21758-19-0Relevant academic research and scientific papers
Iron-Catalyzed Highly Enantioselective Hydrogenation of Alkenes
Lu, Dongpo,Lu, Peng,Lu, Zhan,Ren, Xiang,Sun, Yufeng,Xu, Haofeng
supporting information, p. 12433 - 12438 (2021/08/23)
Here, we reported for the first time an iron-catalyzed highly enantioselective hydrogenation of minimally functionalized 1,1-disubstituted alkenes to access chiral alkanes with full conversion and excellent ee. A novel chiral 8-oxazoline iminoquinoline ligand and its iron complex have been designed and synthesized. This protocol is operationally simple by using 1 atm of hydrogen gas and shows good functional group tolerance. A primary mechanism has been proposed by the deuterium-labeling experiments.
Cobalt(II)-Catalyzed Stereoselective Olefin Isomerization: Facile Access to Acyclic Trisubstituted Alkenes
Zhang, Sheng,Bedi, Deepika,Cheng, Lu,Unruh, Daniel K.,Li, Guigen,Findlater, Michael
supporting information, p. 8910 - 8917 (2020/12/23)
Stereoselective synthesis of trisubstituted alkenes is a long-standing challenge in organic chemistry, due to the small energy differences between E and Z isomers of trisubstituted alkenes (compared with 1,2-disubstituted alkenes). Transition metal-catalyzed isomerization of 1,1-disubstituted alkenes can serve as an alternative approach to trisubstituted alkenes, but it remains underdeveloped owing to issues relating to reaction efficiency and stereoselectivity. Here we show that a novel cobalt catalyst can overcome these challenges to provide an efficient and stereoselective access to a broad range of trisubstituted alkenes. This protocol is compatible with both mono- and dienes and exhibits a good functional group tolerance and scalability. Moreover, it has proven to be a useful tool to construct organic luminophores and a deuterated trisubstituted alkene. A preliminary study of the mechanism suggests that a cobalt-hydride pathway is involved in the reaction. The high stereoselectivity of the reaction is attributed to both a π-πstacking effect and the steric hindrance between substrate and catalyst.
Lewis Acid Catalyzed Transfer Hydromethallylation for the Construction of Quaternary Carbon Centers
Walker, Johannes C. L.,Oestreich, Martin
supporting information, p. 15386 - 15389 (2019/10/28)
The design and gram-scale synthesis of a cyclohexa-1,4-diene-based surrogate of isobutene gas is reported. Using the highly electron-deficient Lewis acid B(C6F5)3, application of this surrogate in the hydromethallylation of electron-rich styrene derivatives provided sterically congested quaternary carbon centers. The reaction proceeds by C(sp3)?C(sp3) bond formation at a tertiary carbenium ion that is generated by alkene protonation. The possibility of two concurrent mechanisms is proposed on the basis of mechanistic experiments using a deuterated surrogate.
Electrochemical [4+2] Annulation-Rearrangement-Aromatization of Styrenes: Synthesis of Naphthalene Derivatives
Ma, Yueyue,Lv, Jufeng,Liu, Chengyu,Yao, Xiantong,Yan, Guoming,Yu, Wei,Ye, Jinxing
supporting information, p. 6756 - 6760 (2019/04/17)
We report the first electrochemical strategy to synthesize functionalized naphthalene derivatives through [4+2] annulation—rearrangement–aromatization from styrenes under mild conditions. The electrolysis does not require metals, oxidants and high valence substrates, indicating the atom and step-economy ideals. The dehydrodimer produced through [4+2] cycloaddition of 4-methoxy α-methyl styrene is isolated and proved to be the key intermediate for the following oxydehydrogenation to form carbon cation, which undergoes rearrangement–aromatization to afford the final products. This reaction represents a powerful access to construct multi-substituted naphthalene blocks in a single step.
Nickel-catalyzed Kumada reaction of tosylalkanes with Grignard reagents to produce alkenes and modified arylketones
Wu, Ji-Cheng,Gong, Lu-Bing,Xia, Yuanzhi,Song, Ren-Jie,Xie, Ye-Xiang,Li, Jin-Heng
supporting information, p. 9909 - 9913 (2012/10/30)
Open a new door: The first example of alkene synthesis from alkyl electrophiles with Grignard reagents using the Kumada cross-coupling reaction strategy is reported. This method opens a new door for the Kumada cross-coupling reaction, allowing alkenes to be prepared from the reaction of tosylalkanes with Grignard reagents. Copyright
Stereoselective alkene isomerization over one position
Larsen, Casey R.,Grotjahn, Douglas B.
supporting information; experimental part, p. 10357 - 10360 (2012/08/08)
Although controlling both the position of the double bond and E:Z selectivity in alkene isomerization is difficult, 1 is a very efficient catalyst for selective mono-isomerization of a variety of multifunctional alkenes to afford >99.5% E-products. Many reactions are complete within 10 min at room temperature. Even sensitive enols and enamides susceptible to further reaction can be generated. Catalyst loadings in the 0.01-0.1 mol% range can be employed. E-to-Z isomerization of the product from diallyl ether was only -6 times as fast as its formation, showing the extremely high kinetic selectivity of 1.
Palladium catalyzed coupling of tosylhydrazones with aryl and heteroaryl halides in the absence of external ligands: Synthesis of substituted olefins
Ojha, Devi Prasan,Prabhu, Kandikere Ramaiah
, p. 11027 - 11033 (2013/02/22)
Palladium catalyzed cross-coupling reaction of hydrazones with aryl halides in the absence of external ligand is reported. The versatility of this coupling reaction is demonstrated in showcasing the selectivity of coupling reaction in the presence of hydr
Neutral ionic liquid [hmim]Br as a green reagent and solvent for the mild and efficient dehydration of benzyl alcohols into (E)-arylalkenes under microwave irradiation
Kumar, Rakesh,Sharma, Abhishek,Sharma, Naina,Kumar, Vinod,Sinha, Arun K.
supporting information; experimental part, p. 5577 - 5582 (2009/05/11)
A mild and efficient, ionic-liquid-assisted, green protocol for the dehydration of benzyl alcohols into the corresponding (E)-arylalkenes under microwave irradiation has been developed. The method utilizes a neutral and recyclable ionic liquid (1-hexyl-3-methylimidazolium bromide) as a reagent and solvent to cleanly provide a wide range of olefins without the need of harsh and expensive Bronsted/Lewis acids. The method was extended to the efficient conversion of acetylated/benzoylated derivatives of benzyl alcohol into their corresponding (E)-arylalkenes. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Iridium-catalyzed enantioselective hydrogenation of terminal alkenes
McIntyre, Steven,Hoermann, Esther,Menges, Frederik,Smidt, Sebastian P.,Pfaltz, Andreas
, p. 282 - 288 (2007/10/03)
Iridium complexes derived from chiral P,N ligands are efficient catalysts for the enantioselective hydrogenation of 2-aryl-substituted terminal alkenes. Using 0.1-1 mol % of catalyst at room temperature and ambient hydrogen pressure, high enantioselectivi
Synthesis of polysubstituted alkenes by Heck vinylation or Suzuki cross-coupling reactions in the presence of a tetraphosphane-palladium catalyst
Berthiol, Florian,Doucet, Henri,Santelli, Maurice
, p. 1091 - 1096 (2007/10/03)
Through the use of [PdCl(C3H5)]2/cis,cis,cis-1,2,3, 4-tetrakis[(diphenylphosphanyl)methyl]cyclopentane as a catalyst, a range of vinyl bromides undergo Suzuki cross-couplings with arylboronic acids in good yields. Furthermore, the catalyst can be used at low loadings, even for reactions of sterically hindered substrates. Mediated by this catalyst, stilbene and 1,1-diphenylethylene undergo Heck reactions with aryl halides to give triarylethylene derivatives. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
