932-66-1Relevant articles and documents
“Release and Catch” Effect of Perfluoroalkylsulfonylimide-Functionalized Imidazole/Pyridine on Br?nsted Acids in Organic Systems
You, Li,Ren, Xiao-Fei,Wang, Yun,Ma, Zhong-Hua,Gu, Yanlong,Ma, Jing-Zhong
, p. 3394 - 3401 (2016)
A “release and catch” method was developed by utilising the scavenging effect of a fluorous zwitterion on a homogeneous triflic acid (TfOH) catalyst in Michael addition and Rupe rearrangement. Both TfOH and the zwitterion were recycled with >90 % recovery using toluene. The zwitterions were designed by functionalising imidazole/pyridine with the perfluoroalkylsulfonylimide group. The “caught” TfOH was delivered to ethyl acetate and re-used. The smooth delivery was primarily because of the fluorous tail of the zwitterion, the hydrophobicity of which probably weakened the ability of the zwitterion to form H bonds, so that retro-ion-exchange occurred towards the formation of the acid and zwitterion. The method was universal for other strong Br?nsted acids such as H2SO4 and p-MeC6H4SO3H. The method combined the significant advantages of homogeneous catalysis and heterogeneous isolation. Based on the H0 acidity function and the 31P NMR chemical shift of Et3P=O adducts, it is reasonable to deduce that the decrease of the acid strength of the formed composites of Br?nsted acids and the zwitterion drove the scavenging effect.
Deep eutectic solvent-catalyzed Meyer-Schuster rearrangement of propargylic alcohols under mild and bench reaction conditions
Ríos-Lombardía, Nicolás,Cicco, Luciana,Yamamoto, Kota,Hernández-Fernández, José A.,Morís, Francisco,Capriati, Vito,García-álvarez, Joaquín,González-Sabín, Javier
supporting information, p. 15165 - 15168 (2020/12/21)
The Meyer-Schuster rearrangement of propargylic alcohols into α,β-unsaturated carbonyl compounds has been revisited by setting up an atom-economic process catalyzed by a deep eutectic solvent FeCl3·6H2O/glycerol. Isomerizations take place smoothly, at room temperature, under air and with short reaction times. The unique solubilizing properties of the eutectic mixture enabled the use of a substrate concentration up to 1.0 M with the medium being recycled up to ten runs without any loss of catalytic activity. This journal is
Hydration of terminal alkynes catalyzed by cobalt corrole complex
Lai, Jia-Wei,Liu, Zhao-Yang,Chen, Xiao-Yan,Zhang, Hao,Liu, Hai-Yang
supporting information, (2020/10/02)
Cobalt(III) corrole was firstly applied to the hydration of terminal alkynes. The alkyne hydration proceeded in good to excellent yield with 0.03 to 0.3 mol% cobalt corrole catalyst loading. A wide range of substrates were tolerated. Particularly, the reaction can give 90% yield in a gram scale experiment.
Access to Cycloalkeno[ c]-Fused Pyridines via Pd-Catalyzed C(sp2)-H Activation and Cyclization of N-Acetyl Hydrazones of Acylcycloalkenes with Vinyl Azides
Nie, Biao,Wu, Wanqing,Ren, Qingyun,Wang, Zhongqing,Zhang, Ji,Zhang, Yingjun,Jiang, Huanfeng
supporting information, p. 7786 - 7790 (2020/11/02)
A novel Pd(II)-catalyzed vinylic C-H activation and cyclization has been developed, reacting a series of small, medium, and large N-acetyl hydrazones of acylcycloalkenes with vinyl azides to access diverse cycloalkeno[c]-fused pyridine scaffolds. This protocol provides progress in C(sp2)-H bond activation of medium to large cycloalkenes, and the target products can be obtained in a specific regioselectivity with good functional group tolerance and a broad substrate scope.
Phosphorous acid promoted isomerization of propargyl alcohols to α,β-unsaturated carbonyl compounds
Gan, Xiaotang,Fu, Zuqi,Liu,Yan, Yani,Chen, Chao,Zhou, Yongbo,Dong, Jianyu
, (2019/07/12)
A metal-free and two-phase protocol for the Meyer-Schuster isomerization of propargyl alcohols to the corresponding α,β-unsaturated carbonyl compounds has been achieved in the presence of stoichiometric phosphorous acid aqueous solution, which produces the desired products in high yields with excellent stereoselectivity. Compared with the traditional methods, the procedure features broad scope of the substrates, mild conditions, and easy separation, providing an appealing alternative to the Meyer-Schuster reaction.
Balancing Bulkiness in Gold(I) Phosphino-triazole Catalysis
Zhao, Yiming,Wakeling, Matthew G.,Meloni, Fernanda,Sum, Tze Jing,van Nguyen, Huy,Buckley, Benjamin R.,Davies, Paul W.,Fossey, John S.
, p. 5540 - 5548 (2019/08/07)
The syntheses of a series of 1-phenyl-5-phosphino 1,2,3-triazoles are disclosed, within which, the phosphorus atom (at the 5-position of a triazole) is appended by one, two or three triazole motifs, and the valency of the phosphorus(III) atom is completed by two, one or zero ancillary (phenyl or cyclohexyl) groups respectively. This series of phosphines was compared with tricyclohexylphosphine and triphenylphosphine to study the effect of increasing the number of triazoles appended to the central phosphorus atom from zero to three triazoles. Gold(I) chloride complexes of the synthesised ligands were prepared and analysed by techniques including single-crystal X-ray diffraction structure determination. Gold(I) complexes were also prepared from 1-(2,6-dimethoxy)-phenyl-5-dicyclohexyl-phosphino 1,2,3-triazole and 1-(2,6-dimethoxy)-phenyl-5-diphenyl-phosphino 1,2,3-triazole ligands. The crystal structures thus obtained were examined using the SambVca (2.0) web tool and percentage buried volumes determined. The effectiveness of these gold(I) chloride complexes to serve as precatalysts for alkyne hydration were assessed. Furthermore, the regioselectivity of hydration of but-1-yne-1,4-diyldibenzene was probed.
Cationic Co(I)-intermediates for hydrofunctionalization reactions: Regio- A nd enantioselective cobalt-catalyzed 1,2-hydroboration of 1,3-dienes
Duvvuri, Krishnaja,Dewese, Kendra R.,Parsutkar, Mahesh M.,Jing, Stanley M.,Mehta, Milauni M.,Gallucci, Judith C.,Rajanbabu
supporting information, p. 7365 - 7375 (2019/05/16)
Much of the recent work on catalytic hydroboration of alkenes has focused on simple alkenes and styrene derivatives with few examples of reactions of 1,3-dienes, which have been reported to undergo mostly 1,4-additions to give allylic boronates. We find that reduced cobalt catalysts generated from 1,n-bis-diphenylphosphinoalkane complexes [Ph2P-(CH2)n-PPh2]CoX2; n = 1-5) or from (2-oxazolinyl)phenyldiarylphosphine complexes [(G-PHOX)CoX2] (G = 4-substituent on oxazoline ring) effect selective 1,2-, 1,4-, or 4,3-additions of pinacolborane (HBPin) to a variety of 1,3-dienes depending on the ligands chosen. Conditions have been found to optimize the 1,2-additions. The reactive catalysts can be generated from the cobalt(II)-complexes using trimethylaluminum, methyl aluminoxane, or activated zinc in the presence of sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBARF). The complex, (dppp)CoCl2, gives the best results (ratio of 1,2-to 1,4-addition >95:5) for a variety of linear terminal 1,3-dienes and 2-substituted 1,3-dienes. The [(PHOX)CoX2] (X = Cl, Br) complexes give mostly 1,4-addition with linear unsubstituted 1,3-dienes, but, surprisingly, selective 1,2-additions with 2-substituted or 2,3-disubstituted 1,3-dienes. Isolated and fully characterized (X-ray crystallography) Co(I)-complexes, (dppp)3Co2Cl2 and [(S,S)-BDPP]3Co2Cl2, do not catalyze the reaction unless activated by a Lewis acid or NaBARF, suggesting a key role for a cationic Co(I) species in the catalytic cycle. Regio- A nd enantioselective 1,2-hydroborations of 2-substituted 1,3-dienes are best accomplished using a catalyst prepared via activation of a chiral phosphinooxazoline-cobalt(II) complex with zinc and NaBARF. A number of common functional groups, among them,-OBn,-OTBS,-OTs, N-phthalimido-groups, are tolerated, and er's > 95:5 are obtained for several dienes including 1-alkenylcycloalk-1-enes. This operationally simple reaction expands the realm of asymmetric hydroboration to provide direct access to a number of nearly enantiopure homoallylic boronates, which are not readily accessible by current methods. The resulting boronates have been converted into the corresponding alcohols, potassium trifluororoborate salts, N-BOC amines, and aryl derivatives by C-BPin to C-aryl transformation.
Pd-catalyzed synthesis of α,β-unsaturated ketones by carbonylation of vinyl triflates and nonaflates
Zhang, Shaoke,Neumann, Helfried,Beller, Matthias
supporting information, p. 5938 - 5941 (2019/05/27)
A general and highly chemoselective Pd-catalyzed protocol for the synthesis of α,β-unsaturated ketones by carbonylation of vinyl triflates and nonaflates is presented. Applying the specific monophosphine ligand cataCXium A, the synthesis of various vinyl ketones as well as carbonylated natural product derivatives proceeds in good yields.
Mild Chemoenzymatic Oxidation of Allylic sec-Alcohols. Application to Biocatalytic Stereoselective Redox Isomerizations
Martínez-Montero, Lía,Gotor, Vicente,Gotor-Fernández, Vicente,Lavandera, Iván
, p. 2413 - 2419 (2018/03/13)
The design of catalytic oxidative methodologies in aqueous medium under mild reaction conditions and using molecular oxygen as final electron acceptor represents a suitable alternative to the traditional oxidative transformations. These methods are especially relevant if other functionalities that can be oxidized are present within the same molecule, as in the case of allylic alcohols. Herein we apply a simple chemoenzymatic system composed of the laccase from Trametes versicolor and 2,2,6,6-tetramethylpiperidinyloxy radical (TEMPO) to oxidize a series of racemic allylic sec-alcohols into the corresponding α,β-unsaturated ketones. Afterward, these compounds react with different commercially available ene-reductases to afford the corresponding saturated ketones. Remarkably, in the case of trisubstituted alkenes, the bioreduction reaction occurred with high stereoselectivity. Overall, a bienzymatic one-pot two-step sequential strategy has been described with respect to the synthesis of saturated ketones starting from racemic allylic alcohols, thus resembling the metal-catalyzed redox isomerizations of these derivatives that have been previously reported in the literature.
Hydration of aromatic terminal alkynes catalyzed by sulfonated condensed polynuclear aromatic (S-COPNA) resin in water
Tanemura, Kiyoshi,Suzuki, Tsuneo
supporting information, p. 955 - 958 (2017/02/18)
Hydration of aromatic terminal alkynes in the presence of a catalytic amount of sulfonated condensed polynuclear aromatic (S-COPNA) resin in water gave the corresponding methyl ketones in good yields. On the other hand, aliphatic terminal alkynes did not react at all under the employed conditions. Chemoselective hydration of aromatic terminal alkyne in the presence of aliphatic terminal alkyne catalyzed by S-COPNA resin was carried out.
