Asymmetric Palladium-Catalyzed Intramolecular a-Arylation of Aldehydes-

Reaction Scheme


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.



PHENOL ARYLATION: A screw-top test tube equipped with a magnetic stir bar and fitted with a Teflon septum was charged with aryl halide (1.00 mmol, 1.00 equiv), phenol (1.50 mmol, 1.50 equiv), K3PO4 (318 mg, 1.50 mmol, 1.50 equiv) and LucaPhos-Pd-G3 (1 � 2 mol %). The tube was sealed and evacuated and backfilled with argon. This sequence was repeated a total of three times, after which toluene (0.6 mL) and 1, 2-dimethoxyethane (0.4 mL) were added by syringe. The reaction mixture was stirred at room temperature or 60 �C for 16 � 24 h. After completion the reaction mixture was cooled to room temperature, diluted with diethyl ether (5 mL) and eluted through a plug of silica with additional diethyl ether. The crude reaction mixture was concentrated with the aid of a rotary evaporator and purified by flash chromatography.



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