173277-75-3Relevant academic research and scientific papers
Cobalt-Catalyzed Cross-Couplings between Alkenyl Acetates and Aryl or Alkenyl Zinc Pivalates
Li, Jie,Knochel, Paul
supporting information, p. 11436 - 11440 (2018/08/11)
CoBr2 (5 mol %) in the presence of 2,2′-bipyridyl (5 mol %) enables electrophilic alkenylations between easily accessible alkenyl acetates or tosylates and various functionalized aryl zinc pivalates at ambient temperature. This cobalt-catalyzed
Revisitation of Organoaluminum Reagents Affords a Versatile Protocol for C-X (X = N, O, F) Bond-Cleavage Cross-Coupling: A Systematic Study
Ogawa, Hiroyuki,Yang, Ze-Kun,Minami, Hiroki,Kojima, Kumiko,Saito, Tatsuo,Wang, Chao,Uchiyama, Masanobu
, p. 3988 - 3994 (2017/06/19)
A revisit of organoaluminum reagents for cross-coupling reactions has opened up several types of C-C bond formation protocols through cleavage of phenolic/alcoholic C-O and C-F and ammonium C-N bonds. Catalyzed by the commercially available NiCl2(PCy3)2 catalyst, these reactions proceed smoothly with a wide range of substrates and broad functional group compatibility, providing a versatile methodology for organoaluminum-mediated cross-coupling processes.
Iron-Catalyzed Cross-Coupling of Alkenyl Acetates
G?rtner, Dominik,Stein, André Luiz,Grupe, Sabine,Arp, Johannes,Von Wangelin, Axel Jacobi
supporting information, p. 10545 - 10549 (2015/09/02)
Stable C-O linkages are generally unreactive in cross-coupling reactions which mostly employ more electrophilic halides or activated esters (triflates, tosylates). Acetates are cheap and easily accessible electrophiles but have not been used in cross-couplings because the strong C-O bond and high propensity to engage in unwanted acetylation and deprotonation. Reported herein is a selective iron-catalyzed cross-coupling of diverse alkenyl acetates, and it operates under mild reaction conditions (0 C, 2 h) with a ligand-free catalyst (1-2 mol%). Iron clad: Acetates are underutilized electrophiles in metal-catalyzed cross-coupling reactions because of the strong alkenyl C-O bond and their propensity to engage in unwanted reactions. Combination of a ligand-free low-valent Fe catalyst with nucleophilic organomagnesium reagents, low temperature, and short reaction times results in highly selective cross-couplings with alkenyl acetates.
Catalytic enantioselective nazarov cyclization: Construction of vicinal all-carbon-atom quaternary stereocenters
Jolit, Anais,Walleser, Patrick M.,Yap, Glenn P. A.,Tius, Marcus A.
supporting information, p. 6180 - 6183 (2014/06/23)
The diastereoselective asymmetric synthesis of vicinal all-carbon-atom quaternary stereocenters is a challenging problem in organic synthesis for which only few solutions have been described. A catalytic asymmetric Nazarov cyclization of fully substituted dienones that provides cyclopentenone derivatives with vicinal quaternary stereocenters in high optical purity and as single diastereoisomers is now reported.
A versatile palladium catalyst system for Suzuki-Miyaura coupling of alkenyl tosylates and mesylates
Wong, Pui Yu,Chow, Wing Kin,Chung, Kin Ho,So, Chau Ming,Lau, Chak Po,Kwong, Fuk Yee
supporting information; experimental part, p. 8328 - 8330 (2011/09/14)
A general and effective palladium system for Suzuki-Miyaura coupling of alkenyl electrophiles under mild reaction conditions is reported. With the Pd(OAc)2/CM-phos system, a variety of alkenyl tosylates are coupled well with ArB(OH)2. Moreover, the first successful examples of using alkenyl mesylates in alkenylation are also described.
Selective iron-catalyzed cross-coupling reactions of Grignard reagents with enol triflates, acid chlorides, and dichloroarenes
Scheiper, Bodo,Bonnekessel, Melanie,Krause, Helga,Fuerstner, Alois
, p. 3943 - 3949 (2007/10/03)
Cheap, readily available, air stable, nontoxic, and environmentally benign iron salts such as Fe(acac)3 are excellent precatalysts for the cross-coupling of Grignard reagents with alkenyl triflates and acid chlorides. Moreover, it is shown that dichloroarene and -heteroarene derivatives as the substrates can be selectively monoalkylated by this method. All cross-coupling reactions proceed very rapidly under notably mild conditions and turned out to be compatible with a variety of functional groups in both reaction partners. A detailed analysis of the preparative results suggests that iron-catalyzed C-C bond formations can occur via different pathways. Thus, it is likely that reactions of methylmagnesium halides involve iron-ate complexes as the active components, whereas reactions of Grignard reagents with two or more carbon atoms are effected by highly reduced iron-clusters of the formal composition [Fe(MgX)2]n generated in situ. Control experiments using the ate-complex [Me4Fe]Li2 corroborate this interpretation.
Alternatives to vinyl triflates for cross-coupling with arylboronic acids
Huffman, Mark A.,Yasuda, Nobuyoshi
, p. 471 - 473 (2007/10/03)
Vinyl phosphates, mesylates, and tosylates derived from 1,3-dicarbonyl compounds are coupled with phenylboronic acid using nickel or palladium catalysts. An application to the area of 2-aryl carbapenem antibiotics is demonstrated. Alternative conditions for the nickel-catalyzed coupling of aryl mesylates are also reported.
The reaction of α-diazo-β-hydroxy esters with boron trifluoride etherate: Generation and rearrangement of destabilized vinyl cations. A detailed experimental and theoretical study
Pellicciari, Roberto,Natalini, Benedetto,Sadeghpour, Bahman M.,Marinozzi, Maura,Snyder, James P.,Williamson, Bobby L.,Kuethe, Jeffrey T.,Padwa, Albert
, p. 1 - 12 (2007/10/03)
Cyclic ethyl 2-diazo-3-hydroxy carboxylates were prepared by treating ethyl diazoacetate with LDA followed by reaction with a series of cyclic ketones. Further treatment of these α-diazo-β-hydroxy esters with boron trifluoride etherate in various solvents affords an unusual array of products. Product types and ratios were found to be strongly dependent on ring size and the solvent used. The reaction proceeds by Lewis acid complexation of the alcohol functionality of the diazo hydroxy ester with BF3 etherate followed by neighboring-group participation of the diazo moiety to generate a cycloalkylidene diazonium salt. Loss of nitrogen produces a highly reactive, destabilized, linear vinyl cation. Ring expansion via a 1,2-methylene shift leads to the formation of a more stable, bent cycloalkenyl vinyl cation. A subsequent 1,2-methylene shift results in ring contraction ultimately leading to a stable allylic cation. This cation is either trapped by the solvent or else undergoes cyclization with the adjacent ester group to give a lactone. Computational studies at the 6-31G* level were performed to determine the geometry of the optimized vinyl cations. Relative energies suggest a moderate energy gain for isomerization of the initial vinyl cation V1 to the rearranged vinyl cation V2 followed by a large stabilization in energy for subsequent conversion to the allyl cation A1. Compared with isolated product distributions, the energy profiles suggest kinetically-controlled V1 → V2 → A1 migrations. Finally, the calculations suggest that in diethyl ether the carbocations may be coordinated to a molecule of solvent resulting in "protected" cationic intermediates with nonlinear geometries.
Design and synthesis of ring-constrained boropeptide thrombin inhibitors
Fevig,Abelman,Brittelli,Kettner,Knabb,Weber
, p. 295 - 300 (2007/10/03)
Ring-constrained boropeptide thrombin inhibitors were designed using information from the X-ray crystal structure of 1 (3-phenylpropionyl-Pro-boroLys-OH · HCl) bound to thrombin. The constraints utilized cyclohexane and pyrrolidine rings to preorganize an aromatic ring in an orientation allowing optimum edge-to-face interaction with the tryptophan 215 side chain located in the S3 specificity pocket of thrombin.
