930-30-3Relevant articles and documents
Synthesis of functionalized olefins by cross and ring-closing metatheses [7]
Chatterjee, Arnab K.,Morgan, John P.,Scholl, Matthias,Grubbs, Robert H.
, p. 3783 - 3784 (2000)
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Independent generation of triplet 1,4-biradical intermediates implicated in the photochemical cycloaddition reaction between 2-cyclopentenone and acrylonitrile
Krug,Rudolph,Weedon
, p. 7221 - 7224 (1993)
Norrish Type 1 photochemistry of 3-cyanobicyclo[3.3.0]octane-2,6-dione and 3-cyanobicyclo[3.3.0]octane-2,8-dione is used to generate triplet 1,4-biradicals implicated in the photochemical cycloaddition reaction of 2-cyclopentenone with acrylonitrile. The fates of these biradicals have been determined and they suggest that the photocycloaddition reaction regiochemistry is governed by competition between closure of the biradicals to product and their reversion to ground state starting materials. This provides further evidence against the long-held view that the relative rates of formation of the biradicals mediated by an oriented triplet exciplex governs the reaction regiochemistry. It is also found that the regiochemistry of the photochemical cycloaddition reaction between cyclopentenone and acrylonitrile is reversed from that obtained in the addition of acrylonitrile to 2-cyclohexenone.
g-C3N4/metal halide perovskite composites as photocatalysts for singlet oxygen generation processes for the preparation of various oxidized synthons
Corti, Marco,Chiara, Rossella,Romani, Lidia,Mannucci, Barbara,Malavasi, Lorenzo,Quadrelli, Paolo
, p. 2292 - 2298 (2021/04/12)
g-C3N4/metal halide perovskite composites were prepared and used for the first time as photocatalysts forin situ1O2generation to perform hetero Diels-Alder, ene and oxidation reactions with suitable dienes and alkenes. The standardized methodology was made applicable to a variety of olefinic substrates. The scope of the method is finely illustrated and the reactions afforded desymmetrized hydroxy-ketone derivatives, unsaturated ketones and epoxides. Some limitations were also observed, especially in the case of the alkene oxidations, and poor chemoselectivity was somewhere observed in this work which is the first application of MHP-based composites forin situ1O2generation. The experimental protocol can be used as a platform to further expand the knowledge and applicability of MHPs to organic reactions, since perovskites offer a rich variety of tuning strategies which may be explored to improve reaction yields and selectivities.
Reductive Electrochemical Activation of Molecular Oxygen Catalyzed by an Iron-Tungstate Oxide Capsule: Reactivity Studies Consistent with Compound i Type Oxidants
Bugnola, Marco,Shen, Kaiji,Haviv, Eynat,Neumann, Ronny
, p. 4227 - 4237 (2020/05/05)
The reductive activation of molecular oxygen catalyzed by iron-based enzymes toward its use as an oxygen donor is paradigmatic for oxygen transfer reactions in nature. Mechanistic studies on these enzymes and related biomimetic coordination compounds designed to form reactive intermediates, almost invariably using various "shunt" pathways, have shown that high-valent Fe(V)=O and the formally isoelectronic Fe(IV) =O porphyrin cation radical intermediates are often thought to be the active species in alkane and arene hydroxylation and alkene epoxidation reactions. Although this four decade long research effort has yielded a massive amount of spectroscopic data, reactivity studies, and a detailed, but still incomplete, mechanistic understanding, the actual reductive activation of molecular oxygen coupled with efficient catalytic transformations has rarely been experimentally studied. Recently, we found that a completely inorganic iron-tungsten oxide capsule with a keplerate structure, noted as {Fe30W72}, is an effective electrocatalyst for the cathodic activation of molecular oxygen in water leading to the oxidation of light alkanes and alkenes. The present report deals with extensive reactivity studies of these {Fe30W72} electrocatalytic reactions showing (1) arene hydroxylation including kinetic isotope effects and migration of the ipso substituent to the adjacent carbon atom ("NIH shift"); (2) a high kinetic isotope effect for alkyl C - H bond activation; (3) dealkylation of alkylamines and alkylsulfides; (4) desaturation reactions; (5) retention of stereochemistry in cis-alkene epoxidation; and (6) unusual regioselectivity in the oxidation of cyclic and acyclic ketones, alcohols, and carboxylic acids where reactivity is not correlated to the bond disassociation energy; the regioselectivity obtained is attributable to polar effects and/or entropic contributions. Collectively these results also support the conclusion that the active intermediate species formed in the catalytic cycle is consistent with a compound I type oxidant. The activity of {Fe30W72} in cathodic aerobic oxidation reactions shows it to be an inorganic functional analogue of iron-based monooxygenases.