Showing papers in "Organic Letters in 2020"

TL;DR: An efficient, photoredox-catalyst-free radical alkylation of quinoxalin-2(1H)-ones has been described and the synthetic value of the protocol was demonstrated by the successful functionalization of natural products and drug-based complex molecules.

TL;DR: NMR spectroscopy and kinetic analyses showed that the nucleophiles NaOtBu, Na[N(SiMe3)2], nBu2Mg, and nBuLi only promoted the formation of BH3 and were not "true" hydroboration catalysts.

TL;DR: An efficient, practical photocatalytic deoxygenation/defluorination protocol for the synthesis of γ,γ-difluoroallylic ketones from commercially available aromatic carboxylic acids, triphenylphosphine, and α-trifluoromethyl alkenes is described.

TL;DR: An unprecedented carbene-catalyzed radical trifluoromethylation of olefins with aldehydes in the presence of Togni reagent was developed, thus providing the β-trifluorbene-α-substituted ketones with a broad scope and moderate to high chemical yields.

TL;DR: A general and practical copper-catalyzed fluorosulfonylation reaction of a wide range of abundant arenediazonium salts to smoothly prepare various arenesulfonyl fluorides using the 1,4-diazabicyclo(sulfur dioxide) adduct as a convenient sulfonyl source in combination with KHF2 as an ideal fluorine source and without the need for additional oxidants.

TL;DR: The electrochemical synthesis of highly functionalized 1-naphthols using alkynes and 1,3-dicarbonyl compounds by (4 + 2) annulation of C-centered radical under electrochemical conditions showed good antitumor activity in vitro, and further studies indicated that compound 3bl induced tumor cell apoptosis.

TL;DR: An operationally simple one-pot palladium-catalyzed protocol introduces the sulfonyl group using sodium hydroxymethylsulfinate (Rongalite) as a source of SO22–.

TL;DR: An NHC-catalyzed radical relay enabled the vicinal alkylacylation of alkenes using aldehydes and tertiary α-bromo esters as a versatile route to δ-keto ester bearing an all-carbon quaternary center at the position α to the ester.

TL;DR: An efficient synthetic method of 3,4-unsubstituted isocoumarins adopting an electron-deficient CpERh complex as the catalyst is introduced and an unprecedented "rhodium shift" event within the catalytic cycle is found.

TL;DR: The electrosynthesis offers sustainable and efficient access to construct spirocyclohexadienone-containing (E)-indenes without any additional catalyst or oxidant through a sulfonyl-radical-triggered 1,6-addition and an I+-mediated ipso-cyclization cascade.

TL;DR: A mild and efficient protocol for the intramolecular aromatic C-H oxygenation of 2-biphenylcarboxylic acids has been achieved via iron photocatalysis and it is speculated that the aryl carboxylate-iron(III) complexes should generate the aroyloxy radicals and iron(II) upon visible light irradiation.

TL;DR: A Rh-catalyzed C-H/C-H vinylene cyclization adopting vinylene carbonate as a "vinylene transfer" agent achieves the direct annulative π-extension of imidazole- and pyrazole-fused aromatics.

TL;DR: The rhodium(III)-catalyzed coupling of C-H substrates with iodonium ylides has been realized for the efficient synthesis of diverse cyclic skeletons, where the iodOnium y lides have been identified as efficient and outstanding carbene precursors.

TL;DR: Mechanism studies suggest a previous elusive energy transfer pathway from photocatalyst to N-heteroarenes and oxidants is suggested.

TL;DR: This reaction was applied to a diverse set of sulfamides, sulfamates, and sulfonamides at room temperature under mild conditions and this transformation to parallel medicinal chemistry to generate a broad array of nitrogen-based S(VI) compounds is highlighted.

TL;DR: A novel synthesis of 3-Nitrosoindoles starting from easily available N-nitrosoanilines and sulfoxonium ylides via Rh(III)-catalyzed acylmethylation and trifluoroacetic acid (TFA)-mediated nitroso transfer/cyclization cascade reaction in one pot has been developed.

TL;DR: A photoinduced, copper-catalyzed, highly enantioselective dual alkylation/arylation and alkynylation of alkene is reported, which provides facile access to chiral propargylic systems, including those featuring valuable fluorinated substituents.

TL;DR: A mild and concise route to access the target compounds through the visible-light-mediated direct β-C-H gem-difluoroallylation of aliphatic aldehydes and cyclic ketones is reported.

TL;DR: A Bodipy derivative with twisted π-conjugation system is demonstrated that shows efficient intersystem crossing (ISC) and a long-lived triplet state with high energy with superior results to the conventional heavy-atom-enhanced ISC in a reference BodipY compound.

TL;DR: A mechanistic study revealed that a single electron transfer pathway might be involved in this reaction, and this protocol is used for free aminated 2H-indazole synthesis.

TL;DR: An environmentally friendly characteristic of this reaction is that it uses electricity as a valuable energy source for electrochemical synthesis of β-ketosulfones, which is more convenient and practical compared to previous approaches.

TL;DR: The practicality of this method was demonstrated by the broad functional group tolerance, gram-scale synthesis, and late-stage fluorosulfonylation of natural products and pharmaceuticals and the one-pot direct synthesis of sulfonyl fluorides from aromatic amines.

TL;DR: It is discovered that photoinduced intermolecular charge transfer induces a single-electron transfer event without requiring a photocatalyst for the facile functionalization of pyridines.

TL;DR: It is demonstrated that a figure-eight-shaped molecule with D2 symmetry has excellent chiroptical properties, which are attributed to the parallel arrangement of μ and m as well as a good |μ|/|m| ratio.

TL;DR: A photoredox-mediated cross-coupling and defluorinative alkylation process is introduced using commercially available alkyl bromides and structurally diverse α-silylamines for the incorporation of a variety of amino-acid-based organosilanes.

TL;DR: Using trifluoromethylation of (hetero)arenes as a model reaction, it is shown that the yield was improved from 13% using paired electrolysis to 84% using alternating current electrolysis (ACE).

TL;DR: A mild, versatile organophotoredox protocol has been developed that offers the unrivaled capacity of the convergent unification of readily accessible feedstock carboxylic acids and a chiral methyleneoxazolidinone fragment and the simultaneous highly diastereo-, chemo-, and regioselective incorporation of deuterium.

TL;DR: A direct cross-coupling between sodium sulfinates and 2H-indazoles has been developed under electrochemical conditions and should serve as a valuable synthetic tool to achieve heteroaromatic compounds.

TL;DR: The Co(III)-catalyzed redox-neutral annulation of benzamides and acrylamides with vinylene carbonate for the synthesis of isoquinolinones and pyridinones has been developed, affording the target products with good to excellent yields.

TL;DR: An electrochemical oxydihalogenation of alkynes has been developed for the first time and a variety of α,α-dihaloketones can be prepared with readily available CHCl3, CH2Cl2, ClCH2CH2Cl, and CH2Br2 as the halogen source under electrochemical conditions at room temperature.