- Catalytic Asymmetric Allylic Substitution with Copper(I) Homoenolates Generated from Cyclopropanols
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By using copper(I) homoenolates as nucleophiles, which are generated through the ring-opening of 1-substituted cyclopropane-1-ols, a catalytic asymmetric allylic substitution with allyl phosphates is achieved in high to excellent yields with high enantioselectivity. Both 1-substituted cyclopropane-1-ols and allylic phosphates enjoy broad substrate scopes. Remarkably, various functional groups, such as ether, ester, tosylate, imide, alcohol, nitro, and carbamate are well tolerated. Moreover, the present method is nicely extended to the asymmetric construction of quaternary carbon centers. Some control experiments argue against a radical-based reaction mechanism and a catalytic cycle based on a two-electron process is proposed. Finally, the synthetic utilities of the product are showcased by means of the transformations of the terminal olefin group and the ketone group.
- Shi, Chang-Yun,Yin, Liang,Zhang, Qi,Zhou, Si-Wei
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supporting information
p. 26351 - 26356
(2021/11/09)
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- Development of a novel secondary phosphine oxide-ruthenium(II) catalyst and its application for carbonyl reduction
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A secondary phosphine oxide-phosphine mixed tridentate ligand and its ruthenium complex have been developed. This complex shows excellent catalytic activity for carbonyl reduction, especially for the reduction of α,β-unsaturated aldehydes. The turnover number and selectivity can reach up to 36500 and 99%, respectively. Control experiments and DFT calculations supported an outer-sphere mechanism during the hydrogenation reaction.
- Tan, Xuefeng,Zeng, Weijun,Zhang, Xiaoyong,Chung, Lung Wa,Zhang, Xumu
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supporting information
p. 535 - 538
(2018/01/19)
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- Tridentate phosphine ligand, catalyst and preparation method and application thereof
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The invention belongs to the field of asymmetric catalysis, and discloses tridentate phosphine ligand which is of a structure of formula I as shown in the specification, wherein R is aryl or substituted aryl. The invention further discloses a catalyst prepared from the ligand. The catalyst is of a structure of formula II as shown in the specification, wherein R is aryl or substituted aryl, and L is mono-phosphine ligand. The invention further discloses application of the catalyst in a catalytic reduction reaction. The invention provides a tridentate phosphine ligand which is novel in structure, and a ruthenium complex of the tridentate phosphine ligand. carbonyl compounds, namely aldehyde and ketone, particularly alpha,beta-unsaturated aldehyde, are reduced by using the ruthenium complex, and very good reaction activity and selectivity are achieved.
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Paragraph 0055-0057
(2017/12/30)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- THERMAL ELECTROCYCLIC RING-OPENING OF CYCLOBUTENES: STEREOSELECTIVE ROUTES TO FUNCTIONALISED CONJUGATED (Z,E)- AND (E,E)-2,4-DIENALS
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The cyclobutenecarbaldehyde 12 undergoes thermal electrocyclic ring-opening at low temperature, producing the (2Z,4E)-hexadienal 13 exclusively.By contrast, unsymmetrical derivatives of cis-3-cyclobutene-1,2-dicarboxylic acid undergo ring-opening at 80-110 deg C with low levels of stereoselectivity, which vary according to the balance of the electronic and, to a lesser extent, the steric nature of the substituents located on the rehybridising carbon atoms.
- Binns, Falmai,Hayes, Roy,Ingham, Stephen,Saengchantara, Suthiweth T.,Turner, Ralph W.,et al
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p. 515 - 530
(2007/10/02)
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- SYNTHESIS OF SORBIC ALCOHOL (2E,4E-HEXADIEN-1-OL)
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The decomposition of 1-acetoxy-3-acetoxymethoxy-4-hexene by the action of acids leads to a 1:2 mixture of 1-acetoxy-2,4-hexadiene and 1-acetoxy-3,5-hexadiene.The same compounds are formed in a ratio of 1:1 during the pyrolysis of 1,3-diacetoxy-4-hexene.
- Vasil'ev, A. A.,Poddubnaya, S. S.,Cherkaev, G. V.,Cherkaev, V. G.
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p. 1457 - 1460
(2007/10/02)
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- An Approach to Cytochalasan Synthesis: Macrolide Formation by an Intramolecular Diels-Alder Reaction. X-Ray Structure of Methyl (1RS, 2SR, 5RS, 6RS)-2,5-Dimethyl-1-hydroxy-6-cyclohex-3-ene-1-carboxylate
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When heated in toluene under reflux, under high dilution conditions, trans,trans-hexadeca-12,14-dienoyl-oxymaleic anhydride (4) cyclised via an intramolecular Diels-Alder reaction to give the macrocyclic lactone (5) in 27percent yield together with 5percent of a regioisomer (23). (1RS, 2SR, 5RS, 6RS)-2,5-Dimethyl-1-octanoyloxycyclohex-3-ene-1,6-dicarboxylic acid anhydride (11) was converted into the methyl (1RS, 2SR, 5RS, 6RS)-2,5-dimethyl-1-octanoyloxy-6-benzylcarbonylcyclohex-3-ene-1-carboxylate (33), but selective reduction of this ketone was unsuccessful.The structure of one of the reduction products, methyl (1RS, 2SR, 5RS, 6RS)-2,5-dimethyl-1-hydroxy-6-cyclohex-3-ene-1-carboxylate (35) was confirmed by an X-ray structure determination.
- Bailey, Stephen J.,Thomas, Eric J.,Vather, Sunil M.,Wallis, John
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p. 851 - 860
(2007/10/02)
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- Novel Synthesis of (Z)-3-Hexen-1-ol and cis-Jasmone
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Both (Z)-3-hexen-1-ol and cis-jasmone were synthesised via 1,4-selective hydrogenation of conjugated dienes in the presence of arene Cr(CO)3 or Cr(CO)6 catalysts as the key step.
- Furuhata, Akimichi,Onishi, Ken,Fujita, Akira,Kogami, Kunio
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p. 1757 - 1760
(2007/10/02)
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