Electrochemical Borylation of Carboxylic Acids

A simple electrochemically mediated method for the conversion of alkyl carboxylic acids to their borylated congeners is presented. This protocol features an undivided cell setup with inexpensive carbon-based electrodes and exhibits a broad substrate scope and scalability in both flow and batch reactors. The use of this method in challenging contexts is exemplified with a modular formal synthesis of jawsamycin, a natural product harboring five cyclopropane rings

The Choice Is Yours: Using Liquid-Assisted Grinding To Choose between Products in the Palladium-Catalyzed Dimerization of Terminal Alkynes

Herein, we report on the dimerization of terminal alkynes using various palladium catalysts under solvent-free mechanochemical conditions. When tetrakis­(triphenylphosphine)­palladium(0) was employed as the catalyst, we observed the 1,3-butadiyne as the major product. However, when we employed bis­(triphenylphosphine)­palladium­(II) dichloride as the catalyst, we observed the <i>trans</i>-enyne as the major product. When we used a polymer-supported bis­(triphenylphosphine)­palladium­(II) dichloride catalyst under liquid-assisted grinding conditions, we discovered the ability to tune the catalyst to generate either the diyne or <i>trans</i>-enyne as the major product, depending on the grinding medium

Chemoselective, Scalable Nickel-Electrocatalytic O-Arylation of Alcohols

The formation of aryl-alkyl ether bonds through cross coupling of alcohols with aryl halides represents a useful strategic departure from classical SN2 methods. Numerous tactics relying on Pd-, Cu-, and Ni-based catalytic systems have emerged over the past several years. Herein we disclose a Ni-catalyzed electrochemically driven protocol to achieve this useful transformation with a broad substrate scope in an operationally simple way. This electrochemical method does not require strong base, exogenous expensive transition metal catalysts (e.g. Ir, Ru), and can easily be scaled up in either a batch or flow setting. Interestingly, e-etherification exhibits an enhanced substrate scope over the mechanistically related photochemical variant as it tolerates tertiary amine functional groups in the alcohol nucleophile

A High Fidelity Simulation Framework for Potential Safety Benefits Estimation of Cooperative Pedestrian Perception

This paper proposes a high-fidelity simulation framework that can estimate the potential safety benefits of vehicle-to-infrastructure (V2I) pedestrian safety strategies. This simulator can support cooperative perception algorithms in the loop by simulating the environmental conditions, traffic conditions, and pedestrian characteristics at the same time. Besides, the benefit estimation model applied in our framework can systematically quantify both the risk conflict (non-crash condition) and the severity of the pedestrian's injuries (crash condition). An experiment was conducted in this paper that built a digital twin of a crowded urban intersection in China. The result shows that our framework is efficient for safety benefit estimation of V2I pedestrian safety strategies.Comment: The content needs to be modifie

Cobalt-Electrocatalytic Hydrogen Atom Transfer for Functionalization of Unsaturated C–C Bonds

The study and application of transition metal hydrides (TMH) has been an active area of chemical research since the early 1960’s. The use of TMHs has been broadly bifurcated into fields focused on energy storage through the reduction of protons to generate hydrogen and in organic synthesis for the functionalization of unsaturated C–C, C–O, and C–N bonds. In the former instance, electrochemical means for driving such reactivity has been commonplace since the 1950’s. In contrast, the use of stoichiometric exogenous organic and metal-based reductants to harness the power of TMHs in synthetic chemistry remains the norm. In particular, Co-based TMHs have found widespread use for the derivatization of olefins and alkynes in complex molecule construction, often via a net hydrogen atom transfer (HAT). Here, we show how an electrocatalytic approach inspired by decades of energy storage precedent can be leveraged in the context of modern organic synthesis. Such an approach not only offers benefits in terms of sustainability and efficiency but also enables enhanced chemoselectivity and unique and tunable reactivity. Ten different reaction manifolds across dozens of substrates are thus exemplified, along with a detailed mechanistic and computational analysis of this scalable electrochemical entry into Co-H chemistry

N-Ammonium Ylide Mediators for Selective Electrochemical C–H Oxidation

The site-specific oxidation of strong C(sp3)-H bonds is of uncontested utility in organicsynthesis. From simplifying access to metabolites and late-stage diversification of lead compoundsto truncating retrosynthetic plans, there is a growing need for new reagents and methods forachieving such a transformation in both academic and industrial circles. One main drawback ofcurrent chemical reagents is the lack of diversity with regards to structure and reactivity thatprevent a combinatorial approach for rapid screening to be employed. In that regard, directedevolution still holds the greatest promise for achieving complex C–H oxidations in a variety ofcomplex settings. Herein we present a rationally designed platform that provides a step towardsthis challenge using N-ammonium ylides as electrochemically driven oxidants for site-specific,chemoselective C(sp3)–H oxidation. By taking a first-principles approach guided by computation,these new mediators were identified and rapidly expanded into a library using ubiquitous buildingblocks and trivial synthesis techniques. The ylide-based approach to C–H oxidation exhibitstunable selectivity that is often exclusive to this class of oxidants and can be applied to real worldproblems in the agricultural and pharmaceutical sectors.</p

Electrochemically Driven, Ni-Catalyzed Aryl Amination: Scope, Mechanism, and Applications

C–N cross-coupling is one of the most valuable and widespread transformations in organic synthesis. Largely dominated by Pd- and Cu-based catalytic systems, it has proven to be a staple transformation for those in both academia and industry. The current study presents the development and mechanistic understanding of an electrochemically driven, Ni-catalyzed method for achieving this reaction of high strategic importance. Through a series of electrochemical, computational, kinetic, and empirical experiments the key mechanistic features of this reaction have been unraveled, leading to a second generation set of conditions that is applicable to a broad range of aryl halides and amine nucleophiles, including complex examples on oligopeptides, medicinally-relevant heterocycles, natural products, and sugars. Full disclosure of the current limitations as well as procedures for both batch and flow scale-ups (100 gram) are also described. </div