- Air-stable Pd(0) catalyst bearing dual phosphine ligands: a detailed evaluation of air stability and catalytic property in cross-coupling reactions
-
We have synthesised an air-stable Pd(0) catalyst bearing donor and acceptor phosphine ligands (Complex1). This study revealed the long-term air stability and catalytic property of Complex1as a catalyst for cross-coupling reactions, where it was stable in air for eight months. DFT calculations revealed that the acceptor ligands in Complex1decreased the HOMO energy level, which provided the observed air stability. Complex1successfully served as a catalyst for direct C-H arylation reactions and Suzuki-Miyaura cross-coupling reactions, and catalysed the reaction of a relatively inactive substrate, 2-chrolopyridine, which could not be achieved by conventional, air-stable Pd(0) catalysts. Isolating the intermediates of the coupling reactions revealed that each intermediate possessed the donor ligand (PCy3), which was determined to be responsible for imparting the high catalytic activity exhibited by Complex1.
- Sato, Ryota,Kanbara, Takaki,Kuwabara, Junpei
-
p. 12814 - 12819
(2020/10/02)
-
- A convenient reagent for the conversion of aldoximes into nitriles and isonitriles
-
For the dehydroxylation of aldoximes with 4-nitro-1-((trifluoromethyl)sulfonyl)-imidazole (NTSI), slight modifications of reaction conditions resulted in significantly different reaction paths to provide either nitriles or isonitriles. The challenging conversion of aldoximes into isonitriles was achieved under mild conditions.
- Zhang, Wei,Lin, Jin-Hong,Zhang, Pengfei,Xiao, Ji-Chang
-
supporting information
p. 6221 - 6224
(2020/06/29)
-
- Direct Synthesis of Nitriles from Aldehydes Using an O-Benzoyl Hydroxylamine (BHA) as the Nitrogen Source
-
The direct synthesis of nitriles from commercially available or easily prepared aldehydes has been achieved. O-(4-CF3-benzoyl)-hydroxylamine (CF3-BHA) was utilized as the nitrogen source to generate O-acyl oximes in situ with aldehydes, which can be converted to a nitrile with the assistance of a Bronsted acid. Several aliphatic, aromatic, and α,β-unsaturated nitriles that contain different functional groups were prepared in high yields (up to 94% yield). This method has notable advantages, such as simple and mild conditions, high yields, and good functional group tolerance.
- An, Xiao-De,Yu, Shouyun
-
supporting information
p. 5064 - 5067
(2015/11/03)
-
- In-Depth Assessment of the Palladium-Catalyzed Fluorination of Five-Membered Heteroaryl Bromides
-
A thorough investigation of the challenging Pd-catalyzed fluorination of five-membered heteroaryl bromides is presented. Crystallographic studies and density functional theory (DFT) calculations suggest that the challenging step of this transformation is
- Milner, Phillip J.,Yang, Yang,Buchwald, Stephen L.
-
supporting information
p. 4775 - 4780
(2015/10/28)
-
- Practical synthesis of aromatic nitriles via gallium-catalysed electrophilic cyanation of aromatic C-H bonds
-
A gallium-catalysed, direct cyanation reaction of aromatic and heteroaromatic C-H bonds with cyanogen bromide was developed as a practical synthetic method for the preparation of aromatic nitriles. The Royal Society of Chemistry 2012.
- Okamoto, Kazuhiro,Watanabe, Masahito,Murai, Masahito,Hatano, Ryo,Ohe, Kouichi
-
supporting information; experimental part
p. 3127 - 3129
(2012/04/23)
-
- Photochromic properties of terarylene derivatives having a π-conjugation unit on central aromatic ring
-
A series of terarylenes based on 4,5-bisbenzothienylthiazole have been synthesized, and their photochromic properties are studied both in solution and in the crystalline state. The substitution effect of the central aromatic ring on the photochromic reactivity were also studied. The introduction and expansion of the π-conjugated system at the 2-position of the thiazole ring led to a red-shift of the absorption peaks for both open- and closed-ring isomers of terarylenes. 2-Hydro and 2-phenyl derivatives of 4,5-bisbenzothienylthiazoles displayed a photochromic reaction, even in the single-crystal state. X-Ray crystal analysis showed their molecular structure to have quasi-C2 symmetry, suggesting significant CH...N and CH...S interactions. Although the 2-hydro and 2-phenyl derivatives exhibited high photocyclization reaction quantum yields over 0.5, the 2-phenylthienyl derivative showed a considerably smaller reactivity, even though it is supposed to have a similar conformation to those of the other two derivatives. Meanwhile, these molecules showed similar photocycloreversion quantum yields as high as 0.3. The relationship between their electronic structures and photochromic reactivity is also discussed by means of quantum chemical calculations. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009.
- Kutsunugi, Yuichiro,Kawai, Shigekazu,Nakashima, Takuya,Kawai, Tsuyoshi
-
experimental part
p. 1368 - 1373
(2009/09/24)
-
- Aryl triflates: Useful coupling partners for the direct arylation of heteroaryl derivatives via Pd-catalyzed C-H activation-functionalization
-
Aryl triflates were found to be suitable partners for the palladium catalyzed direct arylation of heteroaromatics via C-H activation- functionalization. The reaction conditions and the catalyst have a determining influence on the yields. The system combining PPh3 and Pd(OAc) 2 using KOAc as base and DMF as solvent promotes the selective 2- or 5-arylations in moderate to high yields. Several heteroaromatics such as furan, thiophene, thiazole or oxazole derivatives have been employed successfully. The electronic properties of the aryl triflates also have a decisive influence on the yields of the coupling products. Electron-rich aryl triflates gave satisfactory results, whereas the electron-poor ones led to the formation of phenols. The Royal Society of Chemistry 2008.
- Roger, Julien,Doucet, Henri
-
p. 169 - 174
(2008/09/20)
-
- Direct arylation of thiophenes via palladium-catalysed C-H functionalisation at low catalyst loadings
-
Palladium associated with cis,cis,cis-1,2,3,4- tetrakis(diphenylphosphinomethyl)cyclopentane (Tedicyp) was found to promote the direct 2-arylation of a variety of thiophene derivatives via C-H functionalisation in good yields using very low catalyst loadings. Electron-deficient, electron-excessive or sterically-congested aryl bromides are tolerated. Moreover, several substituents on the aryl bromide or thiophene derivatives such as acetyl, formyl, nitrile, nitro, ester, methoxy, fluoro or trifluoromethyl are tolerated. The most reactive aryl bromides were coupled with thiophenes derivatives using as little as 0.1-0.01 mol% catalyst.
- Battace, Ahmed,Lemhadri, Mhamed,Zair, Touriya,Doucet, Henri,Santelli, Maurice
-
p. 2507 - 2516
(2008/09/19)
-
- Photoinduced substitution reaction in halothiophenes. Quantum-mechanical and photochemical studies on nitro- and cyano-derivatives
-
2-Iodo-5-nitrothiophene, 2,-bromo-5-cyanothiophene, 2-iodo-5-cyanothiophene, and 4-iodo nitrobenzene were studied by steady state and pulsed methods and by semi-empirical quantum-mechanical computations. The quantum yields for the direct and sensitized photoarylation of these haloromatics following the photocleavage of the carbon-halogen bond were measured in benzene. The transient species originated by direct and sensitized laser excitation were examined by nanosecond laser flash photolysis in benzene and methylcyclohexane. The transients were characterized in terms of absorption spectra and decay lifetimes, and the triplet states were also characterized by phosphorescence measurements in rigid matrices at low temperature. The quenching rate constants of the triplet states and the quantum yields for singlet oxygen production were determined in methylcyclohexane. Findings obtained with sensitizers of various triplet energy showed that an upper triplet state is involved in the photocleaveage of the carbon-halogen bond.
- Aloisi,D'Auria,Latterini,Elisei
-
p. 2765 - 2770
(2007/10/03)
-
- Extension of the Heck reaction to the arylation of activated thiophenes
-
The direct arylation of activated thiophenes was accomplished in moderate to good yields using a Heck-type reaction with the mixture of Pd(OAc)2 and n-Bu4NBr as a catalytic system. This new arylation method is applied to different derivatives and has proved to be compatible with sensitive functional groups. Furthermore, the substituent nature and position on the thiophene moiety influence the cross coupling. In particular the substitution is regiospecific when the heterocycle is substituted at position 2 with an electron withdrawing group.
- Lavenot,Gozzi,Ilg,Orlova,Penalva,Lemaire
-
-