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1. Friedel–Crafts Reactions with N -Heterocyclic Alcohols

   https://doi.org/10.1021/acs.joc.3c00403  

   Hood, Jacob C.; Anokhin, Maksim V.; Klumpp, Douglas A. (July 2023, The Journal of Organic Chemistry)
2. Cationic cobalt(I) intermediates in hydrofunctionalization reactions

   Parsutkar, Mahesh; Jing, Stanley; Duvvuri, Krishnaja.; RajanBabu, T. V. (April 2020, Book of Abstracts, 259th ACS National Meeting, Philadelphia, PA, March 22-26 2020.)

   Discovery of base metal-catalyzed methods for the preparation of chiral intermediates has garnered great attention. Recently, through a systematic study of activators and ligands, we have discovered Co(I)-catalyzed enantioselective heterodimerization of linear 1,3-dienes with ethylene and acrylates. In these studies, cationic cobalt(I) has been invoked as an active catalyst to carry out the transformation. However, the synthesis and isolation of such active Co(I)-complexes which could give insight into of reaction’s mechanism, remains challenging. Herein, we disclosed a reliable procedure for the synthesis and isolation of Co(I)-complexes and characterized them by UV-Vis spectroscopy and X-ray crystallography. The bis-phosphine ligated Co(I) complexes in presence of activators, performed the regio- and enantioselective hydroboration of 2- substituted 1,3-diene with pinacolborane (HBPin) to obtain homoallylic boronates (enantiomeric excess, ee >90%). In the absence of activators, these complexes do not catalyze the reaction suggesting the key role of cationic Co(I)-species in the catalytic cycle. Currently, these Co(I) complexes are being further utilized in the hydroacylation of 1,3-dienes with simple aliphatic aldehyde to produce enantiopure ketones. The comprehensive protocols for the synthesis of Co(I) complexes and its application in hydrovinylation, heterodimerization with acrylates, hydroboration, and hydroacylation of 1,3-dienes will be discussed. 

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3. Exploring mechanochemical reactions at the nanoscale: theory versus experiment

   https://doi.org/10.1039/D3CP00980G  

   Hopper, Nicholas; Sidoroff, François; Rana, Resham; Bavisotto, Robert; Cayer-Barrioz, Juliette; Mazuyer, Denis; Tysoe, Wilfred T. (June 2023, Physical Chemistry Chemical Physics)

   Mechanochemical reaction pathways are conventionally obtained from force-displaced stationary points on the potential energy surface of the reaction. This work tests a postulate that the steepest-descent pathway (SDP) from the transition state to reactants can be reasonably accurately used instead to investigate mechanochemical reaction kinetics. This method is much simpler because the SDP and the associated reactant and transition-state structures can be obtained relatively routinely. Experiment and theory are compared for the normal-stress-induced decomposition of methyl thiolate species on Cu(100). The mechanochemical reaction rate was calculated by compressing the initial- and transition-state structures by a stiff copper counter-slab to obtain the plots of energy versus slab displacement for both structures. The reaction rate was also measured experimentally under compression using a nanomechanochemical reactor comprising an atomic-force-microscopy (AFM) instrument tip compressing a methyl thiolate overlayer on Cu(100) (the same system for which the calculations were carried out). The rate was measured from the indent created on a defect-free region of the methyl thiolate overlayer, which also enabled the contact area to be measured. Knowing the force applied by the AFM tip yields the reaction rate as a function of the contact stress. The result agrees well with the theoretical prediction without the use of adjustable parameters. This confirms that the postulate is correct and will facilitate the calculation of the rates of more complex mechanochemical reactions. An advantage of this approach, in addition to the results agreeing with the experiment, is that it provides insights into the effects that control mechanochemical reactivity that will assist in the targeted design of new mechanochemical syntheses. 

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4. Asymmetric [3+ n ]‐Cycloaddition Reactions of Donor‐Acceptor Cyclopropanes

   https://doi.org/10.1002/cctc.202301090  

   Bao, Ming; Doyle, Michael_P (November 2023, ChemCatChem)

   Abstract [3+n]‐Cycloaddition reactions that employ donor‐acceptor cyclopropanes using either chiral catalysts and racemic cyclopropanes or achiral catalysts and chiral, non‐racemic, cyclopropanes have become useful transformations for the construction of carbocyclic and heterocyclic compounds, with both processes offering mechanistic and structural advantages in ring formation. Although the vast majority of asymmetric cycloaddition reactions of donor‐acceptor cyclopropanes have been performed with racemic cyclopropane compounds catalyzed by Lewis acids with chiral ligands, optically active cyclopropane compounds can serve the same role using Lewis acids without chiral ligands. This review covers the use of chiral catalysts with racemic donor‐acceptor cyclopropanes and the use of chiral non‐racemic donor‐acceptor cyclopropanes with achiral Lewis acid catalysts. 

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5. Transformation of N , N -Dimethylaniline N -Oxides into Diverse Tetrahydroquinoline Scaffolds via Formal Povarov Reactions

   https://doi.org/10.1021/acs.orglett.8b02318  

   Bush, Timothy S.; Yap, Glenn P.; Chain, William J. (August 2018, Organic Letters)