- Palladium-Titanium Relay Catalysis Enables Switch from Alkoxide-π-Allyl to Dienolate Reactivity for Spiro-Heterocycle Synthesis
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Reported herein is the divergent syntheses of [5,5] and [6,5] spiro-heterocycles under Lewis-acid-assisted palladium catalysis. In particular, an unprecedented switch from alkoxide-π-allyl to dienolate reactivity was achieved by the use of palladium-titanium relay catalysis, and represents umpolung reactivity of vinylethylene carbonates. This method uses a simple procedure and commercially available catalysts, and delivers both classes of spiro-heterocycles, bearing three contiguous stereocenters, in high yield and uniformly excellent diastereoselectivity.
- Yang, Li-Cheng,Tan, Zher Yin,Rong, Zi-Qiang,Liu, Ruoyang,Wang, Ya-Nong,Zhao, Yu
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- A Domino Process toward Functionally Dense Quaternary Carbons through Pd-Catalyzed Decarboxylative C(sp3)-C(sp3) Bond Formation
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An efficient protocol was developed to construct functionally dense quaternary carbons with concomitant formation of a new Csp3-Csp3 bond via Pd-catalyzed decarboxylative transformation of vinyl cyclic carbonates. This redox-neutral catalytic system features stereocontrolled formation of multisubstituted allylic scaffolds with an aldehyde functionality generated in situ, and it typically can be performed at room temperature without any additives. DFT calculations provide a rationale toward the selective formation of these compounds and reveal a complex mechanism that with the help of microkinetic models is able to reproduce the nontrivial dependence of the identity of the product on the nature of the substituents in the substrate.
- Guo, Wusheng,Kuniyil, Rositha,Gómez, José Enrique,Maseras, Feliu,Kleij, Arjan W.
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- Pd-Catalyzed Umpolung of π-Allylpalladium Intermediates: Assembly of All-Carbon α-Vinyl Quaternary Aldehydes through C(sp3)-C(sp3) Coupling
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Construction of sterically congested all-carbon quaternary centers represents a formidable challenge in synthetic chemistry. The method described herein provides direct and facile access to a series of structurally diverse and synthetically useful aliphatic aldehydes, bearing an all-carbon α-vinyl quaternary center and a 1,5-diene functionality, through Pd-catalyzed umpolung of vinylethylene carbonates (VECs). The reaction features electrophilic-to-nucleophilic reactivity reversal of the VEC-derived π-allyl-palladium intermediate via an unusual β-hydride elimination process, and the resultant enolate is chemoselectively coupled with allylic acetate to form an α-vinyl aldehyde embedded with an all-carbon quaternary center.
- Wang, Huifei,Qiu, Shuxian,Wang, Sasa,Zhai, Hongbin
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- Asymmetric Catalytic Vinylogous Addition Reactions Initiated by Meinwald Rearrangement of Vinyl Epoxides
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The first catalytic asymmetric multiple vinylogous addition reactions initiated by Meinwald rearrangement of vinyl epoxides were realized by employing chiral N,N′-dioxide/ScIII complex catalysts. The vinyl epoxides, as masked β,γ-unsaturated aldehydes, via direct vinylogous additions with isatins, 2-alkenoylpyridines or methyleneindolinones, provided a facile and efficient way for the synthesis of chiral 3-hydroxy-3-substituted oxindoles, α,β-unsaturated aldehydes and spiro-cyclohexene indolinones, respectively with high efficiency and stereoselectivity. The control experiments and kinetic studies revealed that the Lewis acid acted as dual-tasking catalyst, controlling the initial rearrangement to match subsequent enantioselective vinylogous addition reactions. A catalytic cycle with a possible transition model was proposed to illustrate the reaction mechanism.
- Dong, Shunxi,Feng, Xiaoming,He, Jun,Lin, Lili,Song, Yanji,Xu, Jinxiu
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supporting information
p. 14521 - 14527
(2021/05/21)
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- Rhodium-Catalyzed Regioselective Hydroformylation of Alkynes to α,β-Unsaturated Aldehydes Using Formic Acid
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A rhodium-catalyzed hydroformylation of alkynes with formic acid was developed. The method provides α,β-unsaturated aldehydes in high yield and E-selectivity without the need to handle toxic CO gas.
- Fan, Chao,Hou, Jing,Chen, Yu-Jia,Ding, Kui-Ling,Zhou, Qi-Lin
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supporting information
p. 2074 - 2077
(2021/04/05)
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- Binuclear Pd(I)-Pd(I) Catalysis Assisted by Iodide Ligands for Selective Hydroformylation of Alkenes and Alkynes
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Since its discovery in 1938, hydroformylation has been thoroughly investigated and broadly applied in industry (>107 metric ton yearly). However, the ability to precisely control its regioselectivity with well-established Rh- or Co-catalysts has thus far proven elusive, thereby limiting access to many synthetically valuable aldehydes. Pd-catalysts represent an appealing alternative, yet their use remains sparse due to undesired side-processes. Here, we report a highly selective and exceptionally active catalyst system that is driven by a novel activation strategy and features a unique Pd(I)-Pd(I) mechanism, involving an iodide-assisted binuclear step to release the product. This method enables β-selective hydroformylation of a large range of alkenes and alkynes, including sensitive starting materials. Its utility is demonstrated in the synthesis of antiobesity drug Rimonabant and anti-HIV agent PNU-32945. In a broader context, the new mechanistic understanding enables the development of other carbonylation reactions of high importance to chemical industry.
- Zhang, Yang,Torker, Sebastian,Sigrist, Michel,Bregovi?, Nikola,Dydio, Pawe?
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supporting information
p. 18251 - 18265
(2020/11/02)
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- Synthetic Strategy for Tetraphenyl-Substituted All-E-Carotenoids with Improved Molecular Properties
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The synthetic method of tetraphenyl-substituted all-E-carotenes 1 with improved properties of antioxidant and molecular electronic conductance was developed through the formation of tetraphenyl-substituted all-E-apocarotenedial 4. The synthesis highlighted the preparation of novel subunits containing phenyl substituent(s) with E-configuration starting from the key (E)-4-chloro-2-phenylbut-2-enal (10), utilizing conjugation effect with formyl group or easy recrystallization of sulfone compounds. Sulfone-mediated coupling methods of Julia and modified Julia–Kocienski olefinations utilizing the subunits were demonstrated to produce tetraphenyl-substituted apocarotenedials 4. The major all-E-forms (73–85 % selectivity) were easily purified by SiO2 chromatography and trituration with Et2O due to the presence of the polar formyl groups. The olefination of all-E-apocarotenedials 4 and Wittig salt 5 provided all-E-9,9',13,13'-tetraphenylcarotenes 1.
- Chung, Wook-Jin,Jung, Hyunuk,Koo, Sangho,Lim, Boram,Park, Myeongnam,Yang, Huijeong,Yoo, Hyebin
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- Vinylethylene Carbonates as α,β-Unsaturated Aldehyde Surrogates for Regioselective [3 + 3] Cycloaddition
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Herein, we report a novel stepwise addition-controlled ring size method, to access tetrahydropyrimidines through an operationally simple [3 + 3] cycloaddition of vinylethylene carbonates with triazinanes. Interestingly, we could also use this method for a [3 + 3] oxidative cycloaddition, which allows the facile synthesis of polysubstituted terphenyls under mild conditions. Mechanistic studies suggest that vinylethylene carbonates could generate α,β-unsaturated aldehydes as 3-carbon synthons for cycloaddition via a combination process of Pd-catalyzed decarboxylation and β-H elimination.
- Xu, Yi,Chen, Lu,Yang, Yu-Wen,Zhang, Zhiqiang,Yang, Weibo
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p. 6674 - 6678
(2019/09/03)
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- Ligand-controlled regiodivergent π-allyl palladium catalysis enables a switch between [3+2] and [3+3] cycloadditions
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Reported herein is the use of ligands to tune the regioselectivity and reactivity of palladium-catalyzed [3+2] and [3+3] cycloadditions. Diverse synthesis with vinylethylene carbonates (VECs) as well as free naphthols has been explored to construct four different valuable polycyclic frameworks in a broad substrate scope.
- Xia, Yu,Bao, Qiao-Fei,Li, Yuke,Wang, Li-Jing,Zhang, Bo-Sheng,Liu, Hong-Chao,Liang, Yong-Min
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supporting information
p. 4675 - 4678
(2019/05/02)
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- 2,7-DIPHENYLOCTA-2,4,6-TRIENEDIAL, METHOD FOR PREPARING THE SAME AND METHOD FOR PREPARING CAROTENOIDS CONTAINING PHENYL SUBSTITUENTS USING THE SAME
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The present invention relates to an intermediate, a method for synthesizing the same, and a method for efficiently synthesizing a carotene compound containing a phenyl substituent using the same, wherein the intermediate needed to prepare a polyene structure of a carotene compound having a variety of physicochemical and electroelectronic properties according to electronic properties of the phenyl substituent in a single step reaction, and exhibiting improved antioxidant abilities by containing the phenyl substituent. To this end, 2,7-diphenyl-2,4,6-trienedial of chemical formula 1, which is a novel compound, and 2-((3-(5,5-dimethyl-1,3-dioxane-2-yl)-3-phenylallyl)sulfonyl)benzo[d]thiazole of chemical formula 2, and a synthesis method thereof are proposed by an efficient method using a common intermediate. The novel compound can be efficiently used for synthesis of a carotene compound containing various phenyl substituents through a Julia-Kocienski reaction or a Wittig reaction.COPYRIGHT KIPO 2019
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Paragraph 0130-0133
(2019/02/27)
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- Mixtures having improved cooling effect
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A mixtures which contain (a) at least one phenylalkenal of formula (I) wherein R1 and R2 independently represent hydrogen, a methyl or phenyl group, R3 represents hydrogen, a phenyl group, alkenyl group or a linear or branched alkyl group with 1 to 5 carbon atoms, and the broken double lines independently represent a single bond or a double bond, and (b) at least one physiological cooling agent.
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Page/Page column 28
(2017/09/15)
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- Selective rhodium-catalyzed hydroformylation of alkynes to α,β-unsaturated aldehydes with a tetraphosphoramidite ligand
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A tetraphosphoramidite ligand was successfully applied to a Rh-catalyzed hydroformylation of various symmetrical and unsymmetrical alkynes to afford corresponding α,β-unsaturated aldehyde products in good to excellent yields (up to 97% yield). Excellent chemo- and regioselectivities and high activities (up to 20 000 TON) were achieved. The corresponding α,β-unsaturated aldehyde products can be transformed into many useful and important organic molecules, such as indenamine derivatives and lukianol pyrroles. This great performance makes the hydroformylation of alkynes highly practical with great potential.
- Zhang, Zongpeng,Wang, Qian,Chen, Caiyou,Han, Zhengyu,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 3290 - 3293
(2016/07/13)
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- Selective palladium-catalyzed hydroformylation of alkynes to α,β-Unsaturated Aldehydes
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Atom-efficient: A selective palladium catalyst system is used for the hydroformylation of alkynes (see picture). In this syngas reaction, various alkynes were smoothly transformed to synthetically interesting α,β-unsaturated aldehydes in good yields with high regio- and stereoselectivity. Copyright
- Fang, Xianjie,Zhang, Min,Jackstell, Ralf,Beller, Matthias
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p. 4645 - 4649
(2013/05/22)
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- Palladium-catalysed Heck reaction on 1,2-dien-1-ols: a stereoselective synthesis of α-arylated α,β-unsaturated aldehydes
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A new methodology for preparing α-arylated α,β-unsaturated aldehydes is reported. The starting materials are all commercially available alkyn-1-ols (1a-c) that have been easily isomerised to the corresponding allenes (2a-c). The key step is the Heck coupling of the 1,2-dien-1-ols with a series of iodo- and bromoarene. The products have been synthesised in good yields, and the reactions were carried out under very mild conditions.
- Deagostino, Annamaria,Prandi, Cristina,Toppino, Antonio,Venturello, Paolo
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p. 10344 - 10349
(2008/12/22)
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- Lewis acid-catalyzed tandem Diels-Alder reaction/retro-Claisen rearrangement as an equivalent of the inverse electron demand hetero Diels-Alder reaction
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A highly stereoselective formal inverse electron demand hetero Diels-Alder reaction (HDA) occurs on reaction of 2-aryl-α,β-unsaturated aldehydes with cyclopentadiene. The major pathway for this transformation is shown to be a Lewis acid-catalyzed tandem Diels-Alder reaction/retro-Claisen rearrangement.
- Davies, Huw M. L.,Dai, Xing
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p. 6680 - 6684
(2007/10/03)
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- Phosphine Catalyzed α-Arylation of Enones and Enals Using Hypervalent Bismuth Reagents: Regiospecific Enolate Arylation via Nucleophilic Catalysis
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Exposure of enones and enals to 20 mol % tributylphosphine in the presence of triarylbismuth(V) dichlorides results in regiospecific aryl transfer to the α-position of the enone or enal pronucleophile. These results represent the first examples of enolate
- Koech, Phillip K.,Krische, Michael J.
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p. 5350 - 5351
(2007/10/03)
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- Rhodium-katalysierte Hydroformylierung innerer Alkine zu α,β-ungesaettigten Aldehyden
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Keywords: Alkine; Hydroformylierungen; Katalyse; Alkene; Rhodiumverbindungen
- Johnson, John R.,Cuny, Gregory D.,Buchwald, Stephen L.
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p. 1877 - 1879
(2007/10/03)
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- Preparation of α,β-unsaturated carbonyl compounds
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A process for the preparation of α,β-unsaturated carbonyl compounds of the formula I STR1 where R1 is hydrogen, C1 -C10 -alkyl, C1 -C10 -alkoxy or aryloxy, R2 is aryl which is unsubstituted or substituted by C1 -C4 -alkyl, C1 -C4 -alkoxy, trifluoromethyl and/or halogen and R3 is tetrahydrofuranyl or aryl which is substituted by C1 -C4 -alkyl, C1 -C4 -alkoxy, trifluoromethyl and/or halogen, which comprises reacting 3-amino-2-propen-1-ones of the formula II STR2 where R1 and R2 have the abovementioned meanings, and R4 and R5 are, independently of one another, hydrogen, C1 -C10 -alkyl or aryl, with a magnesium halide of the formula III where Y is halogen, at from -20° to 100° C., and novel α,β-unsaturated carbonyl compounds and novel 3-amino-2-propen-1-ones are described.
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- SYNTHESIS OF SUBSTITUTED TETRAHYDROPYRIDINES AND M-HYDROXYBENZOIC ACIDS
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A series of substituted 1,2,3,6- (5) and 1,2,5,6-tetrahydropyridines (6) have been synthesised via intramolecular 1,6-Michael addition of methoxycarbonyl-2,4-dienylamines (10).The kinetics of these reactions have been investigated and an explanation of substituent effects is advanced.Also a new route to m-hydroxybenzoic acids has been established by cyclisation of substituted hexa-3,4:5,6-dienoic acids.
- Clinch, K.,Marquez, C. J.,Parrott, M. J.,Ramage, R.
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p. 239 - 258
(2007/10/02)
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- CHEMISTRY OF ENOL ETHERS. LXXVII. SYNTHESIS OF ACETALS OF PHENYLSUBSTITUTED GLUTACONALDEHYDES
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The condensation of the acetals of acetophenone and acetaldehyde with enol ethers, as a result of which 2- and 3-phenyl-1,1,3-trialkoxybutanes were obtained, was studied.The acid hydrolysis of the products leads to the formation of 2- and 3-phenylbutenals, from which 2- and 3-phenyl-1-trimethylsilyloxy-1,3-butadienes were obtained by the action of trimethylchlorosilane and triethylamine.The reaction of the silyloxydienes with ethyl orthoformate in the presence of zinc chloride as catalyst gave the monoacetals of α- and β-phenylglutaconaldehydes, which were converted into the corresponding bisacetals by the further action of the orthoformate.
- Makin, S. M.,Kruglikova, R. I.,Lonina, N. N.
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p. 847 - 852
(2007/10/02)
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- Epoxydes α-ethyleniques et phenate de sodium: acces a des ethers phenoliques et phenols ortho-allyliques
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The ring cleavage reactions of α-ethylenic epoxides by sodium phenoxide afforded a mixture of products.Problems of competitive attack by this nucleophile, at the less substituted carbon (compounds A) or at the β-ethylenic carbon atom (compounds B and C), were encountered and could be resolved by judicious choice of reaction conditions (solvents, stereochemistry of the oxiranes).The regioselectivity of the attack was dependent on the transition states, implying weak steric hindrance and a conjugation oxirane - double bond.
- David, Michele,Sauleau, Jean,Sauleau, Armelle
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p. 2449 - 2454
(2007/10/02)
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- Regio- and Stereoselective Hydrosulfonylation of Conjugated Dienes via a (?-Allyl)palladium Complex
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The combination of a sulfonylpalladation of acyclic dienes 1 (with 2 equiv of NaSO2R and 1 equiv of PdCl2 in acetic acid or acetic acid-H2O at 50-80 deg C under air) and a protiodepalladation of the thus obtained palladium complexes 3 with dimethylglyoxime (in a protic solvent at room temperature) provides di- and trisubstituted (Z)-Δ3-sulfones 12 selectively, irrespective of the stereochemistry of the starting dienes.Similar treatment of 1-vinylcycloalkenes 5 (n (1,3) strain between Pd and the substituent on the allylic position.
- Tamaru, Yoshinao,Yamada, Yoshimi,Kagotani, Masahiro,Ochiai, Hirofumi,Nakajo, Eiji,et al.
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p. 4669 - 4681
(2007/10/02)
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