1194-18-9Relevant articles and documents
A FACILE SYNTHESIS OF 1,3-CYCLOALKADIONES
Nishiguchi, Ikuzo,Hirashima, Tsuneaki,Shono, Tatsuya,Sasaki, Manji
, p. 551 - 554 (1981)
1,3-Cycloalkadiones were prepared by the reaction of 1,2-bis(trimethylsiloxy)cycloalkenes with chloromethyl methyl ether followed by treatment of the resulting 2-hydroxy-2-methoxymethyl cycloalkanones with potassium hydrogen sulfate.The first step of the reactions was effectively catalyzed by active zinc reagents prepared from zinc-copper and alkyl iodides.
Ambident Reactivity of Medium-Ring Cycloalkane-1,3-dione Enolates
Thompson, Glenn S.,Hirsch, Jerry A.
, p. 1098 - 1101 (1998)
Cycloalkane-1,3-diones with ring sizes 7-10 have been converted to their enolates and subjected to a variety of ethylation and methylation reagent/solvent systems. The greatest amount of O-alkylation was encountered using ethyl tosylate in HMPA. The O/C alkylation ratios decreased with almost every reagent/solvent system as the ring size was increased. This trend is consistent with greater steric strain in the conjugated enolate resonance contributor, resulting in diminished O-attack as the ring size is increased.
Maclean,Sneeden
, p. 31,34 (1965)
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.
Combined effects on selectivity in Fe-catalyzed methylene oxidation
Chen, Mark S.,White, M. Christina
scheme or table, p. 533 - 571 (2010/10/05)
Methylene C-H bonds are among the most difficult chemical bonds to selectively functionalize because of their abundance in organic structures and inertness to most chemical reagents. Their selective oxidations in biosynthetic pathways underscore the power of such reactions for streamlining the synthesis of molecules with complex oxygenation patterns. We report that an iron catalyst can achieve methylene C-H bond oxidations in diverse natural-product settings with predictable and high chemo-, site-, and even diastereoselectivities. Electronic, steric, and stereoelectronic factors, which individually promote selectivity with this catalyst, are demonstrated to be powerful control elements when operating in combination in complex molecules. This small-molecule catalyst displays site selectivities complementary to those attained through enzymatic catalysis.
Fragmentation of tertiary cyclopropanol compounds catalyzed by vanadyl acetylacetonate
Kirihara, Masayuki,Kakuda, Hiroko,Ichinose, Motohiro,Ochiai, Yuta,Takizawa, Shinobu,Mokuya, Asuka,Okubo, Kumiko,Hatano, Akihiko,Shiro, Motoo
, p. 4831 - 4839 (2007/10/03)
Tertiary cyclopropanol compounds react with a catalytic amount of vanadyl acetylacetonate in the presence of oxygen affording β-hydroxyketones and β-diketones. For 3-substituted-bicyclo[4.1.0]alkanols, peroxides are obtained, as are the β-hydroxyketones. Conversely, 2- ethoxycarbonylcyclopropyl silyl ethers produce ethyl γ-oxocarboxylate derivatives given the same reaction conditions.