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1. Enantioselective regiospecific addition of propargyltrichlorosilane to aldehydes catalyzed by biisoquinoline N , N’ -dioxide

   https://doi.org/10.3762/bjoc.20.255  

   Brako, Noble; Narayanan, Sreerag Moorkkannur; Burns, Amber; Auter, Layla; Cesiliano, Valentino; Prabhakar, Rajeev; Takenaka, Norito (January 2024, Beilstein Journal of Organic Chemistry)

   Distilled propargyltrichlorosilane with >99% isomeric purity was prepared for the first time, and its asymmetric catalytic regiospecific addition reaction to aldehydes was developed through a systematic catalyst structure–reactivity and selectivity relationship study. The observed catalyst structure–enantioselectivity relationship of the present allenylation reaction was found exactly opposite to that of the analogous allylation reaction. The method provided eleven α-allenic alcohols in 22–99% yield with 61:39–92:8 enantiomeric ratios. Furthermore, possible mechanisms of propargyl–allenyl isomerization of propargyltrichlorosilane were computationally investigated. 

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2. Nitrogen-interrupted halo -Prins/ halo -Nazarov fragment coupling cascade for the synthesis of indolines

   https://doi.org/10.1039/d3sc00986f  

   Milosavljevic, Aleksa; Holt, Connor; Frontier, Alison J. (May 2023, Chemical Science)

   The nitrogen-interrupted Nazarov cyclization can be a powerful method for the stereocontrolled synthesis of sp 3 -rich N -heterocycles. However, due to the incompatibility between the basicity of nitrogen and the acidic reaction conditions, examples of this type of Nazarov cyclization are scarce. Herein, we report a one-pot nitrogen-interrupted halo -Prins/ halo -Nazarov coupling cascade that joins two simple building blocks, an enyne and a carbonyl partner, to furnish functionalized cyclopenta[ b ]indolines with up to four contiguous stereocenters. For the first time, we provide a general method for the alkynyl halo -Prins reaction of ketones, thus enabling the formation of quaternary stereocenters. Additionally, we describe the outcomes of secondary alcohol enyne couplings, which exhibit helical chirality transfer. Furthermore, we investigate the impact of aniline enyne substituents on the reaction and evaluate the tolerance of different functional groups. Finally, we discuss the reaction mechanism and demonstrate various transformations of the prepared indoline scaffolds, highlighting their applicability in drug discovery campaigns. 

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3. Charmonium, B _c and X(3872) Transport at the LHC

   https://doi.org/10.1051/epjconf/202327602001  

   Wu, Biaogang; Tang, Zhanduo; He, Min; Rapp, Ralf (January 2023, EPJ Web of Conferences)

   Kim, Y.; Moon, D.H. (Ed.)

   We deploy a kinetic-rate equation to evaluate the transport of J /ψ, ψ(2 S ), B c and X (3872) in ultrarelativistic heavy-ion collisions and compare their production yields to experimental data from the Large Hadron Collider. The rate equation has two main transport parameters: the equilibrium limit and reaction rate for each state. The temperature-dependent equilibrium limits include charm- and bottom-quark fugacities based on their initial production. The reaction rates for charmonia, bottomonia and B c rely on charm- and bottomquark masses and binding energies from a thermodynamic T -matrix approach. For the X (3872) particle, internal structure information is encoded in reaction rates and initial conditions in the hadronic phase via two different scenarios: a loosely bound hadronic molecule vs. a compact tetraquark. 

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4. Synthesis of oxaboranes via nickel-catalyzed dearylative cyclocondensation

   https://doi.org/10.1039/d2sc01840c  

   Koeritz, Mason T.; Banovetz, Haley K.; Prell, Sean A.; Stanley, Levi M. (July 2022, Chemical Science)

   We report Ni-catalyzed dearylative cyclocondensation of aldehydes, alkynes, and triphenylborane. The reaction is initiated by oxidative cyclization of the aldehyde and alkyne coupling partners to generate an oxanickelacyclopentene which reacts with triphenylborane to form oxaboranes. This formal dearylative cyclocondensation reaction generates oxaboranes in moderate-to-high yields (47–99%) with high regioselectivities under mild reaction conditions. This approach represents a direct and modular synthesis of oxaboranes which are difficult to access using current methods. These oxaboranes are readily transformed into valuable building blocks for organic synthesis and an additional class of boron heterocycles. Selective homocoupling forms oxaboroles, oxidation generates aldol products, and reduction and arylation form substituted allylic alcohols. 

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5. 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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