54670-80-3Relevant articles and documents
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Detweiler,Amstutz
, p. 829 (1952)
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Pd-Catalyzed Cross-Coupling Reactions Promoted by Biaryl Phosphorinane Ligands
Laffoon, Joshua D.,Chan, Vincent S.,Fickes, Michael G.,Kotecki, Brian,Ickes, Andrew R.,Henle, Jeremy,Napolitano, José G.,Franczyk, Thaddeus S.,Dunn, Travis B.,Barnes, David M.,Haight, Anthony R.,Henry, Rodger F.,Shekhar, Shashank
, p. 11691 - 11708 (2019/12/02)
We report the use of biaryl phosphorinanes as ligands for Pd-catalyzed cross-coupling reactions. A modular synthesis was developed that employs a double conjugate addition of primary biaryl phosphines into 1,1,5,5-tetraalkyl penta-1,4-diene-3-ones. Notably, this synthesis does not require the use of copper, a known contaminant in structurally related biaryl phosphane ligands. Using the synthetic strategy described above, we synthesized a library of biaryl phosphorinanes, varying their substitution about phosphorus and the steric and electronic nature of the biaryl motif. We then benchmarked their performance as ligands in Pd-catalyzed cross coupling reactions such as aryl sulfonamidation, aryl alkoxylation, and aryl amination in the presence of soluble organic bases. In each reaction studied, many ligands outperformed biaryl phosphanes known to promote the given transformation. Detailed substrate scopes were determined using high-throughput screening technology. Several biaryl phosphorinanes and their corresponding Pd(II) oxidative-addition complexes were extensively characterized using NMR spectroscopy and X-ray crystallography. General observations support that biaryl phosphorinanes promote reductive elimination and form robust catalysts with palladium. In many cases the use of these biaryl phosphorinanes may be advantageous over the use of biaryl phosphanes with respect to lower catalyst loadings, shorter reaction times, and robustness.
Breaking the Base Barrier: An Electron-Deficient Palladium Catalyst Enables the Use of a Common Soluble Base in C-N Coupling
Dennis, Joseph M.,White, Nicholas A.,Liu, Richard Y.,Buchwald, Stephen L.
supporting information, p. 4721 - 4725 (2018/04/11)
Due to the low intrinsic acidity of amines, palladium-catalyzed C-N cross-coupling has been plagued continuously by the necessity to employ strong, inorganic, or insoluble bases. To surmount the many practical obstacles associated with these reagents, we utilized a commercially available dialkyl triarylmonophosphine-supported palladium catalyst that facilitates a broad range of C-N coupling reactions in the presence of weak, soluble bases. The mild and general reaction conditions show extraordinary tolerance for even highly base-sensitive functional groups. Additionally, insightful heteronuclear NMR studies using 15N-labeled amine complexes provide evidence for the key acidifying effect of the cationic palladium center.
