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Decarboxylative halogenation reactions of alkyl carboxylic acids are highly valuable reactions for the synthesis of structurally diverse alkyl halides. However, many reported protocols rely on stoichiometric strong oxidants or highly electrophilic halogenating agents. Herein, we describe visible‐light photoredox‐catalyzed decarboxylative halogenation reactions of N‐hydroxyphthalimide‐activated carboxylic acids that avoid stoichiometric oxidants and use inexpensive inorganic halide salts as the halogenating agents. Bromination with lithium bromide proceeds under simple, transition‐metal‐free conditions using an organic photoredox catalyst and no other additives, whereas dual photoredox‐copper catalysis is required for chlorination with lithium chloride. The mild conditions display excellent functional‐group tolerance, which is demonstrated through the transformation of a diverse range of structurally complex carboxylic acid containing natural products into the corresponding alkyl bromides and chlorides. In addition, we show the generality of the dual photoredox‐copper‐catalyzed decarboxylative functionalization with inorganic salts by extension to thiocyanation with potassium thiocyanide, which was applied to the synthesis of complex alkyl thiocyanates. [ABSTRACT FROM AUTHOR]

A catalytic amount of CsI enables dual concurrent activation of poorly reactive perfluoroalkoxide and alkyl halides, especially alkyl chlorides, leading to the formation of diverse perfluoroalkoxylated organic compounds. Installation of perfluoroalkoxy groups by this methodology is cost-effective, circumventing the need for over-stoichiometric cesium or silver salts. This methodology also provides high functional group compatibility and tolerance of sterically hindered substrates. [ABSTRACT FROM AUTHOR]

We describe here the development of a visible light driven nickel carbonylation catalyst. The combination of the large bite‐angle Xantphos ligand with nickel(0) generates a catalyst capable of activating alkyl halides toward carbonylation at ambient temperature in the presence of blue light irradiation, and the reductive elimination of high energy acid chloride products. Unlike classical carbonylations, where the coordination of carbon monoxide inhibits the reactivity of earth abundant nickel catalysts, a CO‐associated nickel is found to be the active catalyst in the reaction. Coupling the build‐up of acid chlorides with nucleophile addition can be used to access various amides, esters and thioesters, including those of sterically encumbered substrates or with metal‐reactive functionalities. [ABSTRACT FROM AUTHOR]

Isolable stannenolates LKSn[(CO)R]3 (R=2,4,6‐trimethylphenyl (1 a, b), L=DME for (1 a) or 18‐crown‐6 for (1 b)), a new building block for the synthesis of effective Sn‐based photoinitiators, were synthesized. The formation of these derivatives was confirmed by NMR spectroscopy, UV/Vis spectroscopy as well as X‐ray crystallographic analysis. Compound 1 a is employed as a synthon in main group chemistry through reactions with two different types of electrophiles (acid chlorides and alkyl halides). All investigated electrophiles react via the salt metathesis reaction and gave rise to novel acylstannanes in good to excellent yields. The applicability as visible light photoinitiators is demonstrated by photobleaching (UV/Vis absorption spectroscopic studies) as well as through application in photo‐DSC studies. [ABSTRACT FROM AUTHOR]

The 6-substitued pyridyl group provided the driving force for chain-walking and the introduction of the hydroxyl group into oxazoline significantly accelerated the oxidative halogenation of C SB L sb -Pd SP II sp species. The development of remote functionalization of alkenes has recently gained considerable attention as it offers the opportunity to directly transform a mixture of unrefined olefin isomers into a single valuable fine chemical by means of a chain-walking strategy [[1], [3]]. [Extracted from the article]

Electrochemical catalytic reductive cross couplings are powerful and sustainable methods to construct C−C bonds by using electron as the clean reductant. However, activated substrates are used in most cases. Herein, we report a general and practical electro-reductive Ni-catalytic system, realizing the electrocatalytic carboxylation of unactivated aryl chlorides and alkyl bromides with CO2. A variety of unactivated aryl bromides, iodides and sulfonates can also undergo such a reaction smoothly. Notably, we also realize the catalytic electrochemical carboxylation of aryl (pseudo)halides with CO2 avoiding the use of sacrificial electrodes. Moreover, this sustainable and economic strategy with electron as the clean reductant features mild conditions, inexpensive catalyst, safe and cheap electrodes, good functional group tolerance and broad substrate scope. Mechanistic investigations indicate that the reaction might proceed via oxidative addition of aryl halides to Ni(0) complex, the reduction of aryl-Ni(II) adduct to the Ni(I) species and following carboxylation with CO2. Electrochemistry is a promising approach to make existing chemical protocols milder, but many simple transformations of feedstocks are still out of reach. Here, the authors transform unactivated aryl and alkyl (pseudo)halides into carboxylic acids, via nickel catalysis and electricity, using atmospheric CO2 as the carbon source. [ABSTRACT FROM AUTHOR]

We have synthesized the first isolable geminal bisenolates L2K2Ge[(CO)R]2 (R=2,4,6‐trimethylphenyl (2 a,b), L=THF for (2 a) or [18]‐crown‐6 for (2 b)), a new synthon for the synthesis of organometallic reagents. The formation of these derivatives was confirmed by NMR spectroscopy and X‐ray crystallographic analysis. The UV/Vis spectra of these anions show three distinct bands, which were assigned by DFT calculations. The efficiency of 2 a,b to serve as new building block in macromolecular chemistry is demonstrated by the reactions with two different types of electrophiles (acid chlorides and alkyl halides). In all cases the salt metathesis reaction gave rise to novel Ge‐based photoinitiators in good yields. [ABSTRACT FROM AUTHOR]

An unprecedented and general titanium‐catalyzed boration of alkyl (pseudo)halides (alkyl‐X, X=I, Br, Cl, OMs) with borane (HBpin, HBcat) is reported. The use of titanium catalyst can successfully suppress the undesired hydrodehalogenation products that prevail using other transition‐metal catalysts. A series of synthetically useful alkyl boronate esters are readily obtained from various (primary, secondary, and tertiary) alkyl electrophiles, including unactivated alkyl chlorides, with tolerance of other reducing functional groups such as ester, alkene, and carbamate. Preliminary studies on the mechanism revealed a possible radical reaction pathway. Further extension of our strategy to aryl bromides is also demonstrated. [ABSTRACT FROM AUTHOR]

Esterification reactions are central to many aspects of industrial and biological chemistry. The formation of carboxyesters typically occurs through nucleophilic attack of an alcohol onto the carboxylate carbon. Under certain conditions employed in organic synthesis, the carboxylate nucleophile can be alkylated to generate esters from alkyl halides, but this reaction has only been observed transiently in enzymatic chemistry. Here, we report a carboxylate alkylating enzyme – BrtB – that catalyzes O-C bond formation between free fatty acids of varying chain length and the secondary alkyl halide moieties found in the bartolosides. Guided by this reactivity, we uncovered a variety of natural fatty acid-bartoloside esters, previously unrecognized products of the bartoloside biosynthetic gene cluster. O-alkylation of carboxylates by alkyl halides has only been observed transiently in enzymatic processes. Here, the authors show a carboxylate alkylating enzyme, BrtB, that catalyzes C-O bond formation between free fatty acids and secondary alkyl chlorides. [ABSTRACT FROM AUTHOR]

The development of a nickel-catalyzed C–H alkylation of aromatic substrates with unactivated alkyl halides is described. This carbocyclization facilitates the synthesis of diverse fused ring systems from simple aromatic substrates and is an attractive alternative to traditional polar or radical-mediated ring formations. The present system uses unactivated primary and secondary alkyl bromides and chlorides, while avoiding the use of precious palladium catalysts and more reactive alkyl halides commonly used in related C–H alkylations. Image 1 [ABSTRACT FROM AUTHOR]

The chemical inertness of abundant and commercially available alkyl chlorides precludes their widespread use as reactants in chemical transformations. Presented in this work is a metallaphotoredox methodology to achieve the catalytic intramolecular reductive cyclization of unactivated alkyl chlorides with tethered alkenes. The cleavage of strong C(sp3)−Cl bonds is mediated by a highly nucleophilic low‐valent cobalt or nickel intermediate generated by visible‐light photoredox reduction employing a copper photosensitizer. The high basicity and multidentate nature of the ligands are key to obtaining efficient metal catalysts for the functionalization of unactivated alkyl chlorides. The chemical inertness of abundant and commercially available alkyl chlorides precludes their widespread use as reactants in chemical transformations. Presented here is a methodology to achieve the catalytic intramolecular reductive cyclization of unactivated alkyl chlorides with tethered alkenes. The cleavage of strong C(sp3)−Cl bonds is mediated by either a highly nucleophilic low‐valent cobalt or nickel intermediate, generated by employing a copper photosensitizer in a visible‐light photoredox reduction. [ABSTRACT FROM AUTHOR]

Direct fluorination of tertiary alkyl bromides and iodides with Selectfluor is described. The halogen-exchange fluorination proceeds efficiently in acetonitrile at room temperature under metal-free conditions and exhibits a wide range of functional group compatibility. Furthermore, the reactions are highly selective in that alkyl chlorides and primary and secondary alkyl bromides remain intact. A radical mechanism is proposed for this selective fluorination. [ABSTRACT FROM AUTHOR]

The use of low-cost manganese(II) bromide (MnBr2) and tetramethylethylenediamine (TMEDA) catalyzes the cross coupling of (bis)pinacolatodiboron with a wide range of alkyl halides, demonstrating the first manganese-catalyzed coupling with alkyl electrophiles. This method allows access to primary, secondary, and tertiary boronic esters from the parent chlorides, which were previously inaccessible as coupling partners. The reaction proceeds in high yield with as little as 1000 ppm catalyst loading, while 5 mol % can provide high yields in as little as 30 min. Finally, radical-clock experiments revealed that at 0 °C direct borylation outcompetes alternative radical processes, thereby providing synthetically useful, temperature-controlled reaction outcomes. [ABSTRACT FROM AUTHOR]

An efficient alkylation method of functionalized alkyl halides under mild nickel-catalyzed C( sp3)C( sp2) Suzuki cross-coupling conditions is described. The features of this approach are excellent functional group compatibility, low cost nickel catalyst, and the use of a mild base. This is also the first successful example of the nickel-catalyzed direct 2,2-difluoroethylation or 2,2,2-trifluoroethylation of aryl-/heteroarylboronic acids. [ABSTRACT FROM AUTHOR]

A cobalt-N-heterocyclic carbene catalytic system promotes pyridine-directed olefinic C-H alkylation reactions using a variety of primary and secondary alkyl chlorides under mild conditions. Radical clock experiments suggest that the reaction involves single-electron transfer from the cobalt intermediate to the alkyl chloride. [ABSTRACT FROM AUTHOR]

We report here cobalt-N-heterocyclic carbene catalytic systems for the ortho alkylation of aromatic imines with alkyl chlorides and bromides, which allows the introduction of a variety of primary and secondary alkyl groups at room temperature. The stereochemical outcomes of the reaction of secondary alkyl halides suggest that the present reaction involves single-electron transfer from a cobalt species to the alkyl halide to generate the corresponding alkyl radical. A cycloalkylated product obtained by this method can be transformed into unique spirocycles through manipulation of the directing and cycloalkyl groups. [ABSTRACT FROM AUTHOR]

Alkylation of p-tert-butylcalix[4]arenes with alkyl bromides or iodides under microwave irradiation affords mostly the corresponding distal disubstituted ethers, whereas in case of alkyl chlorides reasonable yields of monoethers were achieved. [Copyright &y& Elsevier]

• Step-economical synthesis. • Metal-free conditions. • Without super acid or base. • Simple and widely available starting materials. • Avoidance of over-oxidation. An efficient and step-economical access to sulfoxides from thiols and alkyl halides in the presence of I 2 O 5 and DBU via direct oxidative couplings is described here. It is the first case that combined Williamson sulfide synthesis and subsequent sulfide oxidation into one step manipulation for sulfoxides preparation. This protocol features wide substrate scope, mild and metal-free conditons, the use of naturally abundant starting materials and avoidance of over-oxidation. [ABSTRACT FROM AUTHOR]