The generation of carbon-centered radicals from air-sensitive organoboron compounds via nucleohomolytic substitution at boron is one of the most general methods to generate non-functionalized and functionalized radicals. Due to their reduced Lewis acidity, the very popular, air-stable, and readily available alkylboronic pinacol esters are not suitable substrates for this process. Herein, is reported their in situ conversion to alkylboronic catechol esters by boron-transesterification with a substoichiometric amount of catechol methyl borate (MeO-Bcat) telescoped onto a wide array of radical chain processes. This simple one-pot, radical-chain, deboronative protocol allows for the conversion of pinacol boronic esters into iodides, bromides, chlorides, and thioethers. The process is also suitable the formation of nitriles and allylated compounds via CC bond formation using sulfonyl radical traps. Finally, a particularly mild protocol for the protodeboronation of pinacol boronic esters is given. The power of combining radical and classical boron chemistry, is illustrated with a highly modular 5-membered ring formation using a combination of a three-component coupling reaction and a protodeboronative cyclization. File list (2) download file view on ChemRxiv pinacolboronicesters_ChemRiv.pdf (463.92 KiB) download file view on ChemRxiv SI_full_final _ChemRiv.pdf (8.05 MiB)

All fluorochemicals—including elemental fluorine and nucleophilic, electrophilic, and radical fluorinating reagents—are prepared from hydrogen fluoride (HF). This highly toxic and corrosive gas is produced by the reaction of acid-grade fluorspar (>97% CaF 2 ) with sulfuric acid under harsh conditions. The use of fluorspar to produce fluorochemicals via a process that bypasses HF is highly desirable but remains an unsolved problem because of the prohibitive insolubility of CaF 2 . Inspired by calcium phosphate biomineralization, we herein disclose a protocol of treating acid-grade fluorspar with dipotassium hydrogen phosphate (K 2 HPO 4 ) under mechanochemical conditions. The process affords a solid composed of crystalline K 3 (HPO 4 )F and K 2− x Ca y (PO 3 F) a (PO 4 ) b , which is found suitable for forging sulfur-fluorine and carbon-fluorine bonds.

The synthesis of benzimidazole-fused iminosugars through a tandem β-fragmentationintramolecular cyclization reaction is described. The use of the benzimidazole ring as the internal nucleophile as well as the use of phenyliodosophthalate (PhI(Phth)), a new metal-free and low toxic hypervalent iodine reagent, are the most remarkable novelties of this synthetic strategy. With this approach, we have demonstrated the usefulness of the fragmentation of anomeric alkoxyl radicals (ARF) promoted by the PhI(Phth)/I 2 system for the preparation of new compounds with potential interest for both medicinal and synthetic chemists.

The generation of carbon-centered radicals from airsensitive organoboron compounds through nucleohomolytic substitution at boron is ag eneral method to generate nonfunctionalizeda nd functionalized radicals.D ue to their reduced Lewis acidity,a lkylboronic pinacol esters are not suitable substrates.W er eport their in situ conversion into alkylboronic catechol esters by boron-transesterification with as ubstoichiometric amount of catechol methyl borate combined with an arrayofradical chain processes.This simple onepot radical-chain deboronative method enables the conversion of pinacol boronic esters into iodides,bromides,chlorides,and thioethers.The process is also suitable the formation of nitriles and allylated compounds through C À Cb ond formation using sulfonyl radical traps.T he power of combining radical and classical boron chemistry is illustrated with am odular 5membered ring formation using ac ombination of threecomponent coupling and protodeboronative cyclization.

A water-soluble "NSO" complexing agent was designed for polonium(iv) decorporation. The bifunctional ligand showed outstanding Po(iv) complexing abilities, with a conditional stability constant three orders of magnitude higher than the reference ligand BAL.

Radicals can be generated by the cleavage of the C—B bond of alkylboranes or boronic acid derivatives. The fragmentation process may result from a nucleohomolytic substitution process or from a redox process. The nucleohomolytic substitution is ideal for the generation of alkyl radicals and is usually part of a chain-reaction process. Redox processes (mainly oxidative reactions) have been used to generate both alkyl and aryl radicals. The use of stoichiometric oxidizing agents can be avoided by employing photoredox catalysis. A broad range of synthetic applications such as radical cascade processes, multicomponent reactions, and cross-coupling reactions in the presence of suitable metal catalysts are now possible. In their diversity, organoboron compounds represent one of the most general sources of radicals. The merging of radical chemistry with the classical chemistry of organoboron derivatives opens tremendous opportunities for applications in organic synthesis.

This chapter focuses on the use of boron‐containing reagents in radical reactions. In all reactions presented here, boron is playing a key role in the radical process either by being part of the radical process or by influencing the reactivity of the radical and nonradical species. The diversity of radical chemistry involving organoboron species is spectacular. They represent a unique source of radicals for chain reactions allowing for instance efficient radical initiation at low temperature and generation of a broad range of functionalized alkyl radicals from easily prepared organoboranes. Recent developments in redox chemistry including photoredox catalysis, electrochemistry, and single‐electron‐transfer processes have allowed the generation of alkyl and aryl radicals from stable organoboron derivatives such as alkyl‐ and aryl‐trifluoroborates. A broad range of synthetic applications such as radical cascade processes, multicomponent reactions, and cross‐coupling reactions in the presence of suitable metals are possible. Besides radical generation, boron‐containing radical precursors and radical traps are becoming of increasing importance to prepare building blocks enclosing a boron moiety suitable for further functionalization. Merging radical processes with classical boron chemistry including Suzuki–Miyaura‐type cross‐coupling processes; homologation via 1,2‐metallate rearrangement; and conversions to alcohols, amines, and related compounds offers unique opportunities for applications in organic synthesis.

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