Synthesis of Dibenzofurans
Palladium catalysis enables an intramolecular cyclisation of ortho-diazonium salts of diaryl ethers to give dibenzofurans. The protocol uses 3 mol% palladium acetate as the catalyst in refluxing ethanol in the absence of base.
Z. Du, J. Zhou, C. Si, W. Ma, Synlett, 2011, 3023-3025.
An intramolecular palladium(II)-catalyzed oxidative carbon-carbon bond formation under air in the presence of pivalic acid as the reaction solvent, instead of acetic acid, results in greater reproducibility, higher yields, and broader substrate scope. The reaction allows the conversion of both electron-rich and electron-deficient diarylamines.
B. Liégault, D. Lee, M. P. Huestis, D. R. Stuart, K. Fagnou, J. Org. Chem., 2008, 73, 5022-5028.
An efficient method for the synthesis of dibenzofurans from o-iododiaryl ethers is catalyzed by reusable Pd/C under ligand-free conditions. Synthesis of o-iododiaryl ether was achieved in one pot through sequential iodination and O-arylation of phenol under mild reaction conditions.
N. Panda, I. Mattan, D. K. Nayak, J. Org. Chem., 2015, 80, 6590-6597.
An efficient route to carbazoles and dibenzofurans has been developed. The reaction of o-iodoanilines or o-iodophenols with silylaryl triflates in the presence of CsF to afford N- or O-arylated products is followed by a cyclization using a Pd catalyst to carbazoles and dibenzofurans in good to excellent yields. Various functional groups are tolerated.
Z. Liu, R. C. Larock, Org. Lett., 2004, 6, 3739-3741.
A novel and efficient protocol for the rapid construction of dibenzofuran motifs from 6-diazo-2-cyclohexenones and ortho-haloiodobenzenes involves one-pot Pd-catalyzed cross-coupling/aromatization and Cu-catalyzed Ullmann coupling.
H. Zhao, K. Yang, H. Zheng, R. Ding, F. Yin, N. Wang, Y. Li, B. Cheng, H. Wang, H. Zhai, Org. Lett., 2015, 17, 5744-5747.