Enantioselective S−H Insertion Reactions of α‐Carbonyl Sulfoxonium Ylides

Gong

Chemistry An Asian Journal

et al. 2022

Described herein is a B(C 6 F 5 ) 3 -catalyzed SÀ H insertion reaction of thiophenols and thiols with α-diazoesters to access valuable α-thioesters. With the established protocol, an array of α-thioester products are generated in moderate to good yields with broad scope and functional group tolerance. In addition, this reaction maintains its high efficiency on gram scale and the product can be easily transformed into other useful motifs. This reaction proceeds under solvent-free conditions at room temperature, and generally finishes in twenty minutes upon magnet stirring, which offers an expedient way for the synthesis of thioethercontaining compounds.

Section: Resultsmentioning

confidence: 99%

Solvent‐free, B(C₆F₅)₃‐Catalyzed S−H Insertion of Thiophenols and Thiols with α‐Diazoesters

Gong

Chemistry An Asian Journal

et al. 2022

“…Activation energies (or activation barriers, used interchangeably here) can be evaluated by modeling reactions with quantum mechanical (QM) calculations, particularly density functional theory (DFT) 6,7 . DFT has played a major role in calculating activation energies of reactions in several valuable areas of chemistry including: mechanistic modeling of organic reactions, 8–12 drug design, 12–14 toxicology, 15,16 and catalyst design 17–19 . However, accurate QM and DFT calculations incur a significant computational expense 20–22 and their practicality for reaction modeling on a large scale is thus limited.…”

Section: Introductionmentioning

confidence: 99%

Machine learning activation energies of chemical reactions

Lewis‐Atwell

Townsend

Grayson

2021

WIREs Comput Mol Sci

Self Cite

Application of machine learning (ML) to the prediction of reaction activation barriers is a new and exciting field for these algorithms. The works covered here are specifically those in which ML is trained to predict the activation energies of homogeneous chemical reactions, where the activation energy is given by the energy difference between the reactants and transition state of a reaction. Particular attention is paid to works that have applied ML to directly predict reaction activation energies, the limitations that may be found in these studies, and where comparisons of different types of chemical features for ML models have been made. Also explored are models that have been able to obtain high predictive accuracies, but with reduced datasets, using the Gaussian process regression ML model. In these studies, the chemical reactions for which activation barriers are modeled include those involving small organic molecules, aromatic rings, and organometallic catalysts. Also provided are brief explanations of some of the most popular types of ML models used in chemistry, as a beginner's guide for those unfamiliar.

“…9 During the preparation of this article, Burtoloso and co-workers reported an elegant S−H insertion of arylthiols with α-ester sulfoxonium ylides by chiral thiourea catalysis, leading to a range of α-arylthio esters in 45−95% ee. 10 Notably, in contrast to the α-ester sulfur ylides, asymmetric insertion using α-keto sulfur ylides has not been realized. We envisioned that these reactions may remedy some of the drawbacks encountered with α-diazoketones.…”

Section: ■ Introductionmentioning

confidence: 99%

Chiral Phosphoric Acid Catalyzed Enantioselective Synthesis of α-Tertiary Amino Ketones from Sulfonium Ylides

et al. 2020

Herein we disclose a new catalytic asymmetric approach for the synthesis of chiral α-amino ketones, which is particularly useful for the less accessible acyclic α-tertiary cases. By a protonation−amination sequence, our approach represents a rare asymmetric H−heteroatom bond insertion by αcarbonyl sulfonium ylides, an attractive surrogate of diazocarbonyls. The mild intermolecular C−N bond formation was catalyzed by chiral phosphoric acids with excellent efficiency and enantioselectivity. The products are precursors to other important chiral amine derivatives, including drug molecules and chiral ligands. The enantioselectivity was controlled by dynamic kinetic resolution in the amination step, rather than the initial protonation. This process opens up a new platform for the development of other related insertion reactions.