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1.
Modular Stereoselective Synthesis of (1→2)‐C‐Glycosides based on the sp2–sp3 Suzuki–Miyaura Reaction
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Beata Oroszova Jan Choutka Dr. Radek Pohl Dr. Kamil Parkan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7043-7047
This work reports a modular and rapid approach to the stereoselective synthesis of a variety of α‐ and β‐(1→2)‐linked C‐disaccharides. The key step is a Ni‐catalyzed cross‐coupling reaction of D ‐glucal pinacol boronate with alkyl halide glycoside easily prepared from commercially available D ‐glucal. The products of this sp2–sp3 cross‐coupling reaction can be converted to glucopyranosyl, mannopyranosyl, or 2‐deoxy‐glucopyranosyl C‐mannopyranosides by one‐ or two‐step stereoselective oxidative–reductive transformations. To the best of our knowledge, we demonstrated the first synthetic application of a challenging sp2–sp3 Suzuki‐Miyaura cross‐coupling reaction in carbohydrate chemistry. 相似文献
2.
Stereocontrolled Synthesis of Vinyl Boronates and Vinyl Silanes via Atom‐Economical Ruthenium‐Catalyzed Alkene–Alkyne Coupling
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Prof. Dr. Barry M. Trost Dr. Dennis C. Koester Alastair N. Herron 《Angewandte Chemie (International ed. in English)》2015,54(52):15863-15866
The synthesis of vinyl boronates and vinyl silanes was achieved by employing a Ru‐catalyzed alkene–alkyne coupling reaction of allyl boronates or allyl silanes with various alkynes. The double bond geometry in the generated vinyl boronates can be remotely controlled by the juxtaposing boron‐ and silicon groups on the alkyne substrate. The synthetic utility of the coupling products has been demonstrated in a variety of synthetic transformations, including iterative cross‐coupling reactions, and a Chan‐Lam‐type allyloxylation followed by a Claisen rearrangement. A sequential one‐pot alkene‐alkyne‐coupling/allylation‐sequence with an aldehyde to deliver a highly complex α‐silyl‐β‐hydroxy olefin with a handle for further functionalization was also realized. 相似文献
3.
《Magnetic resonance in chemistry : MRC》2003,41(12):1015-1020
Complex formation between N‐butylboronic acid and D ‐(+)‐glucose, D ‐(+)‐mannose, methyl‐α‐D ‐glucopyranoside, methyl‐β‐D ‐galactopyranoside and methyl α‐D ‐mannopyranoside under neutral conditions was investigated by 1H, 13C and 11B NMR spectroscopy and gas chromatography–mass spectrometry (GC–MS) D ‐(+)‐Glucose and D ‐(+)‐mannose formed complexes where the boronates are attached to the 1,2:4,6‐ and 2,3:5,6‐positions of the furanose forms, respectively. On the other hand, the boronic acid binds to the 4,6‐positions of the two methyl derivatives of glucose and galactose. Methyl α‐D ‐mannopyranoside binds two boronates at the 2,3:4,6‐positions. 11B NMR was used to show the ring size of the complexed sugars and the boronate. GC–MS confirmed the assignments. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
4.
Jack Chang Hung LeeDennis G. Hall 《Tetrahedron letters》2011,52(2):321-324
Gold (I) complexes generated from a mixture of gold and silver salts were found to be highly reactive for the cycloisomerization reactions of boronated enynes. Both alkynyl pinacol boronates and alkenyl pinacol boronates were tolerated, affording products in moderate to high yields. Interestingly, the ratio of the different endo- and exo-products was heavily dependent on the position of the boronate functionality. Further applications including Suzuki-Miyaura cross coupling and oxidation reactions could be carried out, affording a variety of synthetically useful products. 相似文献
5.
Expedient Synthesis of Chiral α‐Amino Acids through Nickel‐Catalyzed Reductive Cross‐Coupling
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Xi Lu Jun Yi Zhen‐Qi Zhang Jian‐Jun Dai Jing‐Hui Liu Prof. Bin Xiao Prof. Yao Fu Prof. Lei Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15339-15343
A novel method for the synthesis of non‐natural L ‐ and D ‐amino acids by a Ni‐catalyzed reductive cross‐coupling reaction is described. This strategy enables the racemization‐free cross‐coupling of serine/homoserine‐ derived iodides with aryl/acyl/alkyl halides. It provides convenient access to varieties of enantiopure and functionalized amino acids, which are important building blocks in bioactive compounds and pharmaceuticals. 相似文献
6.
Reaction Optimization,Scalability, and Mechanistic Insight on the Catalytic Enantioselective Desymmetrization of 1,1‐Diborylalkanes via Suzuki–Miyaura Cross‐Coupling
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Ho‐Yan Sun Koji Kubota Prof. Dennis G. Hall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):19186-19194
A method for enantioselective desymmetrization of 1,1‐diborylalkanes through a stereoselective Pd‐catalyzed Suzuki–Miyaura cross‐coupling has been thoroughly optimized. The most effective ligand was found to be a α,α,α,α‐tetra‐aryl‐1,3‐dioxolane‐4,5‐dimethanol (TADDOL)‐derived phosphoramidite. Results show that in order to achieve high selectivity, a suitable balance between the sterics of the aryl groups and the amino group on the ligand must be achieved. While the base has been known to facilitate transmetallation in cross‐coupling reactions, mechanistic studies on this desymmetrization process reveal that the base, in the presence of KHF2, likely plays an additional role in the hydrolysis of the pinacol boronates to the corresponding boronic acids. Through an in depth optimization of the chiral ligand and mechanistic studies, it was possible to obtain ee values over 90 % for several aryl bromides and to develop a reliably scalable process (up to one gram of 1,1‐diborylalkane substrate). 相似文献
7.
Junyu Dong Tianbin Li Chuan Dai Wen Weng Xinghua Xue Yuyu Zhang Qingle Zeng 《应用有机金属化学》2013,27(6):337-340
A straightforward, protecting‐group‐free protocol for the synthesis of chiral 6‐substituted and 6,6’‐disubstituted binols (binol = 1,1’‐bi‐2‐naphthol) by palladium‐catalyzed hydroxylation, C–N and C–O coupling of chiral 6‐bromo‐ and 6,6’ ‐dibromo‐1,1’‐binaphthols is developed. The protecting group free palladium‐catalyzed hydroxylation, C–O and C–N cross‐coupling protocol affords a straightforward and general method for the synthesis of chiral 6‐substituted and 6,6’‐disubstituted binols with good yields, avoiding the tedious procedures of introduction and removal of protecting groups. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
8.
A General Palladium‐Catalyzed Hiyama Cross‐Coupling Reaction of Aryl and Heteroaryl Chlorides
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Dr. On Ying Yuen Dr. Chau Ming So Ho Wing Man Prof. Fuk Yee Kwong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(19):6471-6476
A general palladium‐catalyzed Hiyama cross‐coupling reaction of aryl and heteroaryl chlorides with aryl and heteroaryl trialkoxysilanes by a Pd(OAc)2/ L2 catalytic system is presented. A newly developed water addition protocol can dramatically improve the product yields. The conjugation of the Pd/ L2 system and the water addition protocol can efficiently catalyze a broad range of electron‐rich, ‐neutral, ‐deficient, and sterically hindered aryl chlorides and heteroaryl chlorides with excellent yields within three hours and the catalyst loading can be down to 0.05 mol % Pd for the first time. Hiyama coupling of heteroaryl chlorides with heteroaryl silanes is also reported for the first time. The reaction can be easily scaled up 200 times (100 mmol) without any degasification and purification of reactants; this facilitates the practical application in routine synthesis. 相似文献
9.
Reaction of (diisopropylamino)chloroboryl ethers of alkynols with alkynylstannanes in the presence of nickel catalysts afforded formal trans-alkynylboration products in good yields. The products were isolated as pinacol boronates after treatment of the crude reaction mixture with acetic anhydride and pinacol in the presence of a base. The trans-alkynylboration products underwent Suzuki-Miyaura coupling reaction with organic halides. A 2-borylalkenylnickel(II) complex, in which the boryl and nickel groups are located in a trans fashion, was isolated in a reaction of the chloroboryl ether with a single equivalent of a nickel(0)-phosphine complex. 相似文献
10.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(39):12148-12151
Trifluoromethoxy‐substituted stereogenic centers can be constructed with high enantioselectivity by a nickel‐catalyzed Suzuki–Miyaura coupling of readily available α‐bromobenzyl trifluoromethyl ethers with a variety of aryl pinacol boronates. The coupling proceeds under mild reaction conditions, and a variety of common functional groups, such as fluoride, chloride, bromide, ester, enolizable ketone, nitro, cyano, amino, and vinyl moieties, were well tolerated. Furthermore, the reaction can be easily scaled up to gram quantities without a decrease in enantioselectivity. 相似文献
11.
Synthesis of Aminoboronic Acid Derivatives from Amines and Amphoteric Boryl Carbonyl Compounds
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Diego B. Diaz Dr. Conor C. G. Scully Sean K. Liew Dr. Shinya Adachi Dr. Piera Trinchera Dr. Jeffrey D. St. Denis Prof. Dr. Andrei K. Yudin 《Angewandte Chemie (International ed. in English)》2016,55(41):12659-12663
Herein, we demonstrate the use of α‐boryl aldehydes and acyl boronates in the synthesis of aminoboronic acid derivatives. This work highlights the untapped potential of boron‐substituted iminium ions and offers insights into the behavior of N‐methyliminodiacetyl (MIDA) boronates during condensation and tautomerization processes. The preparative value of this contribution lies in the demonstration that various amines, including linear and cyclic peptides, can be readily conjugated with boron‐containing fragments. A mild deprotection of amino MIDA‐boronates enables access to α‐ and β‐aminoboronic acids in high chemical yields. This simple process should be applicable to the synthesis of a wide range of bioactive molecules as well as precursors for cross‐coupling reactions. 相似文献
12.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(4):1041-1045
An efficient synthesis of biaryls through a gold‐catalyzed oxidative cross‐coupling of arenes with strong electron‐deprived aryl boronates is presented herein. Regio‐ and chemocontrol are achieved by the selective activation of these coupling partners by gold at different oxidation states. Under reaction conditions devoid of basic additives or directing groups, the role of acetato ligand as an internal base has been revealed as a key parameter for expanding the reaction scope in these transformations. 相似文献
13.
D‐Glucosamine in iron‐catalysed cross‐coupling reactions of Grignards with allylic and vinylic bromides: application to the synthesis of a key sitagliptin precursor
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A sustainable D ‐glucosamine ligand is successfully introduced into iron‐catalysed C ? C cross‐coupling reactions for the first time. The Fe(acac)2/D ‐glucosamine·HCl/Et3N catalytic system was effective at 5 mol% loading in coupling reactions of Grignard reagents with organic bromides. Moderate to high efficiency was achieved with preserved stereochemistry when allyl (Csp3) or alkenyl (Csp2) bromides were coupled with phenylmagnesium (Csp2) or benzylmagnesium (Csp3) bromides. The catalytic system developed was also successfully applied for the novel and economic preparation of a Michael‐acceptor‐like starting material used in an alternative synthesis of the drug sitagliptin, a known blockbuster for the treatment of type II diabetes mellitus. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
14.
A highly selective synthesis of 1‐substituted (E)‐buta‐1,3‐dienes with 4,4,5,5‐tetramethyl‐2‐vinyl‐1,3,2‐dioxaborolane as building block
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Justyna Szudkowska‐Frątczak Aline Ryba Adrian Franczyk Jędrzej Walkowiak Maciej Kubicki Piotr Pawluć 《应用有机金属化学》2014,28(3):137-139
Highly selective synthesis of 1‐substituted (E)‐buta‐1,3‐dienes via palladium‐catalyzed Suzuki–Miyaura cross‐coupling of (E)‐alkenyl iodides with 4,4,5,5‐tetramethyl‐2‐vinyl‐1,3,2‐dioxaborolane ( 1 ) is reported. The vinylboronate pinacol ester ( 1 ) acts as a vinyl building block to show high chemoselectivity for the Suzuki–Miyaura pathway versus Heck coupling in the presence of biphasic conditions (Pd(PPh3)4, aqueous K2CO3, toluene and ethanol). Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
15.
A new catalytic retro‐pinacol/cross‐pinacol reaction, followed by subsequent rearrangement or deoxygenation of the intermediately formed vicinal diols, is described. This operationally simple one‐pot protocol allows isolation of geminal α,α‐diphenyl ketones or 1,1‐diphenyl alkenes with high yields and selectivities. 相似文献
16.
A simple,quick and novel protocol for biaryl synthesis using LiCl‐promoted in situ‐generated Pd nanoparticles
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Parmita Phukan Preeti Rekha Boruah Praveen Singh Gehlot Arvind Kumar Diganta Sarma 《应用有机金属化学》2018,32(2)
This paper describes a simple and a very quick protocol for biaryl synthesis using the Suzuki–Miyaura cross‐coupling reaction. A quintessential role of salting‐out agent LiCl was observed in the Suzuki–Miyaura cross‐coupling reaction that enhanced the reduction rate of Pd (II) to a considerable extent, resulting in the formation of nanosized palladium in a few seconds. The isolated Pd nanoparticles were characterized with X‐ray diffraction, dynamic light scattering, TGA, transmission electron microscopy and scanning electron microscopy‐dispersive X‐ray spectroscopy. The Suzuki–Miyaura cross‐coupling reaction proceeded very well with the in situ‐generated Pd nanocatalysts furnishing the desired biaryl adducts with excellent yields. 相似文献
17.
Yao Zhang Bo Han Shaolin Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(39):13998-14002
The direct and selective functionalization of relatively simple and readily accessible precursors to produce highly functionalized alkyl boronates is a synthetically useful process. Herein we report a NiH‐catalyzed remote hydroarylation process that can, through a synergistic combination of chain walking and subsequent cross‐coupling, introduce an aryl group at the adjacent carbon atom of alkyl boronates under mild conditions. By means of a preliminary experiment with moderate enantioselectivity, it was shown that an asymmetric version could also be realized. 相似文献
18.
Methionine: a green and efficient promoter for copper‐catalyzed Sonogashira cross‐coupling reactions
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In the presence of amino acids as environmentally friendly ligands, CuI‐catalyzed Sonogashira cross‐coupling of various aryl halides with phenylacetylene was conducted to afford the corresponding internal alkynes. l ‐Methionine was found to be useful for this palladium‐free and amine‐free coupling reaction. It was also found that the solvent system plays an important role in this reaction, and significantly affects the product formation and reaction rate. Sonogashira coupling of aryl iodides and aryl bromides in dimethylsulfoxide or dimethylformamide gave the coupled products in good to excellent yields. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
19.
Synthesis of Heterodinuclear Hemisalen Complexes on a Hexaarylbenzene Scaffold and their Application for the Cross‐Pinacol Coupling Reaction
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Akihiro Miyasaka Dr. Toru Amaya Prof. Toshikazu Hirao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1615-1621
Intermolecular cross‐pinacol coupling reaction between aliphatic and aromatic aldehydes by using heterodinuclear hemisalen complexes 1 cis with vanadium(V) and titanium(IV) on a hexaarylbenzene scaffold is reported. Our ligand design is based on the individual activation of two aldehydes by vanadium and titanium, which are positioned with a suitable space on the rigid scaffold. Ligands such as 1 cis were synthesized by Diels–Alder addition and decarbonylation reaction, followed by condensation of dialdehyde 3 cis with various aminophenols. The influence of the substituents on the ligands on the pinacol coupling reaction was investigated. As a result, the reductive coupling reaction between aliphatic and aromatic aldehydes by using a catalytic amount of 1 cis in the presence of Me3SiCl and Zn provided the corresponding cross‐coupled 1,2‐diol in good yields with high cross‐selectivity. 相似文献
20.
Luísa R. Carvalho Marta C. Corvo Ramu Enugala M. Manuel B. Marques Eurico J. Cabrita 《Magnetic resonance in chemistry : MRC》2010,48(4):323-330
The solid‐phase synthesis (SPS) of a structurally complex glycopeptide, using Sieber amide resin, was monitored by high resolution magic angle spinning NMR, demonstrating the further application of this technique. A synthetic peptidoglycan derivative, a precursor of a biologically active PGN, known to be involved in the cellular recognition, was prepared by SPS. The synthesis involved the preparation of an N‐alloc glucosamine moiety and the synthesis of a simple amino acid sequence L ‐Ala‐D ‐Glu‐L ‐Lys‐D ‐Ala‐D ‐Ala. Last step consisted the coupling, on solid‐phase, of the protected muramyl unit to the peptide chain. Proton spectra with good suppression of the polystyrene signals in swollen resin samples were obtained in DMF‐d7 as a solvent and by using a nonselective 1D TOCSY/DIPSI‐2 scheme, thus allowing to follow the SPS without losses of compound and cleavage from the resin. The assignment of the proton spectra of the resin‐bound amino acid sequence and of the bound glycopeptide was achieved through the combination of MAS COSY, TOCSY and NOESY. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献