1191-99-7Relevant articles and documents
Small bite-angle P-OP ligands for asymmetric hydroformylation and hydrogenation
Fernandez-Perez, Hector,Benet-Buchholz,Vidal-Ferran, Anton
, p. 3634 - 3637 (2013)
A series of small bite-angle phosphine-phosphite (P-OP) ligands have been synthesized by a two-step method. The key intermediate was prepared by an unprecedented asymmetric carbonyl reduction of a phosphamide using the CBS (Corey-Bakshi-Shibata) catalyst. The topology of these ligands (a configurationally stable stereogenic carbon with two heteroatom substituents) and their small bite-angle (created by the close proximity of the two ligating groups to the metal center) together provide a rigid asymmetric environment around this center, enabling high stereoselectivity in hydroformylations and hydrogenations of standard substrates.
Aerial oxidation of tetrahydrofuran to 2-hydroxotetrahydrofuran in the presence of a trimeric CuI complex [Cu3L3] (HL = tBuNHC(S)NHP(S)(OiPr)2) and trapping of the unstable product at recrystallization
Luckay, Robert C.,Sheng, Xia,Strasser, Christoph E.,Raubenheimer, Helgard G.,Safin, Damir A.,Babashkina, Maria G.,Klein, Axel
, p. 2835 - 2840 (2010)
The reaction of the potassium salt of N-thiophosphorylated thiourea tBuNHC(S)NHP(S)(OiPr)2 (HL) with Cu(NO3)2 in aqueous EtOH leads to the trinuclear [Cu3(tBuNHC(S)NP(S)(OiPr) 2-S,S′)3] ([Cu3L3]) complex. It was established that [Cu3L3] provokes the aerobic oxidation of tetrahydrofuran to 2-hydroxotetrahydrofuran and traps the latter at crystallization. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Tautomerism and vapor-phase transformations of 2-hydroxytetrahydrofuran
Lebedev,Leite,Fleisher,Stonkus
, p. 775 - 778 (2000)
The relative stability of 2-hydroxytetrahydrofuran and the tautomeric 4-hydroxybutanal was determined by the semi-empirical AM1 method. It was concluded that the cyclic tautomer predominates in the gas phase at 25°C. Vapor-phase dehydration of 2-hydroxytetrahydrofuran in the presence of porcelain and silica gel L leads to a quantitative yield of 2,3-dihydrofuran.
DOUBLE BOND MIGRATION OF ALLYL ETHERS OVER SOLID BASE CATALYSTS
Matsuhashi, Hiromi,Hattori, Hideshi,Tanabe, Kozo
, p. 341 - 342 (1981)
Double bond migrations of allyl ethers were carried out over various solid base catalysts.Magnesium oxide, CaO, SrO, and La2O3 exhibited high activities.High cis/trans ratios in the products suggest that the reaction proceed via cis-?-allylic anions as intermediates
Highly efficient rhodium catalysts for the asymmetric hydroformylation of vinyl and allyl ethers using C1-symmetrical diphosphite ligands
Gual, Aitor,Godard, Cyril,Castillon, Sergio,Claver, Carmen
, p. 463 - 477 (2010)
Here, we describe the successful application of novel glucofuranose-derived 1,3-diphosphites in the rhodium-catalysed asymmetric hydroformylation of vinyl acetate, 2,5-dihydrofuran and 2,3-dihydrofuran. In the hydroformylation of vinyl acetate, total regioselectivity and high ee (up to 73%) were obtained. When 2,3- and 2,5-dihydrofuran were the substrates, total chemo- and regioselectivities were achieved together with ees up to 88%. These results correspond to the highest ee values reported to date in the asymmetric hydroformylation of these substrates. The HP-NMR studies of the [RhH(CO) 2(L)] species (L=15 and 17) demonstrated that both ligands coordinate to the Rh centre in an eq-eq fashion. The complex [RhH(CO)2(15)] was detected as a single isomer with characteristic features of eq-eq coordination. However, the broadening of the corresponding signals indicated that this species is rapidly interchanging in solution. In contrast, complex [RhH(CO) 2(17)] was detected as a mixture of two conformational isomers at low temperature due to the greater flexibility of the monocyclic backbone of this ligand.
Fine-tunable monodentate phosphoroamidite and aminophosphine ligands for Rh-catalyzed asymmetric hydroformylation
Mazuela, Javier,Pmies, Oscar,Dieguez, Montserrat,Palais, Laetitia,Rosset, Stephane,Alexakis, Alexandre
, p. 2153 - 2157 (2010)
A biaryl-based monophosphoroamidite L1-L4a-f and aminophosphine L5-L7a-f ligand library was screened in the Rh-catalyzed asymmetric hydroformylation of several vinylarenes and heterocyclic olefins. Our results indicate that the selectivity is strongly dependent on the ligand parameters and on the substrate type. Enantioselectivities (up to 46%) were moderate in the hydroformylation of several vinylarenes S1-S5 and promising (up to 58%) for the more challenging heterocyclic olefins S6-S9.
Hoveyda-Type Quinone-Containing Complexes – Catalysts to Prevent Migration of the Double Bond under Metathesis Conditions
Kajetanowicz, Anna,Milewski, Mariusz,Rogińska, Joanna,Gajda, Roman,Wo?niak, Krzysztof
, p. 626 - 638 (2017)
Three new quinone-containing Hoveyda-type complexes have been synthesised and fully characterised. Their ability to suppress undesired double-bond migration along the carbon chain during metathesis reactions was examined. It was proved that these catalysts decrease the amounts of undesired side-products with a shifted double bond in the reaction mixture.
Chiral Diaryliodonium Phosphate Enables Light Driven Diastereoselective α-C(sp3)-H Acetalization
Ye, Baihua,Zhao, Jie,Zhao, Ke,McKenna, Jeffrey M.,Toste, F. Dean
, p. 8350 - 8356 (2018)
C(sp3)-H bond functionalization has emerged as a robust tool enabling rapid construction of molecular complexity from simple building blocks, and the development of asymmetric versions of this reaction creates a powerful methodology to access enantiopure sp3-rich materials. Herein, we report the stereoselective functionalization of C(sp3)-H bonds of cyclic ethers employing a photochemically active diaryliodonium salt in combination with an anionic phase-transfer catalyst. The synthetic strategy outlined herein allows for regio- and stereochemical control in the α-C-H acetalization of furans and pyrans using alcohol nucleophiles, thus providing the ability to control the configuration at the stereogenic exocyclic acetal carbon.
Rh-catalyzed asymmetric hydroformylation of heterocyclic olefins using chiral diphosphite ligands. Scope and limitations
Mazuela, Javier,Coll, Mercedes,Pamies, Oscar,Dieguez, Montserrat
, p. 5440 - 5445 (2009)
(Chemical Equation Presented) We used a series of diphosphite ligands to study the effect of the ligand backbone, the length of the bridge, and the substituents of the biphenyl moieties and determine the scope of this type of ligand in the Rh-catalyzed asymmetric hydroformylation of several hetereocylic olefins. By carefully selecting the ligand components, we achieved high chemo-, regio-, and enantioselectivities in different substrate types. Unprecedentedly high enantioselectivities for five-membered heterocyclic olefins were therefore obtained. Note that both enantiomers of the hydroformylation products can be synthesized using the same ligand by a simple substrate change. For the seven-membered heterocyclic dioxepines, our results are among the best obtained. Also, both enantiomers of the hydroformylation products can be obtained by using pseudoenantiomer ligands or by carefully tuning the ligand parameters.
Synthesis and Properties of Furan Derivatives 2. Role of the Halogen in RMgX in Reactions with Alkoxytetrahydrofurans
Polivin, Yu. N.,Trofimova, M. V.,Karakhanov, R. A.,Ageev, E. A.
, p. 494 - 496 (1992)
Heating 2-methoxytetrahydrofuran with ethylmagnesium bromide in benzene at reflux leads to the formation of 2-ethoxytetrahydrofuran and slight amounts of 4-methoxy-1-hexanol.Under analogous conditions, 2-ethoxytetrahydrofuran is quantitatively cleaved by
