22668-99-1Relevant articles and documents
Expanded Kekulenes
Fan, Wei,Han, Yi,Hou, Xudong,Wang, Xuhui,Wu, Jishan
, p. 13908 - 13916 (2021)
The synthesis of kekulene and its higher homologues is a challenging task in organic chemistry. The first successful synthesis and characterization of the parent kekulene were reported by Diederich and Staab in 1978. Herein, we report the facile preparati
Organocatalytic Activation of the Leaving Group in the Intramolecular Asymmetric SN2′ Reaction
Kuroda, Yusuke,Harada, Shingo,Oonishi, Akinori,Yamaoka, Yousuke,Yamada, Ken-Ichi,Takasu, Kiyosei
, p. 8263 - 8266 (2015)
A Bronsted-acid-catalyzed intramolecular enantioselective SN2′ reaction was developed utilizing trichloroacetimidate as a leaving group. The findings indicated that dual activation of the substrates is operative. This metal-free allylic alkylat
Dimenthylphosphine P-Oxide as a Synthetic Platform for Bulky and Chiral Ligands with Dimenthylphosphino Donor Groups
Reinhardt, Katja,Koller, Sebastian,Klein, Philippe,Lossin, Corvin,Gatzka, Julia,Altmann, Philipp J.,P?thig, Alexander,Hintermann, Lukas
, p. 1 - 19 (2022/01/12)
Attaching di(1R)-menthylphosphino fragments (menthyl = Men = 1R,2S,5R-2-isopropyl-5-methylcyclohex-1-yl) to molecular scaffolds turns them into homochiral, bulky, electron-rich phosphine ligands with proven and potential applications in coordination chemistry and transition-metal catalysis. Dimenthylphosphine P-oxide (Men2POH; 1) is established as a platform chemical toward dimenthylphosphino-containing targets via transformation to the known ligand precursors dimenthylchlorophosphine (4) and dimenthylphosphine (6). Transformations of 1 to dimenthylphosphinyl chloride (5) and dimenthylphosphinic acid (8) are elaborated. A phospha-Michael type 1,4-addition of 1 to p-benzo-or 1,4-naphthoquinone gives the corresponding o-hydroxyaryl(dimenthyl)phosphine oxides. Deprotonation of 1 with n-BuLi provides a phosphinyl nucleophile, whose reactions with alkyl halides or 1,n-dihaloalkanes provide tertiary alkyl dimenthylphosphine oxides or 1,n-bis(dimenthylphosphino)alkane bis(P-oxides) 10a-c, respectively. As an example, oxide 10b was deoxygenated to the diphosphine Men2P(CH2)3PMen2 (11) and characterized via the square-planar complex [(Men2P(CH2)3PMen2)PdCl2] (12). A selection of P-aryl dimenthylphosphines, including PhP(Men)2 (19) and 2-ClC6H4P(Men)2 (22), as well as the menthyl analogues Men-JohnPhos (21) and Men-SPhos (24), of the respective Buchwald ligands have been prepared. The combination of the secondary phosphine oxide (SPO) 1 with PdCl2 produces halide-bridged [(Men2POH)2Pd2Cl2] (25), mononuclear [(Men2POH)2PdCl2] (26), or the halide-bridged pseudochelate complex [(Men2PO···H···OPMen2)2Pd2Cl2] (27), depending on the reaction stoichiometry and conditions, all of which have been crystallographically characterized. The new ligands 1, 19, 21, 22, and 24 and complexes 25 and 26 have been evaluated in model palladium-catalyzed C-C-and C-N-fragment coupling reactions and found to display specific reactivity profiles due to the presence of the menthyl groups. Ligand 22 in particular catalyzed an asymmetric biaryl-forming coupling to give 2-methoxy-1,1′-binaphthalene with an er of up to 93:7.
Organocopper cross-coupling reaction for C-C bond formation on highly sterically hindered structures
Oi, Miku,Takita, Ryo,Kanazawa, Junichiro,Muranaka, Atsuya,Wang, Chao,Uchiyama, Masanobu
, p. 6107 - 6112 (2019/06/27)
We describe a powerful, broadly applicable cross-coupling protocol that enables carbon-carbon bond formation at highly sterically hindered carbon centers (both sp2 and sp3) by employing organocopper reagents under palladium catalysis. Experimental studies and theoretical calculations indicated that the key to the unique reactivity of copper is the relatively low activation energy of the compact transmetalation transition state, due to Cu(i)-Pd(ii) interaction, which is associated with small values of deformation energy of the reactants. This reaction is applicable to a variety of bulky substrates, including compounds inert to previous cross-coupling chemistry and has high functional group tolerance.
NOVEL CHIRAL DIHYDROBENZOOXAPHOSPHOLE LIGANDS AND SYNTHESIS THEREOF
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Paragraph 0300, (2018/06/15)
This invention relates to novel phosphorous ligands useful for organic transformations. Methods of making and using the ligands in organic synthesis are described. The invention also relates to processes for preparing the novel ligands.
2: A highly hindered pre-catalyst for the synthesis of tetra-ortho-substituted biaryls via Grignard reagent cross-coupling
Lesieur, Mathieu,Slawin, Alexandra M. Z.,Cazin, Catherine S.J.
supporting information, p. 5586 - 5589 (2014/07/22)
The new well-defined catalyst [Pd(μ-Cl)Cl(IPr*)]2 enables the efficient Grignard reagent cross-coupling for the synthesis of tetra-ortho-substituted biaryls. The high reactivity of the complex is associated with the important bulkiness of the I
Negishi cross-coupling reaction catalyzed by an aliphatic, phosphine based pincer complex of palladium. biaryl formation via cationic pincer-type Pd IV intermediates
Gerber, Roman,Blacque, Olivier,Frech, Christian M.
experimental part, p. 8996 - 9003 (2011/10/31)
The aliphatic, phosphine-based pincer complex [(C10H 13-1,3-(CH2P(Cy2)2)Pd(Cl)] (1) is a highly active Negishi catalyst, enable to quantitatively couple various electronically activated, non-activated, deactivated, sterically hindered and functionalized aryl bromides with various diarylzinc reagents within short reaction times and low catalyst loadings. Experimental observations strongly indicate that a molecular mechanism is operative with initial chloride dissociation of 1 and formation of the cationic T-shaped 14e- complex [(C10H13-1,3-(CH2P(C6H 11)2)2)Pd]+ (B), which undergoes oxidative addition of an aryl bromide (Ar′Br) to yield the cationic, penta-coordinated aryl bromide pincer complexes of type [(C10H 13-1,3-(CH2P(Cy2)2)Pd(Br) (aryl′)]+ (C) with the metal center in the oxidation state of +IV and the aryl unit in cis position relative to the aliphatic pincer core. Subsequent transmetalation with Zn(aryl)2 result in the cationic diaryl pincer complexes of type [(C10H13-1,3-(CH 2P(Cy2)2)Pd(aryl)(aryl′)]+ (D), which reductively eliminate the coupling products, thereby regenerating the catalyst. The neutral square planar aryl pincer complex - a possible key intermediate in the catalytic cycle - was found to be reversibly formed in the reaction mixture but is not involved in the catalytic mechanism. Similarly, palladium nanoparticles as the catalytically active form of 1 could have been excluded. The Royal Society of Chemistry 2011.
Synthesis of tetra-ortho-substituted biaryls using aryltriolborates
Li, Gao-Qiang,Yamamoto, Yasunori,Miyaura, Norio
, p. 1769 - 1773 (2011/09/12)
Tetra-ortho-substituted biaryls were synthesized by cross-coupling between 2,6-disubstituted bromoarenes and aryltriolborates possessing substituents at ortho carbon. The use of a copper(I) halide such as CuCl (20 mol%) with a palladium catalyst was found