23343-06-8Relevant articles and documents
Hydride transfer reactions of 5-(2-alkohybenzylidene) barbituric acids: Synthesis of 2,4,6-trioxoperhydropyrimidine-5-spiro-3′-chromanes
Krasnov, Konstantin A.,Dorovatovskii, Pavel V.,Zubavichus, Yan V.,Timofeeva, Tatiana V.,Khrustalev, Victor N.
, p. 542 - 549 (2017/01/12)
The thermal cyclization of 5-(2-phenoxymethylphenyl-methylene)barbituric acid and its derivatives affords 2,4,6-trioxoperhydropyrimidine-5-spiro-3′-chromanes. The reactions require no catalysts and proceed at temperatures from 118 to 240?°C depending on the substrate activity. These cyclization reactions are analogous to T-reactions of tertiary amines involving the hydride transfer.
Cycloisomerization between Aryl Enol Ether and Silylalkynes under Ruthenium Hydride Catalysis: Synthesis of 2,3-Disubstituted Benzofurans
Ohno, Shohei,Takamoto, Kohei,Fujioka, Hiromichi,Arisawa, Mitsuhiro
supporting information, p. 2422 - 2425 (2017/05/12)
Metal-catalyzed cycloisomerization reactions of 1,n-enynes have become conceptually and chemically attractive processes in the search for atom economy, which is a key subject of current research. However, metal-catalyzed cycloisomerization between aryl enol ether and silylalkynes has not been developed. The ruthenium hydride complex catalyzed cycloisomerization between aryl enol ether and silylalkynes is reported to give benzofurans having useful functional groups, vinyl and trimethylsilylmethyl, on the 2- and 3-positions, respectively.
A cascade Claisen rearrangement/o-quinone methide formation/electrocyclization approach to 2H-chromenes
Song, Liyan,Huang, Fang,Guo, Liwen,Ouyang, Ming-An,Tong, Rongbiao
supporting information, p. 6021 - 6024 (2017/07/10)
A new approach has been developed for the synthesis of 8-substituted 2H-chromenes, featuring a novel cascade aromatic Claisen rearrangement/o-quinone methide formation/6π-electrocyclization. This new method was demonstrated with 28 examples tolerating different substitutions at alkenes, allylic and aromatic ring and with total syntheses of three 2H-chromene natural products.
Synthesis of Allyl- and Prenylcoumarins via Microwave-Promoted Tandem Claisen Rearrangement/Wittig Olefination
Schmidt, Bernd,Riemer, Martin
supporting information, p. 141 - 149 (2015/12/26)
Allyl, dimethylallyl, crotyl, and prenyl ethers of various aromatic ortho-hydroxy carbonyl compounds undergo a tandem sequence of Claisen rearrangement, carbonyl olefination, and cyclization upon microwave irradiation in the presence of a stabilized ylide. The products are multiply substituted 6- or 8-allylated or prenylated coumarins (2H-chromen-2-ones).
The Synthesis of 5-Amino-dihydrobenzo[b]oxepines and 5-Amino-dihydrobenzo[b]azepines via Ichikawa Rearrangement and Ring-Closing Metathesis
Chwastek, Monika,Pieczykolan, Micha?,Stecko, Sebastian
, p. 9046 - 9074 (2016/10/17)
The combination of Ichikawa's rearrangement and a ring-closing metathesis reaction of allyl carbamates is presented as a method for the preparation of 5-amino-substituted 2,5-dihydro-benzo[b]oxepines, 2,5-dihydro-benzo[b]azepines, and 2,5-dihydro-benzo[b]thiepins. It was demonstrated that the use of nonracemic allyl carbamates enables the synthesis of enantioenriched benzo-fused seven-membered heterocycles. Finally, it was shown that further functionalization of the obtained structures allows access to pharmacologically active 5-amino-substituted 2,3,4,5-tetrahydro-1-benzo[b]oxepine scaffolds.
Silaborative Carbocyclizations of 1,7-Enynes. Diastereoselective Preparation of Chromane Derivatives
Xiao, You-Cai,Moberg, Christina
supporting information, p. 308 - 311 (2016/02/03)
Palladium(0)-catalyzed carbocyclization of 1,7-enynes mediated by (chlorodimethylsilyl)pinacolborane proceeds with 1,8-addition of the silicon and boron functions to give functionalized cyclohexane derivatives with boron attached to the exocyclic olefin. A variety of chromane dervatives are accessible by this method. In contrast to the analogous reactions with 1,6-enynes, the configuration of the newly formed stereogenic center is controlled by a stereogenic center present in the substrate.
Alternating Ring-Opening Copolymerization of Cyclohexene Oxide and Maleic Anhydride with Diallyl-Modified Manganese(III)-Salen Catalysts
Liu, Dengfeng,Zhang, Zhao,Zhang, Xingmei,Lü, Xingqiang
, p. 47 - 55 (2016/01/26)
A series of diallyl-modified (salen)MnIII complexes have been designed, synthesized, and applied in the cyclohexene oxide and maleic anhydride ring-opening copolymerization. The experimental results show that these complexes are effective in the presence of co-catalyst 4-(dimethylamino)pyridine (DMAP). Of all the five catalysts, the catalyst (salcyen)MnCl (salcyen=2-((E)-(2-((E)-5-allyl-2-hydroxy-3-methoxybenzylideneamino)cyclohexylimino)methyl)-4-allyl-6-methoxyphenol) exhibited the best catalytic performance under the conditions applied, and the cyclohexane of diimine bridge is conjugated with the two diallyl-salen-type moieties. This conjugation can increase the electron density of the centre MnIII cation so that catalyst (salcyen)MnCl favours the formation of reaction intermediates. Moreover, the anion effect of Cl- is proved to be the best in the catalytic performances. Among the three co-catalysts (DMAP, triphenylphosphine (Ph3P), and tetra-n-butylammonium bromide (n-Bu4NBr)) tested, DMAP is the most efficient towards monomer conversion and polymer chain growth.
Organoselenium and DMAP co-catalysis: Regioselective synthesis of medium-sized halolactones and bromooxepanes from unactivated alkenes
Verma, Ajay,Jana, Sadhan,Prasad, Ch. Durga,Yadav, Abhimanyu,Kumar, Sangit
supporting information, p. 4179 - 4182 (2016/03/19)
A catalytic system consisting of bis(4-methoxyphenyl)selenide and 4-(dimethylamino)pyridine (DMAP) has been developed for the regioselective synthesis of medium-sized bromo/iodo lactones and bromooxepanes possessing high transannular strain. 77Se NMR, mass spectrometry and theoretical studies reveal that the reaction proceeds via a quaternary selenium intermediate.
The first example of Tb3-containing metallopolymer-type hybrid materials with efficient and high color-purity green luminescence
Zhang, Zhao,Feng, Heini,Liu, Lin,Yu, Chao,Lü, Xingqiang,Zhu, Xunjin,Wong, Wai-Kwok,Jones, Richard A.,Pan, Mei,Su, Chengyong
, p. 6229 - 6241 (2015/03/30)
In the series of homo-leptic trinuclear complexes {[Ln3(L)4Cl4(MeOH)(H2O)]·Cl} (Ln = La, 1; Ln = Eu, 2; Ln = Tb, 3 or Ln = Gd, 4) self-assembled from the allyl-modified benzimidazole-type ligand HL (4-allyl-2-(1H-benzo[d]imidazol-2-yl)-6-methoxyphenol) and LnCl3·6H2O, a suitable energy level match endows efficient green luminescence (Φoverall = 72%) of Tb3-arrayed complex 3. The copolymerization between each of these complex monomers 1-4 and CC-containing MMA (methyl methacrylate) or NBE (norbornene) shows that degradative chain transfer of the terminal four flexible allyl groups within restrains their radical polymerization with MMA while it does not hinder their effective ring-opening metathesis polymerization (ROMP) with NBE. Thus, two kinds of PMMA-supported doping hybrid materials 1@PMMA, 2@PMMA, 3@PMMA and 4@PMMA and PNBE-supported metallopolymer-type hybrid materials Poly(NBE-1), Poly(NBE-2), Poly(NBE-3) and Poly(NBE-4) are obtained, respectively. Especially for both 3@PMMA and Poly(NBE-3) with high color-purity characteristic green emission of Tb3+ ions, improved physical properties including significantly enhanced luminescence (Φoverall = 76% or 83%) are observed, and covalent-bonding endows a higher-concentration self-quenching as compared to physical doping. This journal is
Dienamine and friedel-crafts one-pot synthesis, and antitumor evaluation of diheteroarylalkanals
Frías, María,Padrón, José M.,Alemán, José
supporting information, p. 8237 - 8241 (2015/05/27)
An asymmetric synthesis of diheteroarylalkanals through one-pot dienamine and Friedel-Crafts reaction is presented. The reaction tolerates a large variety of substituents at different positions of the starting aldehyde and also in the indole nucleophile, and a range of diheterocyclic alkanals can be achieved. Furthermore, we have studied the antiproliferative activity of these new compounds in representative cancer tumor cell lines. All in one: An asymmetric synthesis of diheteroarylalkanals through a one-pot dienamine and Friedel-Crafts reaction is presented (see scheme). The reaction tolerates a large variety of substituents at different positions of the starting aldehyde, and the use of nucleophiles and different diheterocyclic alkanals can also be achieved. The antiproliferative activity of these new compounds in different cancer tumor cell lines has also been investigated and it was found that, with the appropriate substitution, the compounds are as cytotoxic as Cisplatin.