Addition Reactions: Cycloaddition DOI

N. Dennis

Organic Reaction Mechanisms/Organic reaction mechanisms, Journal Year: 2023, Volume and Issue: unknown, P. 473 - 517

Published: Jan. 20, 2023

This chapter presents an extensive review detailing the formal cycloadditions of allenes and allenamides, catalysed by gold palladium catalysts. It is proposed that free radical intermediate attacks C—C double bond naphthoquinone, leading to formation of, which, upon loss a sulfate anion, gives cyclobutene. The mechanism involves ruthenacyclopentene, generated ene–yne oxidative cyclization, which undergoes sequential β-hydride elimination intramolecular hydroruthenation form ruthenacyclohexene. Tetraarylphosphonium salts catalyse 3+2-cycloaddition glycidol isocyanates produce 4-hydroxymethyl-substituted oxazolidinones including enantioenriched ones. Lewis acid-promoted carbonyl imine intermediates with cyclic allylic alcohols produced bicyclic isoxazolidine cycloadducts in good-to-high yields. Tetrasubstituted bulkier trisubstituted allyl nitrones failed provide respective highly substituted chromenoisoxazolidines.

Language: Английский

Ruthenium-Catalyzed Cycloadditions to Form Five-, Six-, and Seven-Membered Rings DOI
Rosalie S. Doerksen, Tomáš Hodík, Guanyu Hu

et al.

Chemical Reviews, Journal Year: 2021, Volume and Issue: 121(7), P. 4045 - 4083

Published: Feb. 12, 2021

Ruthenium-catalyzed cycloadditions to form five-, six-, and seven-membered rings are summarized, including applications in natural product total synthesis. Content is organized by ring size reaction type. Coverage limited processes that involve formation of at least one C–C bond. Processes stoichiometric ruthenium or exploit as a Lewis acid (without intervention organometallic intermediates), formations occur through dehydrogenative condensation-reduction, σ-bond activation-initiated annulations do not result net reduction bond multiplicity, photochemically promoted ruthenium-catalyzed covered.

Language: Английский

Citations

58
Visible-Light Mediated Diarylselenylative Cyclization of 1,6-Enynes DOI
Hong Hou, Yue Sun,

Yingjie Pan

et al.

The Journal of Organic Chemistry, Journal Year: 2020, Volume and Issue: 86(1), P. 1273 - 1280

Published: Dec. 7, 2020

We herein described a selenylative cyclization reaction of enynes by the utilization diselenides as radical sources. The visible-light irradiation mixture enables generation selenium atom to trigger addition/cyclization/selenation sequences. Both terminal alkyne and internal derived 1,6-enynes were tested suitable for current synthetic protocol, delivering various kinds selenium-containing cycles in good yields.

Language: Английский

Citations

37
Propargylic Dialkyl Effect for Cyclobutene Formation through Ir(III)-Catalyzed Cycloisomerization of 1,6-Enynes DOI

Xuanyu Zhu,

Yi Li,

Hongtao Luo

et al.

Organic Letters, Journal Year: 2024, Volume and Issue: 26(4), P. 966 - 970

Published: Jan. 25, 2024

The propargylic dialkyl effect (PDAE) has a significant impact on the cyclization reaction of enynes, partly reflected in changing types products. Herein, we described influence Ir(III)-catalyzed cycloisomerization 1,6-enynes to provide strained cyclobutenes. A series substituted were proved be excellent substrate candidates presence [Cp*IrCl2]2 toluene. Mechanistic investigation, based deuterium labeling experiments and control experiments, indicated that might boost C(sp)-H activation by preventing coordination active iridium species C(sp)≡C(sp) bond enynes. This finding contributes fundamental understanding enyne reactions offers valuable insight into effect.

Language: Английский

Citations

1
Oxidation and Reduction DOI

R. N. Mehrotra

Organic Reaction Mechanisms/Organic reaction mechanisms, Journal Year: 2023, Volume and Issue: unknown, P. 65 - 140

Published: Jan. 20, 2023

A total of 24 reviews including 6 mini and 4 accounts are published in 2019. The first the describes processing polysaccharides, particularly recalcitrant insoluble such as cellulose lignocellulosic biomass, by lytic polysaccharide monooxygenases (LPMOs), a monocopper enzyme. LPMO reactions driven both molecular oxygen hydrogen peroxide. application an azo-phenolate ligand-coordinated nickel catalyst N-alkylation variety anilines alcohols is reported. redox-active azo ligand stores generated during alcohol oxidation redelivers it to situ imine leading amine. simple efficient protocol for regioselective indoles 2-oxindoles using sulfuric acid adsorbed on silica gel reagent reaction has broad substrate scope functional group tolerance.

Language: Английский

Citations

0
Addition Reactions: Cycloaddition DOI

N. Dennis

Organic Reaction Mechanisms/Organic reaction mechanisms, Journal Year: 2023, Volume and Issue: unknown, P. 473 - 517

Published: Jan. 20, 2023

This chapter presents an extensive review detailing the formal cycloadditions of allenes and allenamides, catalysed by gold palladium catalysts. It is proposed that free radical intermediate attacks C—C double bond naphthoquinone, leading to formation of, which, upon loss a sulfate anion, gives cyclobutene. The mechanism involves ruthenacyclopentene, generated ene–yne oxidative cyclization, which undergoes sequential β-hydride elimination intramolecular hydroruthenation form ruthenacyclohexene. Tetraarylphosphonium salts catalyse 3+2-cycloaddition glycidol isocyanates produce 4-hydroxymethyl-substituted oxazolidinones including enantioenriched ones. Lewis acid-promoted carbonyl imine intermediates with cyclic allylic alcohols produced bicyclic isoxazolidine cycloadducts in good-to-high yields. Tetrasubstituted bulkier trisubstituted allyl nitrones failed provide respective highly substituted chromenoisoxazolidines.

Language: Английский

Citations

0