Photocatalytic decarboxylative alkylations mediated by triphenylphosphine and sodium iodide

Science, Год журнала: 2019, Номер 363(6434), С. 1429 - 1434

Опубликована: Март 28, 2019

Most photoredox catalysts in current use are precious metal complexes or synthetically elaborate organic dyes, the cost of which can impede their application for large-scale industrial processes. We found that a combination triphenylphosphine and sodium iodide under 456-nanometer irradiation by blue light-emitting diodes catalyze alkylation silyl enol ethers decarboxylative coupling with redox-active esters absence transition metals. Deaminative using Katritzky's N-alkylpyridinium salts trifluoromethylation Togni's reagent also demonstrated. Moreover, phosphine/iodide-based system catalyzes Minisci-type N-heterocycles operate tandem chiral phosphoric acids to achieve high enantioselectivity this reaction.

Язык: Английский

---

Photoinduced Deaminative Borylation of Alkylamines

Journal of the American Chemical Society, Год журнала: 2018, Номер 140(34), С. 10700 - 10704

Опубликована: Авг. 9, 2018

An operationally simple deaminative borylation reaction of primary alkylamines has been developed. The formation electron-donor-acceptor complexes between N-alkylpyridinium salts and bis(catecholato)diboron enables photoinduced single-electron transfer fragmentation to carbon-centered radicals, which are subsequently borylated. mild conditions allow a diverse range readily available be efficiently converted into synthetically valuable alkylboronic esters under catalyst-free conditions.

Язык: Английский

---

Photoinduced Borylation for the Synthesis of Organoboron Compounds

Chemical Reviews, Год журнала: 2021, Номер 121(7), С. 3561 - 3597

Опубликована: Фев. 17, 2021

Organoboron compounds have important synthetic value and can be applied in numerous transformations. The development of practical convenient ways to synthesize boronate esters has thus attracted significant interest. Photoinduced borylations originated from stoichiometric reactions alkanes arenes with well-defined metal–boryl complexes. Now, photoredox-initiated borylations, catalyzed by either transition metal or organic photocatalysts, photochemical high efficiency become a burgeoning area research. In this Focus Review, we summarize research on photoinduced especially emphasizing recent developments trends. This includes the borylation arenes, alkanes, aryl/alkyl halides, activated carboxylic acids, amines, alcohols, so based catalysis, metal-free organocatalysis, direct activation. We focus reaction mechanisms involving single-electron transfer, triplet-energy other radical processes.

Язык: Английский

---

Nitrogen-Centered Radicals in Functionalization of sp² Systems: Generation, Reactivity, and Applications in Synthesis

Chemical Reviews, Год журнала: 2022, Номер 122(9), С. 8181 - 8260

Опубликована: Март 14, 2022

The chemistry of nitrogen-centered radicals (NCRs) has plentiful applications in organic synthesis, and they continue to expand as our understanding these reactive species increases. utility intermediates is demonstrated the recent advances C–H amination (di)amination alkenes. Synthesis previously challenging structures can be achieved by efficient functionalization sp2 moieties without prefunctionalization, allowing for faster more streamlined synthesis. This Review addresses generation, reactivity, application NCRs, including, but not limited to, iminyl, aminyl, amidyl, aminium species. Contributions from early discovery up most examples have been highlighted, covering radical initiation, thermolysis, photolysis, and, recently, photoredox catalysis. Radical-mediated intermolecular (hetero)arenes occur with a variety complex amine precursors, generating aniline derivatives, an important class drug development. Functionalization olefins achievable high anti-Markovnikov regioselectivity allows access difunctionalized when intermediate carbon are trapped. Additionally, reactivity NCRs harnessed rapid construction N-heterocycles such pyrrolidines, phenanthridines, quinoxalines, quinazolinones.

Язык: Английский

---

Deaminative Borylation of Aliphatic Amines Enabled by Visible Light Excitation of an Electron Donor–Acceptor Complex

Chemistry - A European Journal, Год журнала: 2018, Номер 24(65), С. 17210 - 17214

Опубликована: Окт. 6, 2018

Abstract A deaminative strategy for the borylation of aliphatic primary amines is described. Alkyl radicals derived from single‐electron reduction redox‐active pyridinium salts, which can be isolated or generated in situ, were borylated a visible light‐mediated reaction with bis(catecholato)diboron. No catalyst further additives required. The key electron donor–acceptor complex was characterized detail by both experimental and computational investigations. synthetic potential this mild protocol demonstrated through late‐stage functionalization natural products drug molecules.

Язык: Английский

---

Cooperative NHC and Photoredox Catalysis for the Synthesis of β‐Trifluoromethylated Alkyl Aryl Ketones

Angewandte Chemie International Edition, Год журнала: 2020, Номер 59(45), С. 19956 - 19960

Опубликована: Июль 23, 2020

Despite the great potential of radical chemistry in organic synthesis, N-heterocyclic carbene (NHC)-catalyzed reactions involving intermediates are not well explored. This communication reports three-component coupling aroyl fluorides, styrenes and Langlois reagent (CF3 SO2 Na) to give various β-trifluoromethylated alkyl aryl ketones with good functional group tolerance moderate high yields by cooperative photoredox/NHC catalysis. The alkene acyltrifluoromethylation proceeds via radical/radical cross ketyl radicals benzylic C-radicals. generated SET reduction situ formed acylazolium ions whereas derive from trifluoromethyl addition onto styrenes.

Язык: Английский

---

Metal-free photoinduced C(sp3)–H borylation of alkanes

Nature, Год журнала: 2020, Номер 586(7831), С. 714 - 719

Опубликована: Окт. 28, 2020

Язык: Английский

---

Selective C−N Borylation of Alkyl Amines Promoted by Lewis Base

Angewandte Chemie International Edition, Год журнала: 2018, Номер 57(46), С. 15227 - 15231

Опубликована: Сен. 25, 2018

An efficient method for the metal-free deaminative borylation of alkylamines, using bis(catecholato)diboron as boron source, to directly synthesize various alkyl potassium trifluoroborate salts is introduced. The key this high reactivity utilization pyridinium salt activated with a catalytic amount bipyridine-type Lewis base promoter. This transformation shows good functional-group compatibility (e.g., it unimpeded by presence ketone, indole, internal alkene, or unactivated chloride) and can serve powerful synthetic tool amine groups in complex compounds. Mechanistic experiments computations suggest mechanism which B2 cat2 unit intercepts an radical generated single-electron transfer (SET) from boron-based reductant.

Язык: Английский

---

Desulfonylation via Radical Process: Recent Developments in Organic Synthesis

Chemical Reviews, Год журнала: 2021, Номер 121(20), С. 12548 - 12680

Опубликована: Авг. 13, 2021

As the "chemical chameleon", sulfonyl-containing compounds and their variants have been merged with various types of reactions for efficient construction diverse molecular architectures by taking advantage incredible reactive flexibility. Currently, involvement in radical transformations, which sulfonyl group typically acts as a leaving via selective C–S, N–S, O–S, S–S, Se–S bond cleavage/functionalization, has facilitated new formation strategies are complementary to classical two-electron cross-couplings organometallic or ionic intermediates. Considering great influence synthetic potential these novel avenues, we summarize recent advances this rapidly expanding area discussing reaction designs, substrate scopes, mechanistic studies, limitations, outlining state-of-the-art processes involved radical-mediated desulfonylation related transformations. With specific emphasis on applications, believe review will be useful medicinal organic chemists who interested chemistry particular.

Язык: Английский

---

Metal‐Free Radical Borylation of Alkyl and Aryl Iodides

Angewandte Chemie International Edition, Год журнала: 2018, Номер 57(51), С. 16832 - 16836

Опубликована: Окт. 17, 2018

Abstract A metal‐free radical borylation of alkyl and aryl iodides with bis(catecholato)diboron (B 2 cat ) as the boron source under mild conditions is introduced. The reaction operationally easy to conduct shows high functional group tolerance broad substrate scope. Radical clock experiments density theory calculations provide insights into mechanism rate constants for C‐radical B are disclosed.

Язык: Английский

---