytic transfer hydrogenation to reduce furfural and vanillin to furfuryl alcohol and vanillyl alcohol, respectively. In their Research Article, B. Bagh and co-workers have developed a base metal iron catalyst which proved to be a very effective catalyst for the transfer hydrogenation of biomass-model compounds furfural and vanillin to furfuryl alcohol and vanillyl alcohol, respectively.  More information can be found in the Research Article by B. Bagh and co-workers.

Cycloaddition of enamines leads to the formation of different cyclic compounds with highly valuable structures. This review highlights this topic, discussing advantages, limitations and mechanistic aspects of the related methods over the around two last decades.

Abstract

This review includes information for around two last decades on cycloaddition reactions of enamines with various agents in order to build carbo- and heterocycles. In addition, the review presents organo-catalytic reactions in which enamines are intermediate products generated in situ. This review covers the synthesis of four, five, six and eight-membered carbocyclic compounds, as well as heterocycles as pyrroles, pyridines, etc.

This personal account deals with typical fluorinated groups containing trifluoromethyl (CF₃), difluoromethyl (CF₂H), monofluoromethyl (CFH₂), monofluoro (F), or β-bromotetrafluoroethyl (BrCF₂CF₂) moieties in combination with vinyl sulfonium salts.

Abstract

The fluorinated building block strategy and the direct fluorination strategy are of great importance for the synthesis of new fluorinated molecules. These strategies complement each other and can be combined to develop a new methodology for the construction of a wide variety of fascinating organofluorine compounds. In our opinion, the versatile building blocks used in this method should satisfy the following conditions: 1) readily prepared from commercially available reagents; 2) easy to handle; 3) storage under ordinary conditions without noticeable decomposition; 4) wide applicability. Based on the aforementioned requirements, we focused on the use of vinyl sulfonium salts. This brief review describes the synthesis of five types of fluorinated vinyl sulfonium salts and their reactions. Especially, we featured typical fluorinated groups containing trifluoromethyl (CF₃), difluoromethyl (CF₂H), monofluoromethyl (CFH₂), monofluoro (F) or β-bromotetrafluoroethyl (BrCF₂CF₂) moieties in combination with vinyl sulfonium salts.