Combined Photocatalysis and Lewis Acid Catalysis Strategy for the Oxa-Pictet–Spengler Reactions of Ethers

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(10), P. 7949 - 7955

Published: May 7, 2024

Saturated oxygen-containing heterocycles are present in numerous natural products and biologically active compounds. While the oxa-Pictet–Spengler reaction conventionally serves as a traditional synthetic strategy for preparing arene-fused tetrahydropyrans (THPs), existing methods typically involve harsh conditions. Disclosed herein is development of mild photocatalytically triggered ethers providing approach to fused THP The tuned dual photo/hydrogen-atom transfer (HAT) catalysis enables site- chemoselective C–H functionalization at benzylic ether, which results formation benzoate acetal intermediate. key intermediate then exposed subsequent Lewis acid catalysis, thus facilitating oxocarbenium ion generation ring closure. Notably, this combination successfully addresses concerns related overoxidation inherent photocatalytic systems.

Language: Английский

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Photoredox Activation of Fluorinated Organozinc Reagents: Hydrofluoroalkylation of Unactivated and Electron Deficient Alkenes

The Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 89(16), P. 11826 - 11835

Published: July 26, 2024

Hydrofluoroalkylation of alkenes with organozinc reagents under photocatalytic conditions is described. The fluorinated alkyl radicals were generated from organozincs by the single electron oxidation carbon-zinc bond. radical addition step followed either hydrogen atom transfer for unactivated olefins or a reduction/protonation sequence strongly accepting arylidenemalononitriles.

Language: Английский

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Photoredox/HAT-Catalyzed Intramolecular Hydrocyclization of Alkenes toward 2,3-Fused Quinazolinones and Dihydroquinazolinones

Organic Letters, Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 2, 2024

New photochemical approaches to 2,3-fused quinazolinones and dihydroquinazolinones are disclosed. The intramolecular hydrocyclization proceeds in moderate excellent yields across diverse alkenes with high regioselectivity diastereocontrol. Mechanistic studies indicated that the radical cascade processes involve thiophenol acting as single-electron transfer hydrogen atom reagents. success of gram-scale synthesis proves strategy can be used for practical applications.

Language: Английский

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Visible Light Mediated Difluoroalkylation of Alkenes Using Mercaptobenzothiazole‐Derived Sulfide Reagent

Advanced Synthesis & Catalysis, Journal Year: 2024, Volume and Issue: 366(24), P. 5171 - 5175

Published: Aug. 29, 2024

Abstract A method for the reductive difluoromethylation of alkenes with 2‐difluoromethylthio(benzothiazole) under photocatalytic conditions is described. The reaction involves generation difluoromethyl radical by means trimethyltriazinane, which serves as a precursor strongly reducing cyclic diaminoalkyl radical.

Language: Английский

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Building Catalytic Reactions One Electron at a Time

Accounts of Chemical Research, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 24, 2024

ConspectusClassical education in organic chemistry and catalysis, not the least my own, has centered on two-electron transformations, from nucleophilic attack to oxidative addition. The focus is well-founded, as this brand of enabled incredible feats synthesis, development life-saving pharmaceuticals production ubiquitous commodity chemicals. With that said, approach many ways complementary nature, where enzymes frequently make use single-electron "radical" steps achieve challenging reactions with exceptional selectivity, including light detection C-H hydroxylation. While power radical elementary undeniable, fundamental understanding of─and ability apply─these catalysis remains underdeveloped, constraining palette which chemists can new reactions.Motivation remedy traditional underemphasis been intensified by runaway success outer-sphere photoredox only confirming versatility radicals anthropogenic but also teaching value robust well-understood catalytic cycles for reaction design. Indeed, I would argue fueled strong its underlying steps, consideration transfer (SET) energetics allowing be designed

Language: Английский

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Functionalization of Boranes through Thiol/Oxygen Catalysis^†

Chinese Journal of Chemistry, Journal Year: 2024, Volume and Issue: 42(22), P. 2804 - 2810

Published: July 17, 2024

Comprehensive Summary A greener and more convenient alternative to traditional methods for the generation of thiyl radical as hydrogen atom transfer (HAT) catalyst is developed, using molecular oxygen oxidize thiol without need chemical initiators or light irradiation. The thiol/oxygen catalysis enables selective efficient difunctionalization borane.

Language: Английский

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