- Twofold C?H Activation-Based Enantio- and Diastereoselective C?H Arylation Using Diarylacetylenes as Rare Arylating Reagents
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C?H bond activation has been established as an attractive strategy to access axially chiral biaryls, and the most straightforward method is direct C?H arylation of arenes. However, the arylating source has been limited to several classes of reactive and bulky reagents. Reported herein is rhodium-catalyzed 1:2 coupling of diarylphosphinic amides and diarylacetylenes for enantio- and diastereoselective construction of biaryls with both central and axial chirality. This twofold C?H activation reaction stays contrast to the previously explored Miura–Satoh type 1:2 coupling of arenes and alkynes in terms of chemoselectivity and proceeded under mild conditions with the alkyne acting as a rare arylating reagent. Both C?H activation events are stereo-determining and are under catalyst control, with the 2nd C?H activation being diastereo-determining in a remote fashion. Analysis of the stereochemistry of the major and side products suggests moderate enantioselectivity of the initial C?H activation–desymmetrization process. However, the minor (R) rhodium vinyl intermediate is consumed more readily in undesired protonolysis, eventually resulting in high enantio- and diastereoselectivity of the major product.
- Hu, Panjie,Kong, Lingheng,Li, Xingwei,Wang, Fen,Zhu, Xiaolin
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supporting information
p. 20424 - 20429
(2021/08/09)
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- Palladium-Catalyzed Cascade C?O Cleavage and C?H Alkenylation of Phosphinyl Allenes: An Expeditious Approach to 3-Alkenyl Benzo[b]phosphole Oxides
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A phosphine oxide-directed intramolecular cyclization of phosphinyl allenes is established for the first time. The palladium-catalyzed intramolecular cyclization provides an unprecedented cascade C?O cleavage and direct C?H alkenylation toward novel 3-alk
- Liu, Teng,Sun, Xue,Wu, Lei
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supporting information
p. 2005 - 2012
(2018/03/27)
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- Development of efficient and reusable diarylphosphinopolystyrene-supported palladium catalysts for C-C bond forming cross-coupling reactions
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Short and versatile syntheses of reusable diarylphosphinopolystyrene- supported palladium catalysts 3a-j are described. The bis(o-tolyl)phosphino catalyst 3b is particularly efficient for the Suzuki and Sonogashira cross-couplings, whereas the bis(m-tolyl)phosphino catalyst 3c is the most active catalyst for Heck reactions. The couplings are performed under non-anhydrous reaction conditions and require only low amounts of supported palladium (0.5 mequivs. for Suzuki-Miyaura, 1.0 mequiv. for Sonogashira and 0.5 mequivs. for Heck reactions could be sufficient). Catalysts 3a-j are recovered by filtration and can be reused more than four times with no loss of efficiency.
- Schweizer, Stephane,Becht, Jean-Michel,Le Drian, Claude
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p. 1150 - 1158
(2008/03/28)
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