15784-28-8Relevant academic research and scientific papers
Polymer supported Zn-salen complexes: An effective one-pot oxidative esterification of aldehydes to carboxylic esters
Balinge, Kamlesh Rudreshwar,Khiratkar, Avinash Ganesh,Bhagat, Pundlik Rambhau
, p. 1085 - 1095 (2017/08/08)
Polymer-supported Zn-salen (PS-Zn-salen) complexes were synthesized, characterized and used as a catalyst for one-pot oxidative esterification of aldehydes with alcohols. The PS-Zn-salen heterogeneous catalyst exhibited a high-performance for the oxidative esterification of aldehydes to the corresponding methyl/ethyl esters using hydrogen peroxide as a green oxidant. Due to the synergistic effect of polymer support, the heterogeneous catalyst presented superior catalytic activity and afford 100% conversion of 3,4,5-trimethoxybenzaldehyde and 4-chlorobenzaldehyde to corresponding esters under optimized conditions. The different alcohol substrates study (viz. methyl alcohol, ethyl alcohol, allyl alcohol and benzyl alcohol) showed reasonable selectivity for esters, indicating the scope of the catalysts. Significantly, the synthesized complexes possess good hydrophobic/heterogeneous properties, which permit facile reclamation of the catalyst by using mere filtration. Moreover, the effect of counter anions of complex also studied which indicated that there is no appreciable influence on the conversion of product. The catalyst was reused up to 5th successive run with the average conversion of ester 87.4%. Mechanistic studies have recognized that this “one pot” direct oxidative esterification proceeds through acid formation, proven by a GC–MS. The catalyst is also found to be very stable, up to 280?°C, confirmed by the thermo gravimetric study.
Safe Removal of the Allyl Protecting Groups of Allyl Esters using a Recyclable, Low-Leaching and Ligand-Free Palladium Nanoparticle Catalyst
Takagi, Koji,Fukuda, Hayato,Shuto, Satoshi,Otaka, Akira,Arisawa, Mitsuhiro
supporting information, p. 2119 - 2124 (2015/06/23)
A safe, facile and low-leaching (up to 0.04ppm) method has been developed for the removal of allyl, prenyl and benzyl protecting groups from the corresponding esters, using a sulfur-modified gold-supported palladium (SAPd) nanoparticle catalyst, which is known to be non-flammable. The catalyst itself was found to be recyclable and the reaction appeared to proceed on the surface of the SAPd.
Palladium-catalyzed allylic esterification via C-C bond cleavage of a secondary homoallyl alcohol
Wang, Yong,Kang, Qiang
supporting information, p. 4190 - 4193 (2014/10/15)
Palladium-catalyzed allylic esterifications of secondary homoallyl alcohols with acids via sequential retro-allylation and esterification are demonstrated, affording the corresponding allyl ester in up to 99% yield. The electron effect of the substituent of the secondary alcohol was found to be crucial to the selective C-C bond cleavage.
Irreversible catalytic ester hydrolysis of allyl esters to give acids and aldehydes by homogeneous ruthenium and ruthenium/palladium dual catalyst systems
Nakamura, Asami,Hamasaki, Akiyuki,Goto, Sachihiko,Utsunomiya, Masaru,Tokunaga, Makoto
supporting information; experimental part, p. 973 - 984 (2011/06/19)
An irreversible hydrolysis reaction of allyl esters (1) into carboxylic acids (2) and propanal (3) was achieved with a ruthenium/palladium (Ru/Pd) dual catalyst system. The optimized catalysts consists of a 1:1:1 mixture of (cyclopentadienyl)tris(acetonitrile)ruthenium hexafluorophosphate {[RuCp(MeCN)3] PF6}, bis(acetonitrile)palladium dichloride [PdCl2(MeCN)2] and 1,6-bis(diphenylphosphanyl)hexane (DPPHex). The reaction proceeds via isomerization of allyl esters to 1-propenyl esters and hydrolysis of them to give 2 and 3. The first isomerization step was virtually catalyzed by the Ru components and the second hydrolysis step was mainly catalyzed by the Pd components. The optimized bidentate phosphine (DPPHex) which has long alkylene chain effectively generates two vacant sites on the Ru centers by bridging coordination. When a chelating bidentate phosphine such as DPPE was employed, only one vacant site remained on the Ru center and resulted in a low activity. This chelating Ru complex of DPPE formed even in the presence of 2 equivalents of Ru or additional 1 equivalent of Pd. These differences in coordination behaviour between DPPHex and 1,2- bis(diphenylphosphanyl)ethane (DPPE) cause the differences of the catalytic activity in the first step. The phosphine coordination to Pd center slightly decreases the activity of second hydrolysis step but which was compensated by the increasing of the stability of Pd. On the whole, the optimized Ru/Pd dual catalyst system exhibited good performances on the irreversible hydrolysis of allyl esters.
Di-p-nitrobenzyl azodicarboxylate (DNAD): An alternative azo-reagent for the Mitsunobu reaction
Yang, Jianhai,Dai, Liyan,Wang, Xiaozhong,Chen, Yingqi
experimental part, p. 1456 - 1462 (2011/03/21)
Di-p-nitrobenzyl azodicarboxylate is prepared in 83.6% yield in two steps as a bright yellow solid, which can be used as an azo-reagent in the Mitsunobu reaction. When a chiral secondary alcohol was used, sufficient configurational inversion of alcohol occurred under Mitsunobu conditions. That the hydrazine produced from DNAD is semisoluble in some solvents such as THF and CH 2Cl2 makes it separated easily from the reaction mixture just via filtration. Then the recovered hydrazine compound can be re-exposed to oxidant to produce DNAD. Because DNAD is more stable than DIAD at ambient temperatures and allows easy separation, it is a good alternative azo-reagent for the Mitsunobu reaction.
The first general and selective palladium(II)-catalyzed alkoxycarbonylation of arylboronates: Interplay among benzoquinone-ligated palladium(0) complex, organoboron, and alcohol solvent
Yamamoto, Yoshihiko
supporting information; experimental part, p. 478 - 492 (2010/07/03)
Methoxycarbonylation of aryl- and alken-ylboron compounds was performed using the palladium (II) acetate/triphenylphosphine [PdACHTUNGTRENNUNG(OAc) 2/PPh3] catalyst with p-benzoquinone as a stoichiometric oxidant in methanol at ambient temperature to obtain the corresponding methyl esters in good yields. A wide variety of functional groups including various carbonyl functionalities, nitrile, nitro, sulfone, and unprotected pyrrole rings were tolerated in the methoxycarbonlation, while the use of higher alcohols except for tert-butanol afforded various pchlorobenzoates in moderate to high yields. The catalytic alkoxycarbonylation proceeded without any acid or base additive, and an oxidative transmetalation step is proposed to explain the exceptional efficacy of this protocol. DFT and MP2 calculations support the proposed mechanism.
Synthesis of para-substituted bicyclo[2.2.1]hept-5-en-2-ylmethyl benzoates
Mamedbeili,Kyazimova,Nagiev,Abdiev,Aliev
experimental part, p. 74 - 77 (2009/07/17)
para-Substituted bicyclo[2.2.1]hept-5-en-2-ylmethyl benzoates were synthesized by the Diels-Alder reaction of cyclopentadiene with the corresponding para-substituted allyl benzoates, and optimal reaction conditions were found. The product structure was confirmed by independent synthesis and IR and 1H NMR spectroscopy.
Protic acid immobilized on solid support as an extremely efficient recyclable catalyst system for a direct and atom economical esterification of carboxylic acids with alcohols
Chakraborti, Asit K.,Singh, Bavneet,Chankeshwara, Sunay V.,Patel, Alpesh R.
supporting information; experimental part, p. 5967 - 5974 (2009/12/24)
(Chemical Equation Presented) A convenient and clean procedure of esterification is reported by direct condensation of equimolar amounts of carboxylic acids with alcohols catalyzed by an easy to prepare catalyst system of perchloric acid immobilized on silica gel (HClO4-SiO2). The direct condensation of aryl, heteroaryl, styryl, aryl alkyl, alkyl, cycloalkyl, and long-chain aliphatic carboxylic acids with primary/secondary alkyl/cycloalkyl, allyl, propargyl, and long-chain aliphatic alcohols has been achieved to afford the corresponding esters in excellent yields. Chiral alcohol and N-t-Boc protected chiral amino acid also resulted in ester formation with the representative carboxylic acid or alcohol without competitive N-t-Boc deprotection and detrimental effect on the optical purity of the product demonstrating the mildness and chemoselectivity of the procedure. The esters of long-chain (>C10) acids and alcohols are obtained in high yields. The catalyst is recovered and recycled without significant loss of activity. The industrial application of the esterification process is demonstrated by the synthesis of prodrugs of ibuprofen and a few commercial flavoring agents. Other protic acids such as H2SO4, HBr, TfOH, HBF4, and TFA that were adsorbed on silica gel were less effective compared to HClO4-SiO2 following the order HClO4-SiO 2 ? H2SO4-SiO2 > HBr-SiO 2 > TfOH-SiO2 ? HBF4-SiO2 ≈ TFA-SiO2. When HClO4 was immobilized on other solid supports the catalytic efficiency followed the order HClO4-SiO 2 > HClO4-K10 > HClO4-Al 2O3 (neutral) > HClO4-Al2O 3 (acidic) > HClO4-Al2O3 (basic).
Synthesis and photostabilizing properties of hexachlorobicyclo[2.2.1]hept- 5-enylmethyl esters of substituted benzoic acids
Kyazimova,Mamedov,Babaev,Mamedova
, p. 438 - 442 (2008/09/20)
Polychlorinated bicyclic esters of p-substituted benzoic acids were prepared by the Diels-Alder reaction of hexachlorocyclopentadiene with allyl esters of p-substituted benzoic acids. Some of the adducts synthesized were tested as photostabilizers for polyethylene-based polymer formulations.
Surfactant-mediated solvent-free dealkylative cleavage of ethers and esters and trans-alkylation under neutral conditions
Bhattacharya, Apurba,Patel, Nitin C.,Vasques, Tomas,Tichkule, Ritesh,Parmar, Gaurang,Wu, Jiejun
, p. 565 - 567 (2007/10/03)
A simple, surfactant-mediated, one-pot, solvent-free dealkylative cleavage of aryl ethers and esters followed by subsequent optional trans-alkylation under essentially neutral conditions has been developed.
