Categories: C-O Bond Formation >
Synthesis of aryl ethers
A vast rate increase has been achieved by the use of high concentration combined with sonication in the Mitsunobu reaction of phenols with alcohols where at least one substrate is sterically demanding.
S. D. Lepore, Y. He, J. Org. Chem., 2003, 68, 8261-8263.
The combination of trimethyl phosphate (TMP) and Ca(OH)2 enables a mild and efficient heteroatom methylation in DMF, water, or under neat conditions, at 80 °C or at room temperature. A series of O-, N-, and S-nucleophiles, including phenols, sulfonamides, N-heterocycles, such as 9H-carbazole, indole derivatives, and 1,8-naphthalimide, and aryl/alkyl thiols, are suitable substrates.
Y. Tang, B. Yu, Synthesis, 2022, 54, 2373-2390.
A consecutive detosylation/alkylation transformation of tosylated indoles and phenols with alkoxides/alcohols as the alkylation reagents features mild reaction conditions, high ipso-selectivity, and good functional group tolerance. A one-pot selective N-alkylation of unprotected indoles with alcohols and TsCl is also realized.
M.-H. Zhu, C.-L. Yu, Y.-L. Feng, M. Usman, D. Zhong, X. Wang, N. Nesnas, W.-B. Liu, Org. Lett., 2019, 21, 7073-7077.
Use of a solvent with greater density than the fluorous phase is an alternative to the U-tube method in phase-vanishing reactions in cases where both reactants are less dense than the fluorous phase.
N. K. Jana, J. G. Verkade, Org. Lett., 2003, 5, 3787-3790.
A one-pot method for the preparation of alkyl aryl ethers from aryl halides and the preparation of substituted benzofurans via a Pd-catalyzed phenol formation/cyclization protocol starting from 2-chloroaryl alkynes are described.
K. W. Anderson, T. Ikawa, R. E. Tundel, S. L. Buchwald, J. Am. Chem. Soc., 2006, 128, 10694-10695.
For a selective hydroxylation of aryl iodides and aryl bromides with tetrabutylammonium hydroxide pentahydrate, a combination of copper(I) iodide and 8-hydroxyquinaldine in a mixture of dimethyl sulfoxide and water is used. The resulting phenols can be readily reacted with alkyl and allyl halides in situ to provide the corresponding alkyl or allyl aryl ethers in high yields.
R. Paul, M. A. Ali, T. Punniyamurthy, Synthesis, 2010, 4268-4272.
A convenient and efficient protocol for the cross-coupling of phenols and vinyl halides by a unique Ni/Cu catalytic system provides an easy access to a library of aryl-vinyl and aryl-styrenyl ethers. The reaction is catalyzed by Ni and Cu is involved in the transmetalation process.
D. Kundu, P. Maity, B. C. Ranu, Org. Lett., 2014, 16, 1040-1043.
A simple addition of phenols, carboxylic acids, and protected amines to olefins can be catalyzed by triflic acid. A low concentration of triflic acid and control of the reaction temperature help to tolerate functional groups, such as methoxyl substitution on aromatics.
Z. Li, J. Zhang, C. Brouwer, C.-G. Yang, N. W. Reich, C. He, Org. Lett., 2006, 8, 4175-4178.
A catalytic amount of Pd(η3-C3H5)Cp and DPEphos as ligand efficiently converted aryl benzyl carbonates into benzyl-protected phenols through a decarboxylative etherification. Alternatively, the nucleophilic substitution of benzyl methyl carbonates with phenols proceeded in the presence of the catalyst, yielding aryl benzyl ethers.
R. Kuwano, H. Kusano, Org. Lett., 2008, 10, 1795-1798.
An enantioselective and regioselective allylic etherification of various sodium and lithium aryloxides with achiral (E)-cinnamyl and terminal aliphatic allylic electrophiles in the presence of 2 mol% of an iridium-phosphoramidite complex provides chiral allylic aryl ethers in high yields and excellent levels of regio- and enantioselectivity.
F. Lopez, T. Ohmura, J. F. Hartwig, J. Am. Chem. Soc., 2003, 125, 3426-3427.
The allylic amination and etherification of a broad range of allylic carbonates occurred in high yields and with high regioselectivities and enantioselectivities with an activated metallacyclic iridium catalyst containing a bis-naphthethylamino group.
A. Leitner, C. Shu, J. F. Hartwig, Org. Lett., 2005, 7, 1093-1096.