54226-01-6Relevant academic research and scientific papers
Platinum-catalyzed anti-stereocontrolled ring-opening of oxabicyclic alkenes with Grignard reagents
Yang, Dingqiao,Liang, Ni
, p. 2080 - 2086 (2014)
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.
Phosphoramidite Ligands Based on Simple 1,2-Diols: Synthesis, Use in Copper-Catalyzed Asymmetric Additions, and Achirotopic Stereogenic Phosphorus Centres
Mistry, Nisha,Fletcher, Stephen P.
, p. 2489 - 2496 (2016/08/16)
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.).
Iridium/Copper Co-catalyzed Anti-Stereoselective Ring Opening of Oxabenzonorbornadienes with Grignard Reagents
Cheng, Guo,Yang, Wen,Li, Yue,Yang, Dingqiao
, p. 7817 - 7823 (2016/10/03)
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.
Ruthenium-catalyzed isomerization of oxa/azabicyclic alkenes: An expedient route for the synthesis of 1,2-naphthalene oxides and imines
Villeneuve, Karine,Tam, William
, p. 3514 - 3515 (2007/10/03)
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
Copper-catalyzed ring-opening of heterobicyclic alkenes with Grignard reagents: Remarkably high anti-stereocontrol
Arrayas, Ramon Gomez,Cabrera, Silvia,Carretero, Juan Carlos
, p. 1205 - 1219 (2007/10/03)
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.
Copper-catalyzed anti-stereocontrolled ring opening of oxabicyclic alkenes with Grignard reagents
Gomez Arrayas, Ramon,Cabrera, Silvia,Carretero, Juan C.
, p. 1333 - 1336 (2007/10/03)
(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.
