共查询到20条相似文献,搜索用时 31 毫秒
1.
N-Carbamoylimidazoles dissociate in solution to yield imidazole and an isocyanate that may be reacted with another aryl amine to form an unsymmetrical biaryl urea. This paper investigates the reaction kinetics and the influence of electron withdrawing/donating substituents on the reaction of N-carbamoylimidazoles with aniline. The overall reaction mechanism involves two zwitterionic intermediates, formed during dissociation and upon reaction of the liberated isocyanate with aniline. The rate limiting step for the reaction is a base catalysed proton transfer from the second zwitterionic intermediate. Although electron withdrawing substituents on the aryl group hinder dissociation, they significantly increase reaction rates compared to compounds bearing electron donating substituents. The imidazole liberated upon dissociation catalyses the rate determining step so that reactions of dissociated N-carbamoylimidazoles proceed more rapidly than those involving only isocyanates. In addition, the imidazole eliminates the need for anhydrous reaction conditions. The N-carbamoylimidazole methodology was demonstrated by preparing sorafenib, a biaryl urea kinase inhibitor, in good yield and excellent purity. 相似文献
2.
Takashi Harayama Akihiro Hori Georgeta Serban Yoshiaki Morikami Takuya Matsumoto Hitoshi Abe Yasuo Takeuchi 《Tetrahedron》2004,60(47):10645-10649
The total synthesis of luotonin A was achieved in excellent yield by using a Pd-assisted biaryl coupling reaction of N-(bromoquinolinyl)methylquinazolinone with Cy3P and KOAc. The successive treatment of luotonin A with NBS and aq. AgNO3 gave luotonin B in good yield. Although the Pd-assisted coupling reaction of N-(2-bromoindolyl)ethylquinazolinone with Cy3P and KOAc yielded rutaecarpine in poor yield, N-acetate under the same reaction conditions yielded the desired rutaecarpine directly in excellent yield. 相似文献
3.
Joachim J. Hug Nicolas A. Frank Christine Walt Petra enica Fabian Panter Rolf Müller 《Molecules (Basel, Switzerland)》2021,26(24)
Ribosomally synthesized and post-translationally modified peptides (RiPPs) are a structurally diverse group of natural products. They feature a wide range of intriguing post-translational modifications, as exemplified by the biarylitides. These are a family of cyclic tripeptides found in Planomonospora, carrying a biaryl linkage between two aromatic amino acids. Recent genomic analyses revealed that the minimal biosynthetic prerequisite of biarylitide biosynthesis consists of only one ribosomally synthesized pentapeptide precursor as the substrate and a modifying cytochrome-P450-dependent enzyme. In silico analyses revealed that minimal biarylitide RiPP clusters are widespread among natural product producers across phylogenetic borders, including myxobacteria. We report here the genome-guided discovery of the first myxobacterial biarylitide MeYLH, termed Myxarylin, from Pyxidicoccus fallax An d48. Myxarylin was found to be an N-methylated tripeptide that surprisingly exhibits a C–N biaryl crosslink. In contrast to Myxarylin, previously isolated biarylitides are N-acetylated tripeptides that feature a C–C biaryl crosslink. Furthermore, the formation of Myxarylin was confirmed by the heterologous expression of the identified biosynthetic genes in Myxococcus xanthus DK1622. These findings expand the structural and biosynthetic scope of biarylitide-type RiPPs and emphasize the distinct biochemistry found in the myxobacterial realm. 相似文献
4.
Kyoung Hoon Kim 《Tetrahedron》2004,60(41):9037-9042
Mono-N-alkylated octahydrobinaphthyl-2,2′-diamine (H8-BINAM) chiral ligands were employed in the catalytic and asymmetric oxidative coupling of methyl 3-hydroxy-2-naphthoate to the corresponding binaphthol derivative. The diamine ligand with one N-(3-pentyl) group shows highest enantioselectivity in the biaryl coupling among other BINAM derivatives, and the coupling reaction proceeds faster than the reactions using alkanediamine ligands. 相似文献
5.
Takashi Harayama Yuko Kawata Chie Nagura Tomonori Sato Taeko Miyagoe Hitoshi Abe Yasuo Takeuchi 《Tetrahedron letters》2005,46(36):6091-6094
This study investigated the effect of oxygen substituents in the benzoyl part of N-(2-iodophenyl)benzamide on the coupling position in its Pd-assisted biaryl coupling reaction. Benzamide with methylenedioxy and acyloxy groups yielded the ortho-product formed predominantly by connection to a more hindered carbon. The mechanism is discussed from the perspectives of both steric and coordinated effects. 相似文献
6.
Generating cis-aza-diaryl and triaryl ethers via organoBrønsted acid catalysed aza-Darzens chemistry
《Tetrahedron》2019,75(42):130532
We report the efficient combination of SNAr and organic Brønsted acid catalysis protocols for the construction of cis-aziridine-derived biaryl and triaryl ethers. Using aza-Darzens chemistry mono-cis-aziridine-biaryl and bis-(cis-aziridine)-triaryl ethers have been generated; these motifs have significant potential as easily synthesised, functionalised precursors of a glycopeptide backbone. 相似文献
7.
The indolo[2,1-a]isoquinoline and pyrrolo[2,1-a]isoquinoline nuclei have been synthesized from N-benzylindole or ethyl 1H-indol-1-ylacetate and N-benzylpyrrole precursors, respectively. Firstly, at C-2 of either the indole or pyrrole nucleus, aromatic rings containing a carbonyl substituent ortho to the newly formed biaryl axis were introduced using the Suzuki-Miyaura coupling reaction. Thereafter, under basic conditions the nucleophile that formed at the acidic methylene protons of the N-benzylindole, ethyl 1H-indol-1-ylacetate or N-benzylpyrrole intermediate reacted with the internal aromatic carbonyl to yield (after the expulsion of water) the title compounds. For example, exposure of ethyl 2-(2-(2-formylphenyl)-1H-indol-1-yl)acetate to potassium tert-butoxide resulted in the formation of ethyl indolo[2,1-a]isoquinoline-6-carboxylate. 相似文献
8.
Simon S. Moleele 《Tetrahedron》2008,64(46):10573-10580
Using tetralones as starting materials, the synthesis of biaryl compounds is described in this paper. The tetralones were initially converted into 1-bromo-3,4-dihydro-2-naphthalenecarbaldehydes before effecting aromatization into the corresponding naphthalenes. These products were then subjected to Suzuki-Miyaura cross-coupling reactions, with a variety of aromatic boronic acids containing substituents in the ortho position, to afford biaryl compounds. The biaryl compounds possess heteroatom containing substituents ortho to the newly formed biaryl axis. 相似文献
9.
A method for the high-yielding preparation of two tridentate, isoquinoline-derived ligands, involving successive Suzuki cross-coupling reactions, is described. The first ligand could be resolved via molecular complexation with N-benzylcinchonidinium chloride, while the second was resolved by chromatographic separation of its epimeric camphorsulfonates. The barrier to rotation about the central biaryl axis was evaluated via racemisation studies, and the absolute configuration assigned by X-ray crystallography. 相似文献
10.
Dr. Eric D. Slack Dr. Raina Seupel Prof. Dr. Donald H. Aue Prof. Dr. Gerhard Bringmann Prof. Dr. Bruce H. Lipshutz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(62):14237-14245
A stereoselective total synthesis of O,N-dimethylhamatine, an analogue of an axially chiral naphthylisoquinoline natural biaryl product from tropical Ancistrocladus lianas, is reported. The route features a late-stage atropo-diastereoselective biaryl bond formation. Generation of this especially challenging, sterically hindered tetra-ortho-substituted array was achieved by using Nolan's (IPr*NHC)PdCinCl pre-catalyst under mild Negishi coupling conditions. Discussion is offered regarding the selectivity obtained experimentally and predicted from DFT calculations on the key biaryl coupling step that leads to the desired M-diastereomer. 相似文献
11.
An asymmetric synthesis of (−)-N-acetylcolchinol is described based on a Suzuki-Miyaura coupling to generate the biaryl pharmacophore. The sole asymmetric centre was introduced by an asymmetric reduction of a dibenzosuberone derivative 24 using lithium borohydride in the presence of stoichiometric amounts of a chiral Lewis acid (TarB-NO2). A conjugate between an αVβ3 integrin-binding cyclic peptide c[RGDfK] and colchinol (adipoyl linker) was synthesised with an aim to deliver colchinol to solid tumours selectively. 相似文献
12.
Rajeshwar Reddy Aleti Alexey A. Festa Leonid G. Voskressensky Erik V. Van der Eycken 《Molecules (Basel, Switzerland)》2021,26(18)
Phenanthridinones are important heterocyclic frameworks present in a variety of complex natural products, pharmaceuticals and displaying wide range of pharmacological actions. Its structural importance has evoked a great deal of interest in the domains of organic synthesis and medicinal chemistry to develop new synthetic methodologies, as well as novel compounds of pharmaceutical interest. This review focuses on the synthesis of phenanthridinone scaffolds by employing aryl-aryl, N-aryl, and biaryl coupling reactions, decarboxylative amidations, and photocatalyzed reactions. 相似文献
13.
Rui-Juan Li Yu Zhao Harukuni Tokuda Xiao-Ming Yang Yue-Hu Wang Qian Shi Susan L. Morris-Natschke Hong-Xiang Lou Kuo-Hsiung Lee 《Tetrahedron letters》2014
A new and efficient total synthesis has been developed to obtain plagiochin G (22), a macrocyclic bisbibenzyl, and four derivatives. The key 16-membered ring containing biphenyl ether and biaryl units was closed via an intramolecular SNAr reaction. All synthesized macrocyclic bisbibenzyls inhibited Epstein–Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells and, thus, are potential cancer chemopreventive agents. 相似文献
14.
Extending the Substrate Scope of Bicyclic P‐Oxazoline/Thiazole Ligands for Ir‐Catalyzed Hydrogenation of Unfunctionalized Olefins by Introducing a Biaryl Phosphoroamidite Group
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Maria Biosca Dr. Alexander Paptchikhine Dr. Oscar Pàmies Prof. Pher G. Andersson Prof. Montserrat Diéguez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3455-3464
This study identifies a series of Ir‐bicyclic phosphoroamidite–oxazoline/thiazole catalytic systems that can hydrogenate a wide range of minimally functionalized olefins (including E‐ and Z‐tri‐ and disubstituted substrates, vinylsilanes, enol phosphinates, tri‐ and disubstituted alkenylboronic esters, and α,β‐unsaturated enones) in high enantioselectivities (ee values up to 99 %) and conversions. The design of the new phosphoroamidite–oxazoline/thiazole ligands derives from a previous successful generation of bicyclic N‐phosphane–oxazoline/thiazole ligands, by replacing the N‐phosphane group with a π‐acceptor biaryl phosphoroamidite moiety. A small but structurally important family of Ir‐phosphoroamidite–oxazoline/thiazole precatalysts has thus been synthesized by changing the nature of the N‐donor group (either oxazoline or thiazole) and the configuration at the biaryl phosphoroamidite moiety. The substitution of the N‐phosphane by a phosphoroamidite group in the bicyclic N‐phosphane–oxazoline/thiazole ligands extended the range of olefins that can be successfully hydrogenated. 相似文献
15.
The first and enantioselective total synthesis of the heterodimeric biaryl antifungal natural product parnafungin A1 as well as complex biaryl tetrahydroxanthone 10a-epi-hirtusneanine is accomplished, by employing cross-coupling through the benzoxaborole strategy to construct their sterically hindered biaryl cores. Besides the powerful Suzuki–Miyaura cross-coupling, the synthesis of parnafungin A1 also features a highly diastereoselective oxa-Michael addition to construct a tetrahydroxanthone skeleton, and an effective Zn-mediated reductive cyclization-Mitsunobu sequence to furnish the isoxazolidinone structure. Key innovations in total synthesis of 10a-epi-hirtusneanine include the employment of DTBS protection for functional group manipulation on the tetrahydroxanthone skeleton, stereoselective methylations, and complete reversal of the stereochemistry of the C5-hydroxy group using oxidation/Evans–Saksena reduction, as well as the strategy of preparing both complex tetrahydroxanthone monomers from the same chiral intermediate 25.The first, enantioselective total synthesis of the heterodimeric biaryl antifungal natural product parnafungin A1 as well as 10a-epi-hirtusneanine is accomplished, using a cross-coupling strategy to construct their sterically hindered biaryl cores. 相似文献
16.
Jessica Margalef Matteo Lega Francesco Ruffo Oscar Pàmies Montserrat Diéguez 《Tetrahedron: Asymmetry》2012,23(13):945-951
Eight (biaryl)phosphite/pyridine ligands 1–2a–d have been prepared by the modular functionalization of positions C-2 and C-3 of two d-glucopyranoside backbones. The chiral ligands were examined in the iridium-catalyzed asymmetric hydrogenation of poorly functionalized alkenes, as a function of the relative position of the coordinating groups and the geometric properties of the biaryl phosphite moieties. Enantiomeric excesses of up to 90% were achieved in the hydrogenation of E-2-(4-methoxyphenyl)-2-butene by using 1a and 1c, which seemingly combine the beneficial effect of the phosphite at the 2-position with the matching (Rax)-configuration of their encumbered biaryl substituents. The results of the hydrogenation of more challenging substrates, such as Z-trisubstituted alkenes, alkenes with a neighboring polar group or demanding 1,1-di-substituted alkenes, generally confirmed this trend, and in some significant cases, the chiral hydrogenated products were isolated with ees of 65–79%. 相似文献
17.
《Tetrahedron: Asymmetry》2006,17(5):767-777
The synthesis of novel C2-symmetric bisoxazoline ligands with an axial-unfixed biaryl backbone and different substituents at the oxazoline ring is reported. The diastereomer equilibrium of these ligands in solution and their complexation behavior with the copper(I) ion were studied. Their application in Cu-catalyzed cyclopropanation of styrene, with diazoacetate, was carried out and the effects of the biaryl backbone and the substituent on the oxazoline ring in the catalysis were examined. The best result was obtained with the ligand having a 1,1′-binaphthyl backbone and a t-butyl group on the oxazoline ring, which afforded 89% de and 96% de for the trans- and cis-products of the above asymmetric cyclopropanation reaction, respectively. 相似文献
18.
Dr. Tomoyuki Ikai Dr. Masaki Ito Dr. Kosuke Oki Dr. Nozomu Suzuki Prof. Eiji Yashima 《Angewandte Chemie (International ed. in English)》2023,62(31):e202306252
A series of poly(biarylylacetylene)s (PBAs) bearing axially-chiral (S)-and (R)-pyridyl-N-oxide residues with a methoxy, propoxy, or acetyloxy substituent at the 3-position of the biaryl units was synthesized. All the PBAs formed a preferred-handed helix, while the helical sense preference was varied depending on the substituents despite the same twist-sense of the biaryl units. Among them, the propoxy-bound helical PBA showed an exceptionally high chiral recognition ability as a chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) and efficiently resolved not only various chiral aromatic alcohols, but also a variety of chiral aliphatic alcohols; the latter still remains difficult to resolve by commercially-available CSPs in HPLC. Such practically-useful both handed helical PBA-based CSPs can be produced from the racemic PBA composed of fully racemic monomer units through deracemization of the biaryl units with a chiral alcohol. 相似文献
19.
Colin Baillie 《Tetrahedron》2004,60(19):4159-4168
Monodentate, biphenyl-type phosphines have emerged as a powerful class of ligands in homogeneous catalysis. Synthetic methods for these ligands are limited, however. We report that the palladium-catalysed Suzuki coupling of OPR2(o-C6H4X) (R=Ph, t-Bu; X=Br, I) with arylboronic acids affords a variety of biaryl phosphine oxides including those that contain heterocycles. The corresponding phosphines are readily obtained by treatment with HSiCl3. The methodology provides an easy entry to monodentate biaryl and heterobiaryl P?X (X=N, O, S) phosphines with diverse steric and electronic properties. 相似文献
20.
Tomoyuki Esumi 《Tetrahedron letters》2004,45(37):6941-6945
Isoplagiochin D, a highly strained macrocyclic bis(bibenzyls) with two biaryl units isolated from the liverwort Pladiochila fruticosa, was prepared in 10.6% overall yield for the 11 steps by an efficient synthetic approach involving the construction of two bibenzyl and one biaryl units using Horner-Wadsworth-Emmons and Suzuki-Miyaura protocols. 相似文献