4411-89-6Relevant academic research and scientific papers
Palladium-Titanium Relay Catalysis Enables Switch from Alkoxide-π-Allyl to Dienolate Reactivity for Spiro-Heterocycle Synthesis
Yang, Li-Cheng,Tan, Zher Yin,Rong, Zi-Qiang,Liu, Ruoyang,Wang, Ya-Nong,Zhao, Yu
, p. 7860 - 7864 (2018)
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.
A Domino Process toward Functionally Dense Quaternary Carbons through Pd-Catalyzed Decarboxylative C(sp3)-C(sp3) Bond Formation
Guo, Wusheng,Kuniyil, Rositha,Gómez, José Enrique,Maseras, Feliu,Kleij, Arjan W.
, p. 3981 - 3987 (2018)
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.
Pd-Catalyzed Umpolung of π-Allylpalladium Intermediates: Assembly of All-Carbon α-Vinyl Quaternary Aldehydes through C(sp3)-C(sp3) Coupling
Wang, Huifei,Qiu, Shuxian,Wang, Sasa,Zhai, Hongbin
, p. 11960 - 11965 (2018)
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.
Asymmetric Catalytic Vinylogous Addition Reactions Initiated by Meinwald Rearrangement of Vinyl Epoxides
Dong, Shunxi,Feng, Xiaoming,He, Jun,Lin, Lili,Song, Yanji,Xu, Jinxiu
supporting information, p. 14521 - 14527 (2021/05/21)
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.
Rhodium-Catalyzed Regioselective Hydroformylation of Alkynes to α,β-Unsaturated Aldehydes Using Formic Acid
Fan, Chao,Hou, Jing,Chen, Yu-Jia,Ding, Kui-Ling,Zhou, Qi-Lin
supporting information, p. 2074 - 2077 (2021/04/05)
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.
Binuclear Pd(I)-Pd(I) Catalysis Assisted by Iodide Ligands for Selective Hydroformylation of Alkenes and Alkynes
Zhang, Yang,Torker, Sebastian,Sigrist, Michel,Bregovi?, Nikola,Dydio, Pawe?
supporting information, p. 18251 - 18265 (2020/11/02)
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.
Synthetic Strategy for Tetraphenyl-Substituted All-E-Carotenoids with Improved Molecular Properties
Chung, Wook-Jin,Jung, Hyunuk,Koo, Sangho,Lim, Boram,Park, Myeongnam,Yang, Huijeong,Yoo, Hyebin
, (2020/03/13)
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.
Vinylethylene Carbonates as α,β-Unsaturated Aldehyde Surrogates for Regioselective [3 + 3] Cycloaddition
Xu, Yi,Chen, Lu,Yang, Yu-Wen,Zhang, Zhiqiang,Yang, Weibo
supporting information, p. 6674 - 6678 (2019/09/03)
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.
Ligand-controlled regiodivergent π-allyl palladium catalysis enables a switch between [3+2] and [3+3] cycloadditions
Xia, Yu,Bao, Qiao-Fei,Li, Yuke,Wang, Li-Jing,Zhang, Bo-Sheng,Liu, Hong-Chao,Liang, Yong-Min
supporting information, p. 4675 - 4678 (2019/05/02)
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.
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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Paragraph 0130-0133, (2019/02/27)
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
