- Fast and unprecedented chemoselective hydroformylation of acrylates with a fluoropolymer ligand in supercritical CO2
-
A fluorous polymeric phosphine, when combined with supercritical CO2 (scCO2) and rhodium, effects fast and highly chemoselective hydroformylation of acrylates, one of the least reactive olefins in hydroformylation reactions.
- Hu, Yulai,Chen, Weiping,Banet Osuna, Anna M.,Iggo, Jon A.,Xiao, Jianliang
-
-
Read Online
- Catalyst composition containing bidentate phosphine ligand and application thereof
-
The catalyst composition comprises a bidentate phosphine ligand and a rhodium complex, wherein the skeleton of the bidentate phosphine ligand not only has C. 2 The symmetry and the appropriate rigidity, and the phosphine ligand derived based on the skeleton can provide effective steric hindrance around the catalyst center metal, so that the selectivity of the catalyst can be remarkably improved, the aldehyde yield is not lower 92% when the catalyst combination is applied to the hydroformylation reaction, and the selectivity of n-aldehyde is not lower 90%. In addition, the raw materials olefins with different structures can obtain outstanding reaction rate and normal aldehyde selectivity as compared with the existing catalyst systems, and can be suitable for the hydroformylation reaction of more types of olefins.
- -
-
Paragraph 0068; 0089-0092
(2021/11/03)
-
- Catalytic isomerization-hydroformylation of olefins by rhodium salicylaldimine pre-catalysts
-
A series of new Schiff-base rhodium(i) water-soluble complexes (C1-C3), were prepared and characterized. These complexes served as catalyst precursors for the hydroformylation of 1-octene and resulted in excellent substrate conversions (>98%) with 100% chemoselectivities to aldehydes, under mild conditions. Notably, good regioselectivities towards branched aldehydes were observed clearly demonstrating the catalysts’ ability in thermodynamically favoured isomerization followed by hydroformylation (n/iso ratio ranging between 0.7-1.2). Interestingly, catalystC1uniquely promoted contra-thermodynamic isomerization of 2-octene to 1-octene with up to 50% conversion. The efficacy of catalystC1was further evaluated in the hydroformylation of longer chain olefins (C10-C12), methyl acrylate, ethyl acrylate and styrene. The catalyst displayed conversions >99% with the long chain substrates and much lower conversions with the acrylates. These water-soluble (pre)catalysts were recycled up to three times with no significant loss in catalytic activity and selectivity. Mercury poisoning tests were conducted and the experiments revealed that the conversion of the substrates into aldehydes was due to molecular active catalysts and not as a result of colloidal particles that could have formedin situthrough the decomposition of the catalyst precursor. Finally, the molecular catalyst responsible for activity was established using preliminary computational calculations.
- Sekoto, Pamela N.,Magengenene, Tseliso M.,Matsinha, Leah C.,Tia, Richard,Darkwa, James,Makhubela, Banothile C. E.
-
p. 8751 - 8762
(2020/06/08)
-
- Insertion of Alkylidene Carbenes into B-H Bonds
-
We have developed a protocol for insertion of alkylidene carbenes into the B-H bonds of amine-borane adducts, enabling, for the first time, the construction of C(sp2)-B bonds by means of carbene-insertion reactions. Various acyclic and cyclic alkenyl borane-amine adducts were prepared from readily accessible starting materials in good to high yields and were subsequently subjected to a diverse array of functional group transformations. The unprecedented spiro B-N heterocycles prepared in this study have potential utility as building blocks for the synthesis of pharmaceuticals. Preliminary mechanistic studies suggest that insertion of the alkylidene carbenes into the B-H bonds of the amine-borane adducts proceeds via a concerted process involving a three-membered-ring transition state.
- Yang, Ji-Min,Guo, Feng-Kai,Zhao, Yu-Tao,Zhang, Qiao,Huang, Ming-Yao,Li, Mao-Lin,Zhu, Shou-Fei,Zhou, Qi-Lin
-
supporting information
p. 20924 - 20929
(2020/12/23)
-
- Hydroformylation of unsaturated esters and 2,3-dihydrofuran under solventless conditions at room temperature catalysed by rhodium: N-pyrrolyl phosphine catalysts
-
Rhodium complexes of the type HRh(CO)L3 (where L is an N-pyrrolyl phosphine, such as P(NC4H4)3, PPh(NC4H4)2, or PPh2(NC4H4)) were applied in the hydroformylation of less reactive unsaturated substrates, namely allyl acetate, butyl acrylate, methyl acrylate, 2,3-dihydrofuran and vinyl acetate. Even at room temperature, these catalysts enabled complete substrate conversion and high chemoselectivity towards the corresponding aldehydes. High conversion of vinyl acetate (88% in 6 h) to the branched aldehyde was obtained with HRh(CO)[P(NC4H4)3]3 at 25 °C. An increase of the turnover frequency, TOF, up to 2000 mol mol-1 h-1 was achieved in this reaction under 20 bar of syngas (H2/CO = 1) at 80 °C. The introduction of chiral phosphines, BINAP or Ph-BPE, to this system resulted in the production of a branched aldehyde with enantioselectivity, ee, up to 44 and 81%, respectively. High activity combined with high enantioselectivity was achieved due to the formation of the mixed rhodium hydrides HRh(CO)[P(NC4H4)3](BINAP) and HRh(CO)[P(NC4H4)3](Ph-BPE), identified by the NMR method.
- Alsalahi,Trzeciak
-
p. 16990 - 16999
(2019/11/14)
-
- Tandem and One-Pot Hydroformylation/Michael Reactions of Acrylates
-
The combination of various reactions in one operational step leads to many advantages in synthetic strategies, such as a lower consumption of resources, effort, and time, when intermittent workup and purification steps can be avoided. The hydroformylation reaction of acrylates gives access to 2-formylpropanoates, which thanks to their structural features constitute useful intermediates in the synthesis of more complex compounds. Herein, we report a simple and convenient one-pot strategy to synthesize functionalized carbonyl compounds starting from these readily available substrates, via tandem or one-pot hydroformylation, Michael addition, and aldol reactions.
- Quintero-Duque, Samuel,Fleischer, Ivana
-
p. 925 - 932
(2017/02/15)
-
- Selective hydroformylation of alkyl acrylates using [2,2′-bis(dipyrrolylphosphinooxy)-1,1′-(±)-binaphthyl]/Rh catalyst: reversal of regioselectivity
-
The rhodium-catalyzed hydroformylation of alkyl acrylates with different P-N diphosphine ligands is investigated here. Under mild conditions (syngas pressure: 2 MPa, 20 °C), 2,2′-bis(dipyrrolylphosphinooxy)-1,1′-(±)-binaphthyl (L1) rhodium catalyst could give good conversion of ethyl acrylate (82.9%) in 12 h and exclusive branched aldehyde selectivity of >99.0%. More importantly, on elevating the temperature to 90 °C, this Rh system could preferentially afford the linear aldehyde with 96.1% regioselectivity, and the TOF could reach up to 9000 h?1. Deuterioformylation was conducted to explore the mechanism of regioselectivity reversal, and the results established that the reversible rhodium hydride addition to form the Rh-alkyl species might play a vital role in this reversal. The β-hydride elimination of branched Rh-alkyl species was comparatively stronger than that of linear ones under increased temperature, probably because L1 could cause comparatively larger steric repulsion in branched Rh-alkyl species under high temperature, due to its bulky and rigid binaphthyl backbone characteristics. In turn, the linear Rh-alkyl species progress to linear aldehyde was facilitated.
- Shu, Xiao,Liang, Haoran,Wu, Qianhui,Zhou, Fanding,Zheng, Xueli,Fu, Haiyan,Xu, Bin,Li, Ruixiang,Zhang, Chunchun,Chen, Hua
-
p. 14816 - 14823
(2017/03/16)
-
- HETEROCYCLIC MODULATORS OF LIPID SYNTHESIS FOR USE AGAINST CANCER AND VIRAL INFECTIONS
-
Heterocyclic modulators of lipid synthesis are provided as well as pharmaceutically acceptable salts thereof; pharmaceutical compositions comprising such compounds; and methods of treating conditions characterized by disregulation of a fatly acid synthase pathway by the administration of such compounds. (I)
- -
-
Page/Page column 39
(2016/03/29)
-
- AMIDO-FLUOROPHOSPHITE COMPOUNDS AND CATALYSTS
-
Amido-fluorophosphite compounds and catalyst systems comprising at least one amido-fluorophosphite ligand compound in combination with a transition metal are described. Moreover, the use of amido-fluorophosphite containing catalysts for transition metal catalyzed processes, especially to the hydroformylation of various olefins to produce aldehydes are also described.
- -
-
Page/Page column 27
(2013/03/26)
-
- General, Robust, and stereocomplementary preparation of α,β-disubstituted α,β-unsaturated esters
-
An (E)- and (Z)-stereocomplementary preparative method for α,β-disubstituted α,β-unsaturated esters Is performed via three general and robust reaction sequences: (i) TI-Claisen condensation (formylation) of esters to give α-formyl esters (12 examples, 60-99%), (II) (E)- and (Z)-stereocomplementary enol ρ-toluenesulfonylation (tosylation) using TsCI-N-methylimidazole (NMI)-Et3N and LiOH (24 examples, 82-99%), and (iii) stereoretentive Suzuki-Miyaura cross-coupling (18 examples, 64-96%).
- Nakatsuji, Hidefumi,Nishikado, Hiroshi,Ueno, Kanako,Tanabe, Yoo
-
experimental part
p. 4258 - 4261
(2009/12/28)
-
- IMIDATE COMPOUND AND USE THEREOF FOR PEST CONTROL
-
There is provided a compound having an excellent controlling effect on arthropod pests represented by the formula (I-1): wherein Z represents an optionally substituted carbocyclic group or an optionally substituted heterocyclic group; G represents a -A1-R1
- -
-
Page/Page column 238-239
(2009/03/07)
-
- Process for preparing beta-L-2'deoxy-thymidine
-
The present invention relates to a new, essentially four-step process for preparing beta-L-2′-deoxy-thymidine starting from L-arabinose. The process according to the invention is particularly important for mass production of beta-L-2′-deoxy-thymidine.
- -
-
-
- Rapid hydroformylation of alkyl acrylates in supercritical CO2
-
Fast and regioselective hydroformylation of alkyl acrylates can readily be accomplished in supercritical CO2 (scCO2), which promotes the reaction probably via specific solvent-solute interactions.
- Hu,Chen,Banet Osuna,Stuart,Hope,Xiao
-
p. 725 - 726
(2007/10/03)
-
- HSAB driven chemoselectivity in alkylation of uracil derivatives. A high yielding preparation of 3-alkylated and unsymmetrically 1,3-dialkylated uracils
-
A qualitative hardness scale (N134) has been found for the conjugated bases of 2-methoxy-4(3H)-pyrimidinones 1-3 and applied to high yielding chemoselective N3 methylation, ethylation and benzylation reactions. Removal of the 2-methoxy group followed by a second alkylation affords unsymmetrically 1,3-disubstituted uracils.
- Gambacorta, Augusto,Farah, Mohamed Elmi,Tofani, Daniela
-
p. 12615 - 12628
(2007/10/03)
-
- Preparation and synthetic applications of sterically hindered secondary amines
-
The preparation of sterically hindered secondary amino esters from the reaction of N-protected α-amino aldehydes and 3-, or 2-oxo esters with α- amino esters by reductive amination is described. The resulting amino esters were converted to the β-lactam or acylated to form N-acyl secondary amides.
- Kim, Hwa-Ok,Carroll, Brian,Lee, Min S.
-
p. 2505 - 2515
(2007/10/03)
-
- Quaternary ammonium salts of phosphines as ligands and their recycling by membrane techniques or phase separation. Part I: Monophasic systems
-
Quaternary ammonium salts of functionalized tertiary amines may serve as ligands for transition metal catalysts in hydroformylation reactions. Besides these properties they offer special advantages for the catalyst separation using phase separation or membrane techniques.
- Bahrmann, Helmut,Haubs, Michael,Mueller, Thomas,Schoepper, Norbert,Cornils, Boy
-
p. 139 - 149
(2007/10/03)
-
- Influence of 1,4-Bis(diphenylphosphino)butane on the Hydroformylation of α,β-Unsaturated Esters Catalyzed by Zwitterionic, Cationic, and Neutral Rhodium(I) Complexes. The Asymmetric Hydroformylation od α-Methylene-γ-Butyrolactone
-
An investigation was made of the effect of 1,4-bis(diphenylphosphino)butane (dppb) on the regioselectivity of the hydroformylation of α,β-unsaturated esters with synthesis gas, catalyzed by rhodium(I) complexes.Excellent regioselectivity was obtained when dppb was added as a ligand for the reaction of methyl acrylate and α-methylene-γ-butyrolactone with synthesis gas.However, it inhibits the reaction when methyl methacrylate is used as the substrate.The asymmetric hydroformylation of α-methylene-γ-butyrolactone using (+)Cl(-) as the catalyst and (R)-BINAP as the chiral ligand (6:1 ratio of (R)-BINAP/Rh) gave an aldehydic lactone, containing a quaternary chiral center, in up to 37percent ee.
- Lee, Chul Woo,Alper, Howard
-
p. 499 - 503
(2007/10/02)
-
- Erhoehung der Katalyseaktivitaet bei der Hydroformylierung von Acrylsaeuremethylester durch Verwendung von Zweiphasen- und "Supported-Aqueous-Phase"-Systemen
-
Stichworte: Acrylsaeuremethylester.Hydroformylierung.Katalyse.Rhodiumkatalysatoren.Zweiphasenkatalyse
- Fremy, Georges,Monflier, Eric,Carpentier, Jean-Francois,Castanet, Yves,Mortreux, Andre
-
p. 1608 - 1610
(2007/10/02)
-
- A new, highly selective, water-soluble rhodium catalyst for methyl acrylate hydroformylation
-
Hydroformylation of methylacrylate to α-aldehyde can be achieved in a two-phase system in the presence of two new water-soluble phosphines.High yields and selectivities of α-aldehyde (ca. 80percent with a α/β ratio of 1:20) were obtained.Spectroscopic studies have been carried out and some new rhodium complexes formed in situ in catalytic systems have been identified.Keywords: Hydroformylation; Methyl acrylate; Water-soluble phosphines; Rhodium; Catalysis; Two phase system
- Fremy, Georges,Castanet, Yves,Grzybek, Ryszard,Minflier, Eric,Mortreux, Andre,et al.
-
-
- Process for the production of O 2,2'-anhydro-1-(β-D-arabinofuranosyl)thymine
-
In the disclosed process, an O2, 2' anhydro-1-(β-D-arabinofuranosyl)thymine is formed by condensing a 2-amino-β-arabinofurano[1',2':4,5,]-2-oxazoline with a compound of the formula STR1 wherein R1 is C1 -C4 alkyl; X is halogen or OR2, wherein R2 is H, C1 -C4 alkyl or phenyl; in the presence of a suitable solvent at about 0° C. to about 150° C. Catalytic agents such as dimethylaminopyridine and triethylamine may also be added to accelerate the reaction. Protected intermediates of the anhydronucleosides and aminooxazolines are also disclosed.
- -
-
-
- Evidence for Ketene Intermediates in the Reactions of 2-Oxobutanedioic Acid Diesters with Alcohols and Water
-
The reactions of diethyl ester (1a) and dimethyl ester (1b) of 3-methyl-2-oxobutanedioic acid with excess ethanol, methanol, or water in a sealed tube at approximately 125 deg C were studied.With methanol, 1a yielded mainly 3-methyl-2-oxobutanedioic acid 1-ethyl 4-methyl diester, 2a; with ethanol, 1b yielded mainly the 4-ethyl 1-methyl diester, 2b, while reaction of 1a with water yielded carbon dioxide, 2-oxobutanoic acid ethyl ester, 6, and 2-methyl-3-oxopropanoic acid ethyl ester, 7.These results suggested that the ketene intermediates 3-methyl-2,4-dioxo-3-butenoic acid ethyl or methyl ester, 4a and 4b, respectively, are implicated.The similarity of these reactions to those exhibited by ethyl acetoacetate, such as alkoxy group exchange, and formation of dehydroacetic acid, now thought to proceed by way of acetyl ketene, was demonstrated.
- Emerson, David W.,Titus, Richard L.,Gonzalez, Rowena M.
-
p. 3572 - 3576
(2007/10/02)
-
- New Access to dl-Paniculide A Using α-Phenylthio-β-Vinylbutenolide as Synthetic Block
-
A new synthetic approach to dl-paniculide A (1) based on the annulation of 2-formylpropionate with α-phenylthio-β-vinylbutenolide 4 is described.The annulation products 6a-6c was dehydrated to give 7, and the sulfoxide of 7 was submitted to sulfoxide-sulfinate rearrangement in aqueous media to yield 8a and 8b.The latter was converted to the former by configurational inversion of its hydroxyl group.Saturated lactone 11a obtained from 8a was homoprenylated, and after desilylation, the product 12b was selenenylated to give 13a.Alkaline hydrolysis followed by oxidative elimination of the selenenyl group provided 14a, which was then acetylated and oxidized with lead tetraacetate to yield 15a and 16a-16c. dl-Panaculide A was derived from 15a and 16a via 18a.
- Kido, Fusao,Noda, Yoshihiro,Yoshikoshi, Akira
-
p. 5467 - 5474
(2007/10/02)
-
- SYNTHESIS OF METHYL 3-(N'-ALKYLUREIDO)-2-METHYL-2-PROPENOATES AND THEIR CYCLIZATION TO 3-ALKYL-5-METHYLURACILS
-
Stereoisomeric methyl 3-(N'-alkylureido)-2-methyl-2-propenoates (Ia-Id) were prepared by acid-catalyzed reaction of N-alkylureas (R = methyl, benzyl, isopropyl and tert-butyl) with methyl 3-methoxy-2-methyl-2-propenoate (III).Reaction of the ester III with N-tert-butylthiourea afforded the thioureides (E)-Ie and (Z)-Ie.On treatment with sodium methoxide in methanol, compounds Ia-Ic cyclized to the corresponding 3-alkyl-5-methyluracils IIa-IIc whereas compounds Id and Ie underwent only a base catalyzed E/Z isomerization with (E)-isomers predominating.
- Ledvina, Miroslav,Farkas, Jiri
-
p. 676 - 688
(2007/10/02)
-
- Homogeneous Hydroformylation of Methyl Acrylate Catalyzed by Co2(CO)8-Di(tertiary phosphine) Complexes
-
Some complexes prepared in situ from Co2(CO)8 and various di(tertiary phosphine) as ligands have been found to be more active than Co2(CO)8 for the hydroformylation of methyl acrylate.The activity decreased in the order; Ph2P(CH2)2PPh2>Ph2PCCPPh2>cis-Ph2PCH=CHPPh2>Ph2P(CH2)3PPh2>none>Ph2PCH2PPh2>Ph2P(CH2)4PPh2.The most active catalyst (I) was obtained when a molar ratio of Ph2P(CH2)2PPh2 to Co2(CO)8 was ca. 0.5.The catalyst (I) is also active even at low pressure, where the decomposition of Co2(CO)8 occurs.
- Murata, Kazuhisa,Matsuda, Akio
-
p. 214 - 218
(2007/10/02)
-