Palladium-catalyzed C–O bond formation: direct synthesis of phenols and aryl/alkyl ethers from activated aryl halides

Palladium-catalysed hydroxylation and alkoxylation

“…Remarkably, the application of ligand 16 resulted in more stable complexes than with ligand 15. The authors assume a faster C-O reductive elimination step of the LPdAr(OH) intermediate for ligand 16. Moreover, the protocol was embedded in the synthesis of substituted benzofurans applying 2-chloroaryl alkynes as starting material and Pd 2 (dba) 3 /15 or 16 was applied as a tandem catalyst.…”

“…16 The application of an in situ catalyst composed of easily accessible Pd 2 (dba) 3 and tri-tert-butyl phosphane (21) allows the efficient synthesis of phenols. It was observed that arylphosphanes resulted in lower yields compared to alkyl phosphanes.…”

Selective One‐Pot Access to Symmetrical or Unsymmetrical Diaryl Ethers by Copper‐Catalyzed Double Arylation of a Simple Oxygen Source

“…These methods, which suffer from drawback as a result of the synthesis of only symmetric ethers, use palladium catalytic systems. [5,6] We report herein a novel method that affords selective one-pot access to symmetrical or unsymmetrical diaryl ethers by Cu-catalyzed double arylation of an oxygen source (hydroxide salts or water) by aryl halides.…”

“…[5,6] Although symmetrical diaryl ethers are very interesting substrates, unsymmetrical examples are of even greater interest. These were examined next.…”

“…However, with DMSO as solvent (conditions as in Table 1, entry 4), we were pleased to obtain various unsymmetrical diaryl ethers 11-16 selectively in good yields. These were synthesized from aromatic iodides substituted by electron-withdrawing or electron-donating groups and introduced in equimolecular amounts (Table 3, entries [1][2][3][4][5][6]. Under similar conditions, many unsymmetrical diaryl ethers such as 11-23 were obtained in good to excellent yields (Table 3, entries 7-18) by cross-coupling of various aryl iodides, with either aryl bromides or even less reactive aryl chlorides, substituted by electronwithdrawing or -donating groups.…”