- From 2-thienylcopper couplings to trimethylsilyl-promoted organocopper additions
-
In this paper we continue a 2-thienylcopper line started about twenty years ago with the cross-coupling with iodobenzenes in quinoline.We now report a preparative and NMR study of the favourable influence of trimethylchlorosilane on the conjugate addition
- Lindstedt, Eva-Lotte,Nilsson, Martin,Olsson, Thomas
-
-
Read Online
- An umpolung-enabled copper-catalysed regioselective hydroamination approach to α-amino acids
-
A copper-catalysed regio- and stereoselective hydroamination of acrylates with hydrosilanes and hydroxylamines has been developed to afford the corresponding α-amino acids in good yields. The key to regioselectivity control is the use of hydroxylamine as
- Hirano, Koji,Miura, Masahiro,Nishino, Soshi
-
p. 11525 - 11537
(2021/09/07)
-
- Harnessing Applied Potential: Selective β-Hydrocarboxylation of Substituted Olefins
-
The construction of carboxylic acid compounds in a selective fashion from low value materials such as alkenes remains a long-standing challenge to synthetic chemists. In particular, β-addition to styrenes is underdeveloped. Herein we report a new electrosynthetic approach to the selective hydrocarboxylation of alkenes that overcomes the limitations of current transition metal and photochemical approaches. The reported method allows unprecedented direct access to carboxylic acids derived from β,β-trisubstituted alkenes, in a highly regioselective manner.
- Alkayal, Anas,Buckley, Benjamin R.,Malkov, Andrei V.,Montanaro, Stephanie,Tabas, Volodymyr,Wright, Iain A.
-
supporting information
(2020/02/13)
-
- Asymmetric Umpolung Hydrogenation and Deuteration of Alkenes Catalyzed by Nickel
-
Nickel-catalyzed asymmetric hydrogenation of several types of alkenes proceeds in high enantioselectivity, using acetic acid or water as the hydrogen source and indium powder as electron donor. The scope of alkenes herein include α,β-unsaturated esters, n
- Guo, Siyu,Wang, Xiuhua,Zhou, Jianrong Steve
-
supporting information
p. 1204 - 1207
(2020/02/04)
-
- Iridium-Catalyzed Alkene-Selective Transfer Hydrogenation with 1,4-Dioxane as Hydrogen Donor
-
The iridium-catalyzed transfer hydrogenation of alkenes using 1,4-dioxane as a hydrogen donor is described. The use of 1,2-bis(dicyclohexylphosphino)ethane (DCyPE), featuring bulky and highly electron-donating properties, led to high catalytic activity. A polystyrene-cross-linking bisphosphine PS-DPPBz produced a reusable heterogeneous catalyst. These homogeneous and heterogeneous protocols achieved chemoselective transfer hydrogenation of alkenes over other potentially reducible functional groups such as carbonyl, nitro, cyano, and imino groups in the same molecule.
- Zhang, Deliang,Iwai, Tomohiro,Sawamura, Masaya
-
supporting information
p. 5867 - 5872
(2019/08/26)
-
- Development of alkyl glycerone phosphate synthase inhibitors: Structure-activity relationship and effects on ether lipids and epithelial-mesenchymal transition in cancer cells
-
In aggressive tumors, alkylglyceronephosphate synthase (AGPS) controls cellular ether phospholipid utilization and metabolism to promote cancer cell proliferation and motility. SAR studies on the first-in-class AGPS inhibitor 1, discovered by our group, led to the 2,6-difluoro analog 2i which showed higher binding affinity than 1 in vitro. In 231MFP cancer cells, 2i reduced ether lipids levels and cell migration rate. When tested in PC-3 and MDA-MB-231 cancer cells, 2i specifically impaired epithelial to mesenchymal transition (EMT) by modulating E-cadherin, Snail and MMP2 expression levels. Moreover, the combination of siRNAs against AGPS and 2i provided no additive effect, confirming that the modulation of 2i on EMT specifically relies on AGPS inhibition. Finally, this compound also affected cancer cell proliferation especially in MDA-MB-231 cells expressing higher AGPS level, whereas it provided negligible effects on MeT5A, a non-tumorigenic cell line, thus showing cancer specificity.
- Stazi, Giulia,Battistelli, Cecilia,Piano, Valentina,Mazzone, Roberta,Marrocco, Biagina,Marchese, Sara,Louie, Sharon M.,Zwergel, Clemens,Antonini, Lorenzo,Patsilinakos, Alexandros,Ragno, Rino,Viviano, Monica,Sbardella, Gianluca,Ciogli, Alessia,Fabrizi, Giancarlo,Cirilli, Roberto,Strippoli, Raffaele,Marchetti, Alessandra,Tripodi, Marco,Nomura, Daniel K.,Mattevi, Andrea,Mai, Antonello,Valente, Sergio
-
p. 722 - 735
(2019/01/04)
-
- Alkoxycarbonylation of olefins with carbon dioxide by a reusable heterobimetallic ruthenium-cobalt catalytic system
-
The heterobimetallic ruthenium-cobalt catalytic system exhibited good catalytic performance and reusability in the reductive alkoxycarbonylation of olefins with carbon dioxide. Compared to the previous system only consisting of ruthenium catalyst, the binary catalyst system effectively reduced the usage of noble metal and ionic liquid additives. The respective contribution of ruthenium and cobalt catalysts in this multiple-step catalytic process was investigated by a series of condition-controlled experiments. The evolution of the ruthenium catalyst and the occurrence of alkene hydrogenation during the reaction was explained by theortical calculations.
- Zhang, Xuehua,Shen, Chaoren,Xia, Chungu,Tian, Xinxin,He, Lin
-
supporting information
p. 5533 - 5539
(2019/01/03)
-
- Development of efficient palladium catalysts for alkoxycarbonylation of alkenes
-
Herein, we report a general and efficient Pd-catalysed alkoxycarbonylation of sterically hindered and demanding olefins including a variety of tri-, tetra-substituted and 1,1-disubstituted alkenes. In the presence of 1,3-bis(tert-butyl(pyridin-2-yl)phosphanyl)propane L3 or 1,4-bis(tert-butyl(pyridin-2-yl)phosphanyl)butane L4 the desired esters are obtained in good yields and selectivities. Similar transformation is obtained using tertiary ether as showcased in the carbonylation of MTBE to the corresponding linear ester in high yield and selectivity.
- Liu, Jiawang,Dong, Kaiwu,Franke, Robert,Neumann, Helfried,Jackstell, Ralf,Beller, Matthias
-
supporting information
p. 12238 - 12241
(2018/11/21)
-
- Palladium-Catalyzed Carbonylation of sec- and tert-Alcohols
-
A general palladium-catalyzed synthesis of linear esters directly from sec- and tert-alcohols is described. Compared to the classic Koch–Haaf reaction, which leads to branched products, this new transformation gives the corresponding linear esters in high yields and selectivity. Key for this protocol is the use of an advanced palladium catalyst system with L2 (pytbpx) as the ligand. A variety of aliphatic and benzylic alcohols can be directly used and the catalyst efficiency for the benchmark reaction is outstanding (turnover number up to 89 000).
- Dong, Kaiwu,Sang, Rui,Liu, Jie,Razzaq, Rauf,Franke, Robert,Jackstell, Ralf,Beller, Matthias
-
supporting information
p. 6203 - 6207
(2017/05/22)
-
- Benzene-based diphosphine ligands for alkoxycarbonylation
-
The invention relates to benzene-based diphosphine ligands for alkoxycarbonylation. Specifically, the invention relates to compounds of formula (I), where m and n are each independently 0 or 1; R1, R2, R3, R4 are each independently selected from -(C1-C12)-alkyl, -(C3-C12)-cycloalkyl, -(C3-C12)-heterocycloalkyl, -(C6-C20)-aryl, -(C3-C20)-heteroaryl; at least one of the R1, R2, R3, R4 radicals is a -(C3-C20)-heteroaryl radical; and to the use thereof as ligands in alkoxycarbonylation.
- -
-
Paragraph 0180; 0181; 0184
(2017/02/28)
-
- Multicomponent reaction comprising one-pot installation of bidentate directing group and Pd(II)-catalyzed direct β-arylation of C(sp3)[sbnd]H bond of aliphatic and alicyclic carboxamides
-
In this paper, we report a step-economical one-pot multicomponent reaction protocol comprising the installation of the bidentate directing group (auxiliary) followed by Pd(II)-catalyzed sp3C[sbnd]H activation and β-arylation of various aliphatic/alicyclic carboxamides. Accordingly, the reaction of a mixture of an aliphatic/alicyclic acid chloride, bidentate directing auxiliary (e.g., 8-aminoquinoline) and an aryl iodide in the presence of the Pd(OAc)2catalyst and Ag2CO3additive directly afforded the corresponding β-C[sbnd]H-arylated N-(quinolin-8-yl)carboxamide derivative. To demonstrate the efficiency of the process, various bidentate directing auxiliaries were used and 8-Aminoquinoline was found to be the best directing group for accomplishing the one-pot Pd(II)-catalyzed, sp3C[sbnd]H activation and β-arylation of aliphatic/alicyclic carboxamides. A variety of aliphatic/alicyclic acid chlorides and aryl iodides were used as the substrates and several β-C[sbnd]H arylated carboxamide derivatives were synthesized in moderate to high yields via the multicomponent reaction strategy.
- Mohan, Sruthi,Gopalakrishnan, Bojan,Babu, Srinivasarao Arulananda
-
p. 5853 - 5863
(2016/09/07)
-
- ANTI-HCMV COMPOSITIONS AND METHODS
-
This document relates to compounds useful as agents for preventing or treating human cytomegalovirus (HCMV) infections.
- -
-
Page/Page column 35
(2016/06/06)
-
- N,N-Dimethylformamide as Hydride Source in Nickel-Catalyzed Asymmetric Hydrogenation of α,β-Unsaturated Esters
-
Asymmetric transfer hydrogenation of α,β-unsaturated esters is realized by using a nickel/bisphosphine catalyst and N,N-dimethylformamide (DMF) as the hydride source.
- Guo, Siyu,Zhou, Jianrong
-
supporting information
p. 5344 - 5347
(2016/11/02)
-
- Parameters Influencing Reactivity and Regioselectivity in the Methoxycarbonylation of Arylalkenes
-
Previous research showed that the steric bulk, electronic character, and bite angle of the ligand have an influence on both the catalyst activity and regioselectivity of hydroformylation and hydroesterification reactions. However, little is known in this regard about the influence of the steric and electronic environment around the double bond of the substrate. A variety of arylalkenes were therefore subjected to methoxycarbonylation to investigate the steric and electronic effects of substituents on the aromatic ring of the substrate on the regioselectivity and reactivity in the methoxycarbonylation reaction of these substrates with a Pd(II)/Al(OTf)3/Ph3P catalyst system.
- Du Plessis, Maretha,Marais, Charlene,Bezuidenhoudt, Barend C. B.
-
p. 557 - 565
(2016/02/14)
-
- Nickel-catalyzed asymmetric transfer hydrogenation of conjugated olefins
-
Asymmetric transfer hydrogenation of electron-deficient olefins is realized with nickel catalysts supported by strongly σ-donating bisphosphines. Deuterium labeling experiments point to a reaction sequence of formate decarboxylation, asymmetric hydride in
- Guo, Siyu,Yang, Peng,Zhou, Jianrong
-
supporting information
p. 12115 - 12117
(2015/07/28)
-
- Regioselective Pd-Catalyzed Methoxycarbonylation of Alkenes Using both Paraformaldehyde and Methanol as CO Surrogates
-
In recent years, considerable effort has focused on the development of novel carbonylative transformations using CO surrogates. Consequently, toxic CO gas can be replaced by more convenient inorganic or organic carbonyl compounds. Herein, the first regioselective methoxycarbonylation of alkenes with paraformaldehyde and methanol as CO substitutes is reported. This new procedure is applicable to a series of alkenes in the presence of a palladium catalyst under relatively mild conditions and is highly atom efficient.
- Liu, Qiang,Yuan, Kedong,Arockiam, Percia-Beatrice,Franke, Robert,Doucet, Henri,Jackstell, Ralf,Beller, Matthias
-
supporting information
p. 4493 - 4497
(2015/04/14)
-
- A recyclable CO surrogate in regioselective alkoxycarbonylation of alkenes: Indirect use of carbon dioxide
-
Herein, we report a Pd-catalysed alkoxycarbonylation of alkenes based on the use of a recyclable CO2 reduction product, the crystalline and air-stable N-formylsaccharin, as a CO surrogate. The carbonylation proceeds under ambient conditions in an exceptionally complementary regioselective fashion yielding the desired branched products from styrene derivatives and valuable linear esters from alkyl-substituted alkenes.
- Gehrtz,Hirschbeck,Fleischer
-
supporting information
p. 12574 - 12577
(2015/08/06)
-
- Gallium-assisted transfer hydrogenation of alkenes
-
We report a rare case of alkene transfer hydrogenation using a main-group compound instead of a transition-metal complex as catalyst. We disclosed that 1, 4-cyclo-hexadiene can be used as H2 surrogate towards olefin reduction in the presence of [IPrGaCl2][SbF6]. Hydrogenative cycli-zations have also been carried out because this cationic gallium complex is also a potent hydroarylation catalyst.
- Michelet, Bastien,Bour, Christophe,Gandon, Vincent
-
supporting information
p. 14488 - 14492
(2015/04/16)
-
- Hydroesterification of styrene derivatives catalyzed by an acidic resin supporting palladium complexes
-
Pd-TPPTS-OTPPTS (denoted as Pd-P-OP, where TPPTS was the sodium salt of tri(m-sulfophenyl)phosphine and OTPPTS was the oxidized form of TPPTS) complexes supported on acidic resins (denoted as Pd-P-OP/resin) were prepared and employed as versatile heterogeneous catalysts for the hydroesterification of vinyl-aromatics with alcohols. The catalysts were characterized by the methods of FT-IR, XPS, N2 physisorption, XRD, TGA, SEM and 31P NMR. According to the 31P NMR results, there was a weak coordination between OTPPTS and the Pd sites. Consequently, OTPPTS was a weak ligand to the Pd sites and thus dissociated easily, acting as a protective agent of the vacant coordination site of the Pd metal sites, which allowed the substrates more access to the metal sites. In the hydroesterification of styrene, the distribution of the branched and linear esters was remarkably impacted by adding an appropriate amount of OTPPTS and the acidic resin supports. A high yield and excellent selectivity towards the branched ester were obtained when OTPPTS and TPPTS were used in equimolar amounts under optimized reaction conditions. The generality and recyclability of the catalyst for the hydroesterification of vinyl-aromatics were also examined. In addition, the poisoning and hot filtration tests indicated that Pd(0) acted as the active species in a truly heterogeneous way. A Pd-hydride mechanism was proposed for the hydroesterification over the Pd-P-OP/LSI-600 catalyst. This journal is the Partner Organisations 2014.
- He, Zhenhong,Hou, Zhenshan,Luo, Yanping,Dilixiati, Yierxiati,Eli, Wumanjiang
-
p. 1092 - 1103
(2014/04/03)
-
- Methoxycarbonylation of olefins catalyzed by palladium(II) complexes containing naphthyl(diphenyl)phosphine ligands
-
Palladium(II) complexes containing phosphine donor ligands derived from naphthyl(diphenyl)phosphine were synthesized and characterized by NMR and elemental analysis. The complexes were studied as catalyst precursors in the methoxycarbonylation reaction of several aromatic and aliphatic olefins under mild conditions. The catalysts reported high chemoselectivities (over 96%) and regioselectivities between 44% and 93% for different olefins. The best results were obtained over a styrene substrate with 97% of conversion after 6 h of reaction, with high regioselectivity (93%). Kinetic studies permitted the determination of the rate law (v-‰=-‰k [substrate] 1.21±0.02 [catalyst]0.94±0.11 [acid] 0.52±0.03 [MeOH]0.53±0.05 [CO] 0.65±0.03) for methoxycarbonylation of styrene.
- Zolezzi, Santiago,Moya, Sergio A.,Valdebenito, Gonzalo,Abarca, Gabriel,Parada, Jose,Aguirre, Pedro
-
p. 364 - 371
(2014/05/06)
-
- Natural diversity to guide focused directed evolution
-
Simultaneous multiple site-saturation mutagenesis was performed at four active-site positions of an esterase from Pseudomonas fluorescens to improve its ability to convert 3-phenylbutyric acid esters (3-PBA) in an enantioselective manner. Based on an appropriate codon choice derived from a structural alignment of 1751 sequences of α/β-hydrolase fold enzymes, only those amino acids were considered for library creation that appeared frequently in structurally equivalent positions. Thus, the number of mutants to be screened could be substantially reduced while the number of functionally intact variants was increased. Whereas the wild-type esterase showed only marginal activity and poor enantioselectivity (Etrue=3.2) towards 3-PBA-ethyl ester, a significant number of hits with improved rates (up to 240-fold) and enantioselectivities (up to Etrue=80) were identified in these "smart" libraries.
- Jochens, Helge,Bornscheuer, Uwe T.
-
experimental part
p. 1861 - 1866
(2011/11/29)
-
- Indium-catalyzed coupling reaction between silyl enolates and alkyl chlorides or alkyl ethers
-
The coupling reactions of alkyl chlorides with silyl enolates catalyzed by InBr3, and the coupling reactions of alkyl ethers with silyl enolates catalyzed by the combined Lewis acid of InBr3/Me3SiBr are described. In both reaction systems, various types of silyl enolates were used to give corresponding α-alkylated esters, ketones, carboxylic acids, amides, thioesters, and aldehydes.
- Nishimoto, Yoshihiro,Saito, Takahiro,Yasuda, Makoto,Baba, Akio
-
experimental part
p. 5462 - 5471
(2009/12/01)
-
- Rhodium-catalyzed conjugate addition of Sb-aryl-1,5-azastibocines to α,β-unsaturated carbonyl compounds
-
Rhodium-catalyzed conjugate addition of Sb-aryl-1,5-azastibocines to α,β-unsaturated carbonyl compounds is described. The rhodium-catalyzed reaction was carried out in aqueous N-methy-2-pyrrolidinone (NMP) to give 1,4-conjugate adduct exclusively, while t
- Kakusawa, Naoki,Yasuike, Shuji,Kurita, Jyoji
-
experimental part
p. 1269 - 1283
(2010/10/03)
-
- Addition reaction of arylboronic acids to aldehydes and α,β-unsaturated carbonyl compounds catalyzed by conventional palladium complexes in the presence of chloroform
-
Arylboronic acids react with aldehydes and α,β-unsaturated carbonyl compounds in the presence of a base and a catalytic amount of a palladium(0) complex with chloroform, affording the corresponding addition products in good yields, and chiral benzhydrol was obtained with up to 43% e.e. using (S,S)-bppm as a ligand. General palladium complexes have no catalytic activity without chloroform. Because chloroform is essential for this reaction, these reactions would be promoted by dichloromethylpalladium(II) species.
- Yamamoto, Tetsuya,Iizuka, Michiko,Takenaka, Hiroto,Ohta, Tetsuo,Ito, Yoshihiko
-
experimental part
p. 1325 - 1332
(2009/09/28)
-
- Rhodium catalyzed 1,4-conjugate addition of 1,5-azastibocines with electron deficient olefins
-
The rhodium-catalyzed reaction of Sb-aryl-1,5-azastibocines with α,β-unsaturated ketones and esters is described. Exclusive formation of 1,4-conjugate adduct was achieved in aqueous NMP (N-methyl-2-pyrrolidinone) in the presence of 5 mol% of [RhCl(cod)]s
- Kakusawa, Naoki,Kurita, Jyoji
-
scheme or table
p. 1502 - 1504
(2009/10/24)
-
- Conjugate addition of organocopper reagents in dichloromethane to α,β-unsaturated esters
-
Organocopper reagents in conjunction with Lewis acid activators provide greater stability than traditional cuprate reagents while maintaining the reactivity needed for conjugate addition reactions in dichloromethane. Whereas cuprates engage in cross-coupl
- Yang, Jingyue,Dudley, Gregory B.
-
p. 7887 - 7889
(2008/03/11)
-
- Highly regioselective anti-markovnikov palladium-borate-catalyzed methoxycarbonylation reactions: Unprecedented results for aryl olefins
-
(Chemical Equation Presented) A general, highly efficient and regioselective methoxycarbonylation, by means of a palladium-salicylicborate- catalyzed protocol, of terminal alkyl and aryl olefins is described. The substrates include aliphatic alkenes, allylbenzenes, and styrene derivatives. The yields are very good (60-92%) and the regioselectivity, in favor of the linear ester, is up to quantitative - unprecedented in the case of styrenes.
- Vieira, Tiago O.,Green, Mike J.,Alper, Howard
-
p. 6143 - 6145
(2007/10/03)
-
- Rhodium-catalysed 1,4-addition of diarylindium hydroxides to α,β-unsaturated carbonyl compounds
-
Diarylindium(III) hydroxides react with α,β-unsaturated carbonyl compounds in the presence of a rhodium catalyst to afford the 1,4-addition products in high yield. This reaction demonstrates the utility of diarylindium(III) hydroxide as an aryl source with rhodium catalysts. The Royal Society of Chemistry 2005.
- Miura, Tomoya,Murakami, Masahiro
-
p. 5676 - 5677
(2007/10/03)
-
- Palladium-catalyzed enantioselective conjugate addition of arylboronic acids
-
(Chemical Equation Presented) The first asymmetric palladium-catalyzed conjugate addition of arylboronic acids to α,β-unsaturated aldehydes, ketones, and esters is described. For cyclic substrates, excellent chemo-, regio-, and enantioselectivities are achieved when a Pd(O2CCF 3)2/DuPHOS catalyst is applied.
- Gini, Francesca,Hessen, Bart,Minnaard, Adriaan J.
-
p. 5309 - 5312
(2007/10/03)
-
- QUINOLINE-2-ONE-DERIVATIVES FOR THE TREATMENT OF AIRWAYS DISEASES
-
Compounds of formula (I) in free or salt form, wherein -C-Y-, R1 and R2 are G have the meanings as indicated in the specification, are useful for treating conditions that are prevented or alleviated by activation of the (β2-adrenoreceptor. Pharmaceutical compositions that contain the compounds and a process for preparing the compounds are also described.
- -
-
Page/Page column 39
(2008/06/13)
-
- Electrochemically induced Favorsky rearrangement of alkyl benzyl ketones
-
Electrolysis of alkyl benzyl ketones in MeOH in an undivided electrolyzer in the presence of the Nal-NaOH mediator system induces the process similar to the Favorsky rearrangement to produce arylalkanecarboxylates in 80-90% yield (per substance) and with the 50-55% current efficiency.
- Elinson,Feducovich,Dorofeev,Vereshchagin,Nikishin
-
p. 228 - 231
(2007/10/03)
-
- Lipase-Catalyzed Kinetic Resolution on Solid-Phase via a "Capture and Release" Strategy
-
The lipase-catalyzed kinetic resolution of (R/S)-3-phenylbutyric acid 2 using solid-supported cyclohexane-1,3-dione (CHD) 6 is described. In each case the predominant enantiomer observed, after cleavage from the resin, was (R)-(?)-3-phenylbutyric acid (R)-2 (ee > 99%) rather than the expected (S)-enantiomer of 2. This observation is in contrast to the fact that Chromobacterium viscosum lipase shows high enantiospecificity for the (S)-enantiomer in the corresponding solution-phase hydrolysis reactions. The (R)-acyl group was subsequently released from the resin by NaOH hydrolysis, and the yield of the reaction could be improved by triple acylation of the resin. Copyright
- Humphrey, Cara E.,Turner, Nicholas J.,Easson, Morag A. M.,Flitsch, Sabine L.,Ulijn, Rein V.
-
p. 13952 - 13953
(2007/10/03)
-
- Silicone as an organosilicon reagent 2. Rhodium-catalyzed conjugate addition of the silicone reagent to α,β-unsaturated carbonyl compounds
-
The reaction of poly(phenylmethylsiloxane) with α,β-unsaturated carbonyl compounds in the presence of aqueous K2CO3 and 3 mol% of [Rh(OH)(cod)]2 gives 1,4-conjugate addition product in good yields. Arylchlorosilanes also u
- Koike, Tooru,Du, Xiaoli,Mori, Atsunori,Osakada, Kohtaro
-
p. 301 - 303
(2007/10/03)
-
- Pyran-2-ones and 5,6-dihydropyran-2-ones useful for treating hyperplasia and other diseases
-
Certain 2H-pyran-2-ones are useful for treating benign prostatic hypertrophy or hyperplasia, prostatic cancer, alopecia, hirsutism, acne vulgaris and seborrhea.
- -
-
-
- Quasi-nature catalysis: Conjugated addition of unsaturated carbonyl compounds with aryl and vinyltin reagents catalyzed by rhodium in air and water
-
In air and water, trialkylphenyl- or trialkylvinylstannanes react with α,β-unsaturated esters and ketones to give the corresponding conjugated addition products in high yields in the presence of a rhodium catalyst.
- Venkatraman, Sripathy,Meng, Yue,Li, Chao-Jun
-
p. 4459 - 4462
(2007/10/03)
-
- Lewis acid-promoted transesterification of N-acyl oxazolidinones under mild conditions
-
N-Acyl oxazolidinones are smoothly converted to the corresponding esters by Lewis acid-promoted transesterification. Mild reaction conditions suppress epimerization or racemization of chiral substrates and allow acid-sensitive groups to survive.
- Orita, Akihiro,Nagano, Yoshifumi,Hirano, Junichi,Otera, Junzo
-
p. 637 - 639
(2007/10/03)
-
- Rhodium catalyzed conjugated addition of unsaturated carbonyl compounds by triphenylbismuth in aqueous media and under an air atmosphere
-
In the presence of a rhodium catalyst, α,β-unsaturated esters and ketones react with triphenylbismuth in aqueous media and under an air atmosphere to give the corresponding conjugated addition products in high yields.
- Venkatraman, Sripathy,Li, Chao-Jun
-
p. 781 - 784
(2007/10/03)
-
- Asymmetric conjugate 1,4-addition of arylboronic acids to α,β-unsaturated esters catalyzed by rhodium(I)/(S)-binap
-
Arylboronic acids underwent the conjugate 1,4-addition to α,β-unsaturated esters to give β-aryl esters in high yields in the presence of a rhodium(I) catalyst. The addition of arylboronic acids to isopropyl crotonate resulted in high yields and high enantioselectivity exceeding 90% ee in the presence of 3 mol % of Rh(acac)(C2H4)2 and (S)-binap at 100 °C. The rhodium/(S)-binap complex provided (R)-3-phenylbutanoate in the addition of phenylboronic acid to benzyl crotonate. The effects on the enantioselectivity of chiral phosphine ligands, rhodium precursors, and substituents on α,β-unsaturated esters are discussed, as well as the mechanistic aspect of the catalytic cycle.
- Sakuma, Satoshi,Sakai, Masaaki,Itooka, Ryoh,Miyaura, Noria
-
p. 5951 - 5955
(2007/10/03)
-
- An efficient preparative scale resolution of 3-phenylbutyric acid by lipase from Burkholderia cepacia (Chirazyme L1)
-
Lipase from Burkholderia cepacia (Chirazyme L1) catalysed the highly enantioselective hydrolysis of racemic methyl 3-phenylbutyrate to afford (R)- (-)-methyl 3-phenylbutyrate of >98% ee (E>50). The resolution was performed at 150 g scale yielding 68.7 g of (R)-(-)-methyl 3-phenylbutyrate (>98% ee, 92% yield on enantiomer) and (S)-(+)-3-phenylbutyric acid of 89% ee.
- Varadharaj, Govindarajulu,Hazell, Keith,Reeve, Christopher D.
-
p. 1191 - 1195
(2007/10/03)
-
- Homolytic Reactions of Ligated Boranes. Part 16. Enantioselective Hydrogen-atom Abstraction by Chiral Amine-Boryl Radicals: Catalytic Kinetic Resolution of Esters and of Camphor
-
UV irradiation of an oxirane solution containing di-tert-butyl peroxide, an amine-alkylborane complex (in which the B-alkyl group is optically active) and a racemic ester or camphor as substrate, gives rise initially to the tert-butoxyl radical which rapidly abstracts hydrogen from the complex to form an optically active amine-boryl radical.The amine-boryl radical then abstracts hydrogen enantioselectively from a C-H group α to the carbonyl group in the substrate to regenerate the amine-alkylborane.This abstraction reaction has been used to bring about catalytic kinetic resolution of the substrate, using the bis(isopinocampheylborane) complex of N,N,N',N'-tetramethylethylenediamine and some of its derivatives as catalysts.After partial consumption of the substrate, the amount remaining and its enantiomeric excess (ee) have been used to derive enantioselectivity constants for hydrogen-atom abstraction.Enantioselectivity varies considerably with the structure of the substrate.The highest selectivity was observed for hydrogen abstraction from dimethyl 2,2-dimethyl-1,3-dioxolane-trans-4,5-dicarboxylate, when after 75percent consumption of initially-racemic ester at -90 deg C, the residual substrate showed an ee of 97percent.A transition-state model is proposed to account for the observed enantioselectivities.
- Mok, Pearl L. H.,Roberts, Brian P.,McKetty, Paula T.
-
p. 665 - 674
(2007/10/02)
-
- Electrochemical oxidation of ketones in methanol in the presence of alkali metal bromides
-
Electrochemical oxidation of methyl ketones in methanoi in the presence of alkali metal bromides affords methyl carboxylates. Benzyl alkyl ketones are transformed under similar conditions into methyl 3-phenylalkanoates, while ketones lacking σ-benzyl or σ-methyl group are oxidized into σ-hydroxyketals.
- Nikishin, Gennady I.,Elinson, Michail N.,Makhova, Irina V.
-
p. 895 - 905
(2007/10/02)
-
- 13C magnetic resonance studies. 142. The fate of highly substituted acyclic ketones in strong base: β-enolization, Haller-Bauer cleavage, and an alkyl to aryl acyl shift
-
Di-tert-butyl ketone (2a), 5,5,7,7-tetramethyl-6-undecanone (2b), and 2,4-dimethyl-2,4-diphenyl-3-pentanone (2d) have been found to undergo slow rearrangement by β-proton abstraction from the α-methyl groups upon treatment with t-BuO-/t-BuOH/>185 deg C.This is in contrast to the absence of such rearrangement in cyclic systems.It is the only significant process observed for 2a and 2b, whereas with 2d and its monomethyl analog 22 Haller-Bauer type cleavage and an unprecedented 1,3-acyl shift from sp3 to sp2 carbon accompany the β-enolate rearrangement.The rates of 1H/2H exchange of the methyl protons in 2a, b were found to be similar to those reported for a variety of cyclic systems but this exchange does not occur in 2d, where only aryl proton exchange was observed.
- Dyllick-Brenzinger, Rainer A.,Patel, Vijay,Rampersad, Mollin B.,Stothers, J. B.,Thomas, Shirley E.
-
p. 1106 - 1115
(2011/08/10)
-
- Electroorganic Chemistry. 124. Electroreductive Intramolecular Coupling of α-(ω-Bromoalkyl) β-Keto Esters
-
Intramolecular coupling occurs when cyclic α-(bromomethyl) β-keto esters are electrochemically reduced in the presence of trimethylsilyl chloride and one-carbon ring-enlarged products are obtained in reasonable yields.Electroreduction of α-(γ-bromopropyl) β-keto esters also affords the corresponding five-membered cyclized products and/or the corresponding ring-opened compounds.The ease of ring opening of the cyclized products is highly influenced by their stereoconfiguration.Electroreduction of α-(β-bromoethyl) β-keto ester gives the product formed by the reductive elimination of the bromoethyl group whereas α-(δ-bromobutyl) β-keto ester yields the product of the reductive elimination of bromine.This electroreductive intramolecular coupling is initiated by the reduction of the carbon-bromine bond and proceeds through a carbanion intermediate.
- Shono, Tatsuya,Kise, Naoki,Uematsu, Nobuyuki,Morimoto, Shinji,Okazaki, Eiichi
-
p. 5037 - 5041
(2007/10/02)
-
- Convenient Synthetic Sequence for the Preparation of Indanones
-
A convenient and general methods is reported for the synthesis of indanones from aryl ketones or aldehydes.
- Smonou, Ioulia,Orfanopoulos, Michael
-
p. 1387 - 1397
(2007/10/02)
-
- CHLOROSILANE-ACCELERATED CONJUGATE ADDITION OF CATALYTIC AND STOICHIOMETRIC ORGANOCOPPER REAGENTS
-
Trialkylsilyl chlorides, particularly in combination with hexamethylphosphoramide or 4-dimethylaminopyridine, dramatically accelerates the conjugate addition of catalytic and stoichiometric organocopper reagents onto enones, enals, and enoates, in which very high degrees of stereo- and chemoselectivities were observed.
- Matsuzawa, Satoshi,Horiguchi, Yoshiaki,Nakamura, Eiichi,Kuwajima, Isao
-
p. 349 - 362
(2007/10/02)
-
- Optimization of asymmetric hydrogenation of 3-phenyl-3-butenoic acid catalyzed by rhodium(I)-4,5-bis-2,2-dimethyldioxolane (DIOP)
-
Enantioselective, homogeneous hydrogenation of 3-phenyl-3-butenoic acid (1) has extensively been examined in the presence of the rhodium(I)/4,5-bis-2,2-dimethyldioxolane (DIOP) catalyst systems.Optimization of the reaction conditions was undertaken mainly by controlling effects of added tertiary amines as well as solvent polarities on the enantio-selectivity of the product.The best asymmetric yield (85.1percent e.e.) was attained when the hydrogenation was carried out in the presence of triethylamine (5 molpercent) in 75percent aqueous methanol using a neutral rhodium-DIOP catalyst.
- Yamamoto, Keiji,Ikeda, Kiyoshi,Yin, Leong Kwai
-
p. 319 - 332
(2007/10/02)
-
- ORGANOCOPPER-IODOSILANE COMBINATIONS IN CONJUGATE ADDITIONS
-
This paper concerns new possibilities opened by the addition of (mono)organocopper compounds and iodotrimethylsilane (TMSI) to α,β-unsaturated ketones and esters giving the silyl enol ethers and ketene acetals, respectively.We demonstrate the homogeneous addition of methylcopper-tributyl-phosphine-iodotrimethylsilane to methyl cinnamate, the use of organocopper-bromotrimethylsilane combinations, the dominating formation of Z-silyl enol ethers on conjugate addition of methyl- and butylcopper/TMSI to benzalacetone, and the formation of silyl enol ethers in other additions of organocopper compounds and TMSX to conjugated ketones.The Z-selectivity for addition to benzalacetone corresponds to s-cis conformations in ?-complexes between copper(I) chloride and 1-penten-3-one or 3-buten-2-one.The stereoselectivity could support a reaction path via ?-complexes between organocopper-iodotrimethylsilane complexes and s-cis conformers of the substrates.
- Bergdahl, Mikael,Lindstedt, Eva-Lotte,Nilsson, Martin,Olsson, Thomas
-
p. 535 - 544
(2007/10/02)
-
- Stereoselective Alkylation of Arenes with Threonine Trifluoromethanesulfonates
-
N-Phthaloylthreonine and -allothreonine methyl esters 3 react with trifluoromethanesulfonic anhydride / pyridine in dichloromethane to give threonine and allothreonine, respectively, trifluoromethanesulfonates 4 in quantitative yields.Arenes can be alkyla
- Effenberger, Franz,Weber, Thomas
-
p. 421 - 430
(2007/10/02)
-
- CHLORO- AND IODOTRIMETHYLSILANE-ACTIVATED ADDITIONS OF ORGANOCOPPER COMPOUNDS TO ENONES AND ENOATES
-
Organocopper compounds add to enones and enoates in the presence of chloromethylsilane in ether giving the conjugate adducts in preparatively usefu yields via the silyl enol ethers.Presence of lithium iodide is important and excess of chlorotrimethylsilane accelerates the reactions.The combination of organocopper compound, iodotrimethylsilane and dimethyl sulfide gave faster reactions and very high yields, particularly in dichloromethane, where the reaction mixtures gradually became homogeneous.
- Bergdahl, Mikael,Lindstedt, Eva-Lotte,Nilsson, Martin,Olsson, Thomas
-
p. 2055 - 2062
(2007/10/02)
-