640280-28-0Relevant articles and documents
Access to Silylated Pyrazole Derivatives by Palladium-Catalyzed C?H Activation of a TMS group
Mistico, Laetitia,Querolle, Olivier,Meerpoel, Lieven,Angibaud, Patrick,Durandetti, Muriel,Maddaluno, Jacques
supporting information, p. 9687 - 9692 (2016/07/14)
A simple and efficient approach to new silylated heterocycles of potential interest in medicinal chemistry is presented. A set of bromophenyl trimethylsilyl pyrazole intermediates can be transformed by direct organometallic routes into two families of regioisomeric iodoaryl substrates; using either arylzinc or aryllithium chemistry, the TMS group remains on the pyrazole ring or translocates to the aryl moiety. These two families can then be efficiently transformed into benzo silino pyrazoles thanks to a single-step cyclization relying on the Pd-catalyzed activation of a non-activated C(sp3)?H bond alpha to a silicon atom. The experimental conditions used, which are fully compatible with the pyrazole ring, suggest that this reaction evolves through a concerted metalation–deprotonation (CMD) mechanism.
Ruthenium-Catalyzed Cycloisomerization of 2,2′-Diethynyl- biphenyls Involving Cleavage of a Carbon-Carbon Triple Bond
Matsuda, Takanori,Kato, Kotaro,Goya, Tsuyoshi,Shimada, Shingo,Murakami, Masahiro
supporting information, p. 1941 - 1943 (2016/02/14)
A ruthenium complex catalyzes a new cycloisomerization reaction of 2,2′-diethynylbiphenyls to form 9-ethynylphenanthrenes, thereby cleaving the carbon-carbon triple bond of the original ethynyl group. A metal-vinylidene complex is generated from one of th
Ligand-Enabled Meta-C-H Alkylation and Arylation Using a Modified Norbornene
Shen, Peng-Xiang,Wang, Xiao-Chen,Wang, Peng,Zhu, Ru-Yi,Yu, Jin-Quan
supporting information, p. 11574 - 11577 (2015/09/28)
2-Carbomethoxynorbornene is identified as a more effective transient mediator to promote a Pd(II)-catalyzed meta-C(sp2)-H alkylation of amides with various alkyl iodides as well as arylation with previously incompatible aryl iodides. The use of a tailor-made quinoline ligand is also crucial for this reaction to proceed.
Diastereoselective Oxidative CN/CO and CN/CN Bond Formation Tandems Initiated by Visible Light: Synthesis of Fused N-Arylindolines
Morris, Scott A.,Nguyen, Theresa H.,Zheng, Nan
supporting information, p. 2311 - 2316 (2015/07/27)
The synthesis of fused N-arylindolines using visible light photoredox catalysis has been developed. We previously described that photogenerated amine radical cations generate substituted indoles through an intermediate benzylic carbocation. Herein, we expand the application of this chemistry by trapping the benzylic carbocation with tethered heteronucleophiles. The reactivity of the photogenerated benzylic carbocation is explored and applied to a range of substrates with various electronic characters and ring constraints. The method described provides C-2 and C-3 fused indolines bearing a tetrasubstituted carbon stereocenter with greater than 99:1 diastereoselectivity in moderate to good yields.
Soft propargylic deprotonation: Designed ligand enables au-catalyzed isomerization of alkynes to 1,3-Dienes
Wang, Zhixun,Wang, Yanzhao,Zhang, Liming
supporting information, p. 8887 - 8890 (2014/07/08)
By functionalizing the privileged biphenyl-2-ylphosphine with a basic amino group at the rarely explored 3′ position, the derived gold(I) complex possesses orthogonally positioned "push" and "pull" forces, which enable for the first time soft propargylic deprotonation and permit the bridging of a difference of >26 pKa units (in DMSO) between a propargylic hydrogen and a protonated tertiary aniline. The application of this design led to efficient isomerization of alkynes into versatile 1,3-dienes with synthetically useful scope under mild reaction conditions.
Asymmetric palladium-catalyzed intramolecular α-arylation of aldehydes
Garcia-Fortanet, Jorge,Buchwald, Stephen L.
supporting information; experimental part, p. 8108 - 8111 (2009/04/13)
(Chemical Equation Presented) Phoxy ligand: The first catalytic method for the asymmetric palladium-catalyzed intramolecular α-arylation of α-branched aldehydes was developed (see scheme). This process is distinguished by the high yields and enantioselectivities that can be obtained, making this protocol a useful synthetic tool for further applications.
Generation and suppression of 3-/4-functionalized benzynes using zinc ate base (TMP-Zn-ate): New approaches to multisubstituted benzenes
Uchiyama, Masanobu,Kobayashi, Yuri,Furuyama, Taniyuki,Nakamura, Shinji,Kajihara, Yumiko,Miyoshi, Tomoko,Sakamoto, Takao,Kondo, Yoshinori,Morokuma, Keiji
, p. 472 - 480 (2008/10/09)
We present full details of our new methods for preparing functionalized benzynes with lithium di-alkyl(2,2,6,6-tetramethylpiperidino)zincate (R 2Zn(TMP)Li) through deprotonative zincation as a key reaction. In this system, by choosing appropriate ligands for the zincate, either regioselective zincation of functionalized haloaromatics or the generation of substituted benzynes can be controlled in good yields with excellent chemoselectivity, using the same substrate. Zincation with tBu 2Zn(TMP)Li followed by electrophilic trapping or zincation with Me2Zn(TMP)Li followed by nucleophilic or diene trapping is shown to be a powerful tool for the chemoselective preparation of 1,2,3-/1,2,4- trisubstituted benzene derivatives. These methods offer far greater generality than previous methods for the synthesis of multifunctionalized benzenes. Computational/theoretical studies of the reaction mechanism of this unique benzyne formation indicated that preferential coordination of the dialkylzinc moiety of zincate to halogen is the reason for the reduced activation energy of the elimination, that is, for the formation of the benzyne. The role of the ligands on Zn in accelerating/decelerating the elimination is also discussed.
Palladium-catalyzed aryl amination-heck cyclization cascade: A one-flask approach to 3-substituted indoles
Jensen, Thomas,Pedersen, Henrik,Bang-Andersen, Benny,Madsen, Robert,Jorgensen, Morten
, p. 888 - 890 (2008/09/20)
(Chemical Equation Presented) Two for the price of one: A Pd/dppf-based catalyst provides access to the title compounds from 1,2-dihalogenated aromatic compounds and allylic amines in a single reaction flask. The initial aryl amination step occurs with excellent selectivity for the aryl iodide to ensure the formation of a single indole regioisomer, which can be functionalized in situ by N-arylation (see scheme). dba = dibenzylideneacetone, dppf = 1,1′-bis(diphenylphospanyl)ferrocene.
Synthesis of N-fused tricyclic indoles by a tandem [1,2] stevens-type rearrangement/1,2-alkyl migration of metal-containing ammonium ylides
Takaya, Jun,Udagawa, Shuji,Kusama, Hiroyuki,Iwasawa, Nobuharu
supporting information; experimental part, p. 4906 - 4909 (2009/02/08)
(Chemical Equation Presented) An alkyne moiety is activated efficiently with a [W(CO)6] or [ReBr(CO)5] catalyst in the presence of an amine functionality in the title reaction of N-(2-alkynylphenyl)-amines. The resulting ammonium ylides undergo rearrangement to form a variety of N-fused polycyclic indole derivatives (see scheme; n = 1,2; R = alkyl, Ph).
Synthesis of benzylisoquinoline derivatives possessing electron-withdrawing substituents on the benzene ring of the isoquinoline skeleton
Severin, René,Mujahidin, Didin,Reimer, Jessica,Doye, Sven
, p. 683 - 700 (2008/09/18)
3,4-Dihydrobenzylisoquinolines and 1,2,3,4-tetrahydrobenzyl-isoquinolines possessing electron withdrawing substituents on the benzene ring of the isoquinoline framework are easily accessible by a synthetic approach that takes advantage of a Sonogashira coupling to build up the C1-C8a bond of the isoquinoline skeleton and a Ti-catalyzed intramolecular hydroamination of an alkyne to close the heterocyclic ring.
