Chemodivergent Palladium-Catalyzed Processes: Role of Versatile Ligands
نویسندگان
چکیده
Whereas the reaction of norbornadiene with terminal alkynes in presence of a phosphapalladacycle catalyst yields to the formation of hydroalkynation products, the use of phosphinous acid-phosphinito-containing palladium complexes gave rise to formal [2+1] cycloadducts. An experimental and computational approach was employed to study the mechanisms of the palladium-promoted hydroalkynation and [2+1] cycloaddition. On the one hand, experiences highlighted the crucial role of acidolysis steps on the catalytic activities. On the other hand, DFT calculations demonstrated the specificity of the phosphinito-phosphinous acid ligands, that is the non-equivalence of the two phosphorus atoms but the interchangeability of their properties. These results may have important implications for the mechanism of other palladium-catalyzed transformations especially those involving phosphapalladacycles and phosphinous acid-phosphinito-containing palladium complexes.
منابع مشابه
Acyclic diaminocarbenes: simple, versatile ligands for cross-coupling reactions.
Acyclic diaminocarbenes are found to be useful ligands for palladium catalyzed Suzuki-Miyaura, Sonogashira and Heck cross-coupling reactions of aryl/alkenyl bromides and chlorides.
متن کاملSynthesis and application of palladium precatalysts that accommodate extremely bulky di-tert-butylphosphino biaryl ligands.
A series of palladacyclic precatalysts that incorporate electron-rich di-tert-butylphosphino biaryl ligands is reported. These precatalysts are easily prepared, and their use provides a general means of employing bulky ligands in palladium-catalyzed cross-coupling reactions. The application of these palladium sources to various C-N and C-O bond-forming processes is also described.
متن کاملHighly Selective Palladium-Catalyzed Cross-Coupling of Secondary Alkylzinc Reagents with Heteroaryl Halides
The highly selective palladium-catalyzed Negishi coupling of secondary alkylzinc reagents with heteroaryl halides is described. The development of a series of biarylphosphine ligands has led to the identification of an improved catalyst for the coupling of electron-deficient heterocyclic substrates. Preparation and characterization of oxidative addition complex (L)(Ar)PdBr provided insight into...
متن کاملPreparation of the 4-hydroxytryptamine scaffold via palladium-catalyzed cyclization: a practical and versatile synthesis of psilocin.
[reaction: see text] The 4-hydroxytryptamine scaffold of psilocin was successfully prepared via palladium-catalyzed cyclization of protected N-tert-butoxycarbonyl-2-iodo-3-methoxyaniline and an appropriately substituted silyl acetylene. Removal of the protecting groups afforded psilocin in good yield.
متن کامل