5468-23-5Relevant academic research and scientific papers
Rh2(esp)2: An Efficient Catalyst for O-H Insertion Reactions of Carboxylic Acids into Acceptor/Acceptor Diazo Compounds
Hunter, Arianne C.,Chinthapally, Kiran,Sharma, Indrajeet
, p. 2260 - 2263 (2016)
Rh2(esp)2 has been identified as a highly efficient catalyst for O-H insertion of carboxylic acids into acceptor/acceptor diazo compounds. The insertion reaction proceeds in CH2Cl2 within minutes at room temperature in excellent yields and accommodates carboxylic acids having varying functionalities including amino acids, free alcoholic and phenolic O-H, indole N-H, alkenes, alkynes, and substituted aromatics. In addition, the reaction tolerates a broad range of stable diazo compounds carrying diverse functional groups. Diazo-Acid Insertion: A novel Rh2(esp)2-catalyzed O-H insertion reaction of carboxylic acids into acceptor/acceptor diazo compounds has been developed. The reaction is highly chemoselective and accommodates carboxylic acids having varying functionalities including amino acids, free alcoholic and phenolic O-H, indole N-H, alkenes, alkynes, and substituted aromatics.
Oxidation of Malonic Acid Derivatives by Manganese(III) Acetate. Aromatic Malonylation Reaction. Scope and Limitations
Citterio, Attilio,Santi, Roberto,Fiorani, Tiziana,Strologo, Sauro
, p. 2703 - 2712 (2007/10/02)
The oxidation of malonic acid derivatives RCH(COOR1)COOR2 (R1 = or R2 = H, Me, Et; R = H, Me, Et, n-Bu, i-Pr, C6H5, 4-OMeC6H4) by anhydrous or dihydrated manganese(III) acetate was studied in acetic acid in the presence of aromatic substrates at 20-80 deg C, generally with stoichiometric amounts of reagents.Electron-rich aromatics (IP 7.5 eV) underwent nuclear acetoxylation or quinone formation, the process being exclusive with anthracene and competitive with nuclear malonylation for 1- and 2-methoxynaphthalene.With other less electron-rich substrates (IP 8.5 eV) only the products coming from the oxidation of the malonic acid derivatives (aryl malonates, tartronates, etc., or dimerization and disproportionation products) were observed.The selectivity and the yield of aromatic substitution by the malonyl group was found to be affected by the electron density of the aromatic ring, the steric inhibition of substituents in the Mn(III) oxidation of the malonic acid derivative, the oxidizability of malonyl radical by Mn(III), the base (acetate ions or water) eventually present in the medium, and the further easy oxidation of the primary aryl malonate product, when unsubstituted dialkylmalonates or malonic acid were used.A mechanism is suggested in which inner-sphere electron transfer from Mn(III)-malonate complex affords Mn(II) malonyl radicals that are partitioned between oxidation, dimerization (or disproportionation), and reversible addition to the aromatics.
Reactions of Oxidizing Radicals with 4,6-Dihydroxypyrimidines as Model Compounds for Uracil, Thymine, and Cystosine
Novais, H. M.,Steenken, S.
, p. 426 - 433 (2007/10/02)
The reactions of the oxidizing radicals OH, O-, SO4-, and Br2- with 4,6-dihydroxypyrimidine (4,6-DHP) and with 2- and 5-methyl-4,6-DHP were investigated by using in situ radiolysis and photolysis ESR and pulse radiolysis techniques.In the pH range 1-6 the OH radical reacts with these compounds -1 s-1> selectively by addition at C-5 to produce radicals characterized by two pairs of magnetically equivalent nitrogens and exchangeable protons.On the basis of the coupling constants and from the increased pKa value (8.3) of the radical from 4,6-DHP relative to that (5.3) of the parent compound, a diketo-type structure is suggested for the OH adducts.At pH 8-12 a base-catalyzed dehydration of the radical anions takes place which leads to the formation of species formally derived from the ionized parent compound by one-electron oxidation followed by deprotonation.These radicals can also be produced by reaction with SO4- or Br2-.Those from 4,6-DHP and from 2-Me-4,6-DHP were seen in two different protonation states: as a neutral radical between pH 3 and 5, and as the radical anion above pH ca. 5.Methyl groups on the 4,6-DHP molecule increase the rate of dehydration of the OH adducts.The O- radical reacts with the methylated 4,6-DHP's by H abstraction from the methyl groups.The structures of all the radicals from the 4,6-DHP's are compared with those from naturally occuring dioxopyrimidines such as the uracils.
THE DEGRADATION OF CARBOXYLIC ACIDS INTO ALDEHYDES. REGIOSELECTIVE α-ACETOXYLATION OF 1,2,4-TRIAZOLIUM SALTS WITH DIACETOXYIODATE(1)ANION
Doleschall, Gabor,Toth, Gabor
, p. 1649 - 1666 (2007/10/02)
A novel method was developed for degradation of carboxylic acid into aldehydes containing one C atom less whose key step consists in α-acetoxylation of 5-alkyl-3-methylthio-1,4-diphenyl-1,2,4-triazolium iodides by (diacetoxyiodo)benzene.The mechanism of the regioselective α-acetoxylation was studied and the diacetoxy-iodate(1)anion was shown to be the actual oxidising agent.Further oxidation reactions of tetraethylammonium diacetoxyiodate(1) were investigated.A novel method was developed for the oxidation of primary alkyl amines into aldehydes by the novel heterocyclic reagent 5-bromo-3-methylthio-1,4-diphenyl-1,2,4-triazolium bromide and diethyl azodicarboxylate.
