623-20-1Relevant articles and documents
Asymmetric synthesis of piperidines using the nitro-Mannich reaction☆
Anderson, James C.,Bouvier-Israel, Eva,Rundell, Christopher D.,Zhang, Xiangyu
, (2020/12/21)
A method for the synthesis of functionalized piperidines containing 3 contiguous stereocentres in the 2-,3- and 4- positions uses a diastereoselective nitro-Mannich to control stereochemistry. The nitro-Mannich reaction between a β-aryl/heteroaryl substituted nitroalkanes and glyoxylate imine provides β-nitro-amines with good selectivity (70:30 to >95:5) for the syn, anti-diastereoisomers. Reductive cyclisation with BF3.OEt2 and Et3SiH gave, after purification, stereochemically pure piperidines in 19–57% yield for ten examples with different 4-aryl/heteroaryl substituents.
Palladium-Catalyzed Allyl-Allyl Reductive Coupling of Allylamines or Allylic Alcohols with H2as Sole Reductant
Zhou, Xibing,Zhang, Guoying,Huang, Renbin,Huang, Hanmin
supporting information, p. 365 - 369 (2021/01/26)
Catalytic carbon-carbon bond formation building on reductive coupling is a powerful method for the preparation of organic compounds. The identification of environmentally benign reductants is key for establishing an efficient reductive coupling reaction. Herein an efficient strategy enabling H2 as the sole reductant for the palladium-catalyzed allyl-allyl reductive coupling reaction is described. A wide range of allylamines and allylic alcohols as well as allylic ethers proceed smoothly to deliver the C-C coupling products under 1 atm of H2. Kinetic studies suggested that the dinuclear palladium species was involved in the catalytic cycle.
Intramolecular Sakurai Allylation of Geminal Bis(silyl) Enamide with Indolenine. A Diastereoselective Cyclization to Form Functionalized Hexahydropyrido[3,4- b]Indole
Chen, Yi,Gao, Lu,Song, Xuanyi,Song, Zhenlei
supporting information, p. 124 - 128 (2021/01/13)
A fluoride-promoted intramolecular Sakurai allylation of geminal bis(silyl) enamide with indolenine has been developed. The reaction facilitates an efficient cyclization to give hexahydropyrido[3,4-b]indoles in good yields with high diastereoselectivity. The resulted cis, trans-stereochemistry further enables the ring-closing metathesis (RCM) reaction of two alkene moieties, giving a tetracyclic N-hetereocycle widely found as the core structure in akuammiline alkaloids.
Process for the preparation of fatty acids
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Paragraph 0156-0159, (2020/09/04)
The invention discloses a method for preparing fatty acid. The method comprises the following steps: providing a first reactant which is a furan compound containing an carbonyl group; providing a second reactant which is a compound containing a carboxyl group, an ester group or an anhydride group and can participate in a condensation reaction with the carbonyl group of the first reactant; allowingthe first reactant and the second reactant to participate in a first condensation reaction, and allowing a C=O bond of the carbonyl group of the first reactant to be connected with alpha carbon of the carbonyl group of the second reactant and to be converted into a C=C bond so as to form a condensation product; and carrying out a second-step reaction under hydrogen pressure in the presence of a co-catalytic system of a hydrogenation catalyst and Lewis acid, opening a furan ring of the condensation product, carrying out hydrodeoxygenation at the same time, removing all oxygen except for oxygenin the carboxyl group, and allowing a carbon chain to be saturated so as to obtain the fatty acid.
CYCLOBUTANE-1, 3-DIACID BUILDING BLOCKS
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Paragraph 0048; 0115; 0127; 0129, (2019/01/16)
A method of making polymers utilizes cyclobutane-1,3-diacid (CBDA) molecules as polymer building blocks includes and linker molecules with a non-reactive R group and at least two reactive X groups used to create chemically stable polymers of CBDA. The resulting polymers are thermally, photochemically, and chemically stable.
A computational triage approach to the synthesis of novel difluorocyclopentenes and fluorinated cycloheptadienes using thermal rearrangements
Orr, David,Percy, Jonathan M.,Harrison, Zo? A.
, p. 6369 - 6380 (2016/10/03)
Electronic structure calculations have been used for the effective triage of substituent effects on difluorinated vinylcyclopropane precursors and their ability to undergo vinyl cyclopropane rearrangements (VCPR). Groups which effectively stabilised radicals, specifically heteroarenes, were found to result in the lowest energy barriers. Ten novel precursors were synthesised to test the accuracy of computational predictions; the most reactive species which contained heteroarenes underwent thermal rearrangements at room temperature to afford novel difluorocyclopentenes and fluorinated benzocycloheptadienes through competing VCPR and [3,3]-rearrangement pathways, respectively. More controlled rearrangement of ethyl 3-(1′(2′2′-difluoro-3′-benzo[d][1,3]dioxol-5-yl)cyclopropyl)propenoate (22) allowed these competing pathways to be monitored at the same time and activation energies for both reactions were determined; Ea(VCPR) = (23.4 ± 0.2) kcal mol-1 and Ea([3,3]) = (24.9 ± 0.3) kcal mol-1. Comparing our calculated activation energies with these parameters showed that no single method stood out as the most accurate for predicting barrier heights; (U)M05-2X/6-31+G? methodology remained the best for VCPR but M06-2X/6-31G? was better for the [3,3]-rearrangement. The consistency observed with (U)B3LYP/6-31G? calculations meant that it came closest to a universal method for dealing with these systems. The developed computational design model correctly predicted the observed selectivity of rearrangement pathways for both our system and literature compounds.
Single-site palladium(II) catalyst for oxidative heck reaction: Catalytic performance and kinetic investigations
Duan, Hui,Li, Menghuan,Zhang, Guanghui,Gallagher, James R.,Huang, Zhiliang,Sun, Yu,Luo, Zhong,Chen, Hongzhong,Miller, Jeffrey T.,Zou, Ruqiang,Lei, Aiwen,Zhao, Yanli
, p. 3752 - 3759 (2015/06/16)
The development of organometallic single-site catalysts (SSCs) has inspired the designs of new heterogeneous catalysts with high efficiency. Nevertheless, the application of SSCs in certain modern organic reactions, such as C-C bond formation reactions, has still been less investigated. In this study, a single-site Pd(II) catalyst was developed, where 2,2′-bipyridine-grafted periodic mesoporous organosilica (PMO) was employed as the support of a Pd(II) complex. The overall performance of the single-site Pd(II) catalyst in the oxidative Heck reaction was then investigated. The investigation results show that the catalyst displays over 99% selectivity for the product formation with high reaction yield. Kinetic profiles further confirm its high catalytic efficiency, showing that the rate constant is nearly 40 times higher than that for the free Pd(II) salt. X-ray absorption spectroscopy reveals that the catalyst has remarkable lifetime and recyclability.
Unusual temperature dependence of salt effects for "on water" Wittig reaction: Hydrophobicity at the interface
Tiwari, Shraeddha,Kumar, Anil
scheme or table, p. 4445 - 4447 (2009/05/06)
An unusual variation with temperature of the salt effects in aqueous Wittig reaction is observed, suggesting that hydrophobic acceleration of reactions comprising "on water" reactants is fundamentally different from that for reactions with small non-polar solutes. The Royal Society of Chemistry.
One-pot Wittig reactions in water and in the presence of a surfactant
Orsini, Fulvia,Sello, Guido,Fumagalli, Tiziano
, p. 1717 - 1718 (2008/02/03)
α,β-Unsaturated esters were synthesized in open atmosphere via mild and efficient one-pot Wittig reactions performed in both water and sodium dodecyl sulfate (SDS)-water solution. Georg Thieme Verlag Stuttgart.
New solid-supported phosphonate reagents for the synthesis of Z-α,β-unsaturated esters
Martina, Sébastien L. X.,Taylor, Richard J. K.
, p. 3279 - 3282 (2007/10/03)
Novel solid-supported phosphonate reagents have been prepared and evaluated for the synthesis of α,β-unsaturated esters with a preference for the Z-alkene. The optimal reagent was a hybrid of both Still-Gennari and Ando reagents, and showed good to high yields and fair to good Z-selectivity for the conversion of both aliphatic and aromatic aldehydes.
