- Palladium-catalyzed enantioselective ring opening of oxabicyclic alkenes with organozinc halides
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Palladium-catalyzed asymmetric ring opening of oxabenzonorbornadienes with readily available organozinc halides under mild conditions in the presence of (S)-Pri-PHOX produces the corresponding 1,2-dihydronaphth-1-ols in good yield and high enan
- Li, Ming,Yan, Xiao-Xia,Hong, Wei,Zhu, Xia-Zhen,Cao, Bo-Xun,Sun, Jie,Hou, Xue-Long
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- Transition metal complexes of fesulphos ligands in enantioselective catalytic transformations
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Metal complexes of 1-phosphino-2-sulfenylferrocene (fesulphos ligands) act as highly efficient catalysts in Pd-catalyzed desymmetrization of meso heterobicyclic alkenes and in Cu-catalyzed formal aza Diels-Alder reaction of Danishefsky diene to N-sulfonyl
- Arrayas, Ramon Gomez,Mancheno, Olga Garcia,Cabrera, Silvia,Carretero, Juan Carlos
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- Iridium/Copper Co-catalyzed Anti-Stereoselective Ring Opening of Oxabenzonorbornadienes with Grignard Reagents
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Cooperative catalysis has been widely considered as one of the most powerful strategies to improve synthetic efficiency. A new iridium/copper cocatalyst was developed for the ring-opening reaction of oxabenzonorbornadienes with a wide variety of Grignard reagents, which afforded the corresponding anti-2-substituted 1,2-dihydronaphthalen-1-ols in high yields (up to 99% yield) under mild conditions. The effects of catalyst loading, Lewis acid, Grignard reagent loading, and reaction temperature on the yield were investigated. To the best of our knowledge, it represents the first example of ring-opening reactions of oxabicyclic alkenes with Grignard reagent nucleophiles in a trans-stereoselective manner.
- Cheng, Guo,Yang, Wen,Li, Yue,Yang, Dingqiao
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- Multinuclear Pd/Zn complex-catalyzed asymmetric alkylative ring-opening reaction of oxabicyclic alkenes
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A multinuclear palladium catalyst can be used to realize the efficient catalytic asymmetric alkylative ring-opening reaction of oxabicyclic alkenes using dimethylzinc. The use of (R)-BINOL-PHOS bearing bisphosphine and diol moieties is essential for achieving excellent catalytic performance; the corresponding monophosphine and hydroxy-protected derivatives showed lower catalytic activities and/or enantioselectivities. The generation of Pd/Zn-multinuclear complexes is a key feature of the present catalysis.(Figure Presented)
- Endo, Kohei,Tanaka, Keisuke,Ogawa, Mika,Shibata, Takanori
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- Nickel-catalyzed: Syn -stereocontrolled ring-opening of oxa- and azabicyclic alkenes with dialkylzinc reagents
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A new nickel-catalyzed syn-stereocontrolled ring-opening of oxa- and azabicyclic alkenes with dialkylzinc reagents was developed, which afforded the corresponding cis-2-alkyl-1,2-dihydronaphthalen-1-ols and 1,2-alkyl amide derivatives in moderate to excellent yields (up to 99% yield) under mild conditions. In this work, we successfully avoided obtaining hydride addition byproducts arising from β-hydride elimination on an ethyl nickel species. Furthermore, a plausible mechanism for the ring-opening reaction was also proposed.
- Deng, Yingying,Yang, Wen,Yao, Yongqi,Yang, Xin,Zuo, Xiongjun,Yang, Dingqiao
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p. 703 - 711
(2019/01/24)
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- Synthesis method of chiral compound of hydrogenated naphthalene structure unit
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The invention discloses a synthesis method of a chiral compound of a hydrogenated naphthalene structure unit. In a methylbenzene/water solvent system, under the existence of catalysts of palladium acetate and R-(+)-1,1'-dinaphthalene-2,2'-diphenylphosphane, potassium trifluoroborate derivatives and oxa-benzo norbornene react at the room temperature to obtain the chiral compound of the hydrogenatednaphthalene structure unit through synthesis. The method provided by the invention has the advantages that the raw materials are cheap and can be easily obtained; the reaction conditions are mild; the post treatment is simple; the obtained target product yield and ee value are high.
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Paragraph 0027; 0031; 0032
(2018/06/26)
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- Phosphoramidite Ligands Based on Simple 1,2-Diols: Synthesis, Use in Copper-Catalyzed Asymmetric Additions, and Achirotopic Stereogenic Phosphorus Centres
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Phosphoramidite ligands are widely used in catalysis and normally constructed from large C2-symmetrical diols such as BINOL or TADDOL. We report here on new ligands based on a set of simple diols that had been previously overlooked. Ligands based on (S,S)-trans-cyclohexanediol and (R,R)-(+)-1,2-diphenyl-1,2-ethanediol, in combination with both chiral and achiral amines, were tested in 3 different copper-catalyzed asymmetric reactions and up to 89% ee was observed. A different ligand gave the best results in each reaction examined. Using meso-cis-cyclohexanediol and meso-cis-diphenyl-1,2-ethanediol with a chiral non-racemic amine gave diastereomeric ligands bearing achirotopic stereogenic phosphorus atoms which were characterized with the assistance of X-ray crystallography and variable temperature NMR studies. This work provides a new set of ligands that may be useful in some asymmetric reactions when phosphoramidites based on BINOL and TADDOL are ineffective. We also identify a novel stereochemical feature of phosphoramidites that may be useful in asymmetric catalysis and ligand design. (Figure presented.).
- Mistry, Nisha,Fletcher, Stephen P.
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supporting information
p. 2489 - 2496
(2016/08/16)
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- Platinum-catalyzed anti-stereocontrolled ring-opening of oxabicyclic alkenes with Grignard reagents
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A new platinum-catalyzed anti-stereocontrolled ring-opening of oxabicyclic alkenes with various Grignard reagents was reported, which afforded the corresponding anti-2-substituted-1,2-dihydronaphthalen-1-ol products with moderate to good yields in the presence of a catalytic amount of Pt(PPh 3)4 (2.5 mol%) under mild conditions. The effects of catalyst loading, solvent and temperature on the yield were also investigated. Furthermore, the trans-configuration of the product 5i was confirmed by X-ray diffraction analysis.
- Yang, Dingqiao,Liang, Ni
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p. 2080 - 2086
(2014/03/21)
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- Relay catalysis: Enantioselective synthesis of cyclic benzo-fused homoallylic alcohols by chiral bronsted acid-catalyzed allylboration/ring closing metathesis
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Six- and seven-membered benzo-fused cyclic homoallylic alcohols can be readily synthesized by a tandem chiral Bronsted acid-catalyzed allyl (crotyl)boration/ring closing metathesis sequence performed under orthogonal relay catalysis conditions. Excellent enantio- and diastereoselectivities are obtained in most of the cases. In addition, the parent crotylboration/RCM process is also described. The required substrates, ortho-vinylbenzaldehydes, are readily available in one step from commercially available starting materials. Both catalysts and reactants are also available from commercial suppliers. The reaction shows broad functional group compatibility and is also suitable for heteroaromatic substrates. Substitution at any position of the aromatic ring is tolerated; however, substitution at position 6 results in a substantial drop in enantioselectivity. Copyright
- Fustero, Santos,Rodriguez, Elsa,Lazaro, Ruben,Herrera, Lidia,Catalan, Silvia,Barrio, Pablo
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p. 1058 - 1064
(2013/05/21)
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- Copper-catalyzed asymmetric ring-opening reaction of oxabenzonorbornadienes with Grignard and aluminum reagents
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A highly enantioselective method for the copper-catalyzed desymmetrization of oxabenzonorbornadienes with aluminum reagents and SimplePhos as chiral ligand has been developed. The same reaction with Grignard reagents is also reported. A wide range of alky
- Millet, Renauds,Gremaud, Ludovic,Bernardez, Tania,Palais, Laetitia,Alexakis, Alexandre
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experimental part
p. 2101 - 2112
(2009/12/31)
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- Copper-catalyzed desymmetrization of oxabenzonorbornadienes with aluminum reagents
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The desymmetrization of oxabenzonorbornadienes with aluminum reagents and SimplePhos as chiral ligand is described. The corresponding homoallylic alcohols are obtained in high yield, diastereoselectivity, and enantiomeric excess. Furthermore the first ant
- Millet, Renaud,Bernardez, Tania,Palais, La?titia,Alexakis, Alexandre
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experimental part
p. 3474 - 3477
(2009/09/28)
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- Optically active dinuclear palladium complexes containing a Pd-Pd bond: Preparation and enantioinduction ability in asymmetric ring-opening reactions
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Optically active dinuclear palladium complexes containing a Pd-Pd bond were prepared by using (R,R)-bis(tert-butylmethylphosphino)methane ((R,R)-t-Bu-MiniPHOS). The dinuclear palladium complexes coupled with silver triflate exhibited good to excellent ena
- Ogura, Tomokazu,Yoshida, Kazuhiro,Yanagisawa, Akira,Imamoto, Tsuneo
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supporting information; experimental part
p. 2245 - 2248
(2009/10/23)
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- Optically-active bis(alkynylphosphino) ethane-borane derivative and process for producing the same
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An optically-active bis(alkynylphosphino)ethane-borane derivative represented by formula (1): wherein R1 and R2, which may be the same or different, each represent an alkyl group, a phenyl group, an alkylsilyl group or a hydrogen ato
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Page/Page column 7
(2008/12/08)
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- Synthesis and enantioselectivity of P-chiral phosphine ligands with alkynyl groups
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(Formula Presented) A range of asymmetric transformations are catalyzed by transition-metal complexes of the title ligands with excellent enantioselectivities. The ligands, which were applied successively in Rh-catalyzed hydrogenation and Rh- or Pd-cataly
- Imamoto, Tsuneo,Saitoh, Youichi,Koide, Aya,Ogura, Tomokazu,Yoshida, Kazuhiro
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p. 8636 - 8639
(2008/09/18)
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- Palladacycle as highly efficient catalyst for ring opening of oxabicyclic alkenes with organozinc halides
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Ring opening reaction of oxabicylic alkenes 4 with in situ prepared organozinc halides 5 was catalyzed by palladacycle 3 with high efficiency. Good yields of the corresponding 1,2-dihydronaphth-1-ols (6) were provided when as low as 0.05 mol% of palladacycle 3 was used. 31P NMR study showed that the skeleton of 3 remained intact in the reaction, which implied that palladacycle 3 did not serve as a catalyst precursor but a catalyst in the reaction.
- Zhang, Ting-Ke,Yuan, Ke,Hou, Xue-Long
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p. 1912 - 1919
(2007/10/03)
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- 2, 3-Bis(dialkylphosphino)pyrazine derivative, process of producing the same, and metal complex having the same as ligand
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An optically active 2,3-bis(dialkylphosphino)pyrazine derivative represented by formula (1) is disclosed. The pyrazine derivative is preferably a quinoxaline derivative represented by formula (2). In formula (1) and (2), R1 is preferably a t-butyl or adamantyl group, and R2 is preferably a methyl group. wherein R1 is a substituted or unsubstituted, straight chain or branched alkyl group having 2 to 10 carbon atoms; R2 is a substituted or unsubstituted, straight chain or branched alkyl group having fewer carbon atoms than R1; and R3 and R4, which may be the same or different, are each a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R3 and R4 are taken together to form a saturated or unsaturated ring. wherein R1 and R2 are as defined above; and R5 is a monovalent substituent.
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Page/Page column 5
(2008/06/13)
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- Air-stable P-chiral bidentate phosphine ligand with (1-adamantyl) methylphosphino group
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Air-stable diphosphine ligand, (R,R)-2,3-bis((1-adamantyl)-methylphosphino) quinoxaline, was prepared by the reaction of enantiomerically pure (S)-(1-adamantyl)methylphosphine-borane with 2,3-dichloroquinoxaline. The ligand exhibited excellent enantiosele
- Imamoto, Tsuneo,Kumada, Atsushi,Yoshida, Kazuhiro
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p. 500 - 501
(2008/02/10)
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- Ruthenium-catalyzed isomerization of oxa/azabicyclic alkenes: An expedient route for the synthesis of 1,2-naphthalene oxides and imines
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1,2-Naphthalene oxides and imines can be rapidly accessed through a ruthenium-catalyzed isomerization of readily available 7-oxa/azabenzonorbornadienes. These mild reaction conditions were found to be tolerant to various functional groups and the isomerization is highly regioselective. Copyright
- Villeneuve, Karine,Tam, William
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p. 3514 - 3515
(2007/10/03)
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- Copper-catalyzed ring-opening of heterobicyclic alkenes with Grignard reagents: Remarkably high anti-stereocontrol
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Unlike most of the reported protocols for the ring-opening reaction of heterobicyclic alkenes with carbon nucleophiles which typically occur with syn selectivity, the alkylative ring-opening reaction of [2.2.1]oxa- and azabicyclic alkenes with Grignard reagents in the presence of a catalytic amount of copper(I) takes place with very high or complete anti-stereocontrol under smooth reaction conditions. This new procedure proved to be wide in scope with respect to both the Grignard reagent and the bicyclic alkene. Especially noteworthy is the facile ring-opening reaction of low reactive substrates such as nonaromatic oxabicyclic alkenes and azabenzonorbornadienes under this catalyst system. Georg Thieme Verlag Stuttgart.
- Arrayas, Ramon Gomez,Cabrera, Silvia,Carretero, Juan Carlos
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p. 1205 - 1219
(2007/10/03)
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- Copper-catalyzed asymmetric ring opening of oxabicyclic alkenes with Grignard reagents
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(Chemical Equation Presented) Simple Grignard reagents were applied in copper-catalyzed asymmetric ring-opening reactions of oxabenzonorbornadiene derivatives using spiro phosphoramidite ligands. Excellent anti- stereoselectivities and good enantioselecti
- Zhang, Wei,Wang, Li-Xin,Shi, Wen-Jian,Zhou, Qi-Lin
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p. 3734 - 3736
(2007/10/03)
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- An air-stable P-chiral phosphine ligand for highly enantioselective transition-metal-catalyzed reactions
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A new P-chiral phosphine ligand, (R,R)-2,3-bis(tert-butylmethylphosphino)quinoxaline, has been prepared by the reaction of enantiomerically pure tert-butylmethylphosphine-borane with 2,3-dichloroquinoxaline. This ligand, in contrast to most of the previously reported P-chiral ligands, is an air-stable solid and exhibits excellent enantioselectivities in both Rh-catalyzed asymmetric hydrogenations and Rh- or Pd-catalyzed carbon-carbon bond-forming reactions. Copyright
- Imamoto, Tsuneo,Sugita, Keitaro,Yoshida, Kazuhiro
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p. 11934 - 11935
(2007/10/03)
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- Fesulphos-palladium(II) complexes as well-defined catalysts for enantioselective ring opening of meso heterobicyclic alkenes with organozinc reagents
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The air-stable and readily available cationic methyl palladium(II) complexes of planar chiral Fesulphos ligands [(Fesulphos)Pd(Me)(PhCN)] + X- are highly efficient catalysts for the alkylative ring opening of oxa- and azabicyclic alk
- Cabrera, Silvia,Arrayas, Ramon Gomez,Alonso, Ines,Carretero, Juan C.
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p. 17938 - 17947
(2007/10/03)
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- Cationic planar chiral palladium P,S complexes as highly efficient catalysts in the enantioselective ring opening of oxa- and azabicyclic alkenes
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Open plan: Cationic methylpalladium(II) complexes of planar chiral Fesulphos ligands (Fesulphos = 1-phosphanyl-2-sulfenylferrocene) show excellent performance in the alkylative ring opening of oxa- and azabicyclic alkenes with dialkyl zinc reagents (see s
- Cabrera, Silvia,Gomez Arrayas, Ramon,Carretero, Juan C.
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p. 3944 - 3947
(2007/10/03)
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- Scope of Palladium-Catalyzed Alkylative Ring Opening
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We have explored the scope of the palladium-catalyzed nucleophilic ring opening methodology. New highly selective and highly active catalysts have been found for the ring opening of oxabenzonorbornadienes. Employing these catalysts, the addition of variou
- Lautens, Mark,Hiebert, Sheldon
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p. 1437 - 1447
(2007/10/03)
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- Copper-catalyzed anti-stereocontrolled ring opening of oxabicyclic alkenes with Grignard reagents
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(Matrix presented) A general copper-catalyzed procedure for the stereoselective ring opening of [2.2.1]-oxabicyclic alkenes with Grignard reagents is described. In the presence of catalytic amounts of CuCl/PPh 3 the reaction occurs with very high or complete anti selectivity in all cases.
- Gomez Arrayas, Ramon,Cabrera, Silvia,Carretero, Juan C.
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p. 1333 - 1336
(2007/10/03)
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- Copper phosphoramidite catalyzed enantioselective ring-opening of oxabicyclic alkenes: Remarkable reversal of stereocontrol
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An unprecedented copper phosphoramidite catalyzed enantioselective alkylative ring-opening reaction of oxabenzonorbornadiene derivatives with dialkylzinc reagents is reported. The reaction shows high levels of anti-stereoselectivity (up to anti/syn >99:1), complementary to the Pd(0)-catalyzed syn-selective ring-opening protocol, allowing a new entry to anti-dihydronaphthols with high enantioselectivity (up to 99% ee).
- Bertozzi, Fabio,Pineschi, Mauro,Macchia, Franco,Arnold, Leggy A.,Minnaard, Adriaan J.,Feringa, Ben L.
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p. 2703 - 2705
(2007/10/03)
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- 1-Phosphino-2-sulfenylferrocenes: Efficient ligands in enantioselective palladium-catalyzed allylic substitutions and ring opening of 7-oxabenzonorbornadienes
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The readily available 1-phosphino-2-sulfenylferrocenes 1 provide very high enantioselectivities in Pd-catalyzed allylic substitution reactions and alkylative ring opening of 7-oxabenzonorbornadiene with dialkylzinc reagents.
- Priego, Julian,Garcia Mancheno, Olga,Cabrera, Silvia,Gomez Arrayas, Ramon,Llamas, Tomas,Carretero, Juan C.
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p. 2512 - 2513
(2007/10/03)
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- Mechanistic studies of the palladium-catalyzed ring opening of oxabicyclic alkenes with dialkylzinc
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The mechanism of the palladium-catalyzed ring opening of oxabicyclic alkenes with dialkylzinc has been studied. Experiments which rule out a π-allyl mechanism were carried out. Trapping carbometalated products and synthesis and successful reaction of alkyl palladium species provided strong evidence in favor of an enantioselective carbopalladation as the key step in the mechanism. The studies also suggest that a cationic palladium species is responsible for carbopalladation of the alkene. The combination of palladium and dialkylzinc is unique in that the dialkylzinc functions both in the transmetalation to palladium and as a Lewis acid in forming the reactive cationic palladium species.
- Lautens,Hiebert,Renaud
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p. 6834 - 6839
(2007/10/03)
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- Nickel-catalyzed highly stereoselective ring opening of 7-oxa- and azanorbornenes with organic halides
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Nickel-catalyzed ring-opening reactions of 7-heteroatom norbornadienes and norbornenes with various organic halides to give products with multiple stereocenters are described. Treatment of 7-oxabenzonorbornadiene (1a) and 7- carbomethoxy-7-azabenzonorbornadiene (1b) with aryl iodides (ArI) in the presence of NiCI2(PPh3)2 and Zn powder gave the corresponding ring- opening addition products cis-1,2-dihydro-2-aryl-1-naphthol (2a-m) and methyl N-[cis-1,2-dihydro-2-aryl-1-naphthyl]carbamate (3a-e) completely stereoselectively in 40-99% yields. The nickel system also catalyzes the reaction of highly substituted oxabicyclic [2.2.1] compounds (1c-e) with organic halides (PhI, PhCH2Br, PhCHCHBr, and PhCBrCH2) to give the corresponding ring-opening products (4a-d, 5, 6a,b) that consist of four fixed stereocenters. Studies on the effect of solvent on the reaction of 1a with PhI show that CH3CN gives the highest yield of product 2a; no product 2a is observed when toluene, dichloromethane, methanol, DMF, or DMSO is used as solvent. Addition of extra PPh3 to the reaction mixture reduced the yield of 2a. A mechanism is proposed to account for the formation of these nickel- catalyzed ring-opening addition products.
- Feng,Nandi,Sambaiah,Cheng
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p. 3538 - 3543
(2007/10/03)
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