22706-20-3Relevant articles and documents
Chan-Evans-Lam Couplings with Copper Iminoarylsulfonate Complexes: Scope and Mechanism
Hardouin Duparc, Valérie,Bano, Guillaume L.,Schaper, Frank
, p. 7308 - 7325 (2018/07/05)
Copper(II) pyridyliminoarylsulfonate complexes with chloride or triflate counteranions were employed in Chan-Evans-Lam (CEL) couplings of N-nucleophiles and arylboronic acids. The complexes avoided typical side reactions in CEL couplings, and an excess of boronic acid was not required. Water was tolerated, and addition of neither base nor other additives was necessary. Primary amines, acyclic and cyclic secondary amines, anilines, aminophenol, imidazole, pyrazole, and phenyltetrazole can be quantitatively arylated at either 25 or 50 °C with 2.5 mol % of the catalyst. Reaction kinetics were investigated in detail. Kinetic and spectroscopic studies provide evidence for the formation of unproductive copper-substrate complexes. Formation of an aniline-phenylboronic acid adduct was responsible for the zero-order dependence of reaction rates on phenylboronic acid concentration. Kinetic evidence indicates that the order of reaction steps is transmetalation, nucleophile coordination, and oxidation. Couplings performed poorly with electron-deficient arylboronic acids, due to a slower Cu(II)/Cu(III) oxidation in the catalytic cycle. Photoredox catalysis partially resolved this problem, but addition of copper acetate as an external oxidant proved to be more efficient.
One-Pot Reactions for Synthesis of 2,5-Substituted Tetrazoles from Aryldiazonium Salts and Amidines
Ramanathan, Mani,Wang, Yu-Hao,Liu, Shiuh-Tzung
supporting information, p. 5886 - 5889 (2015/12/11)
One-pot sequential reactions of aryldiazonium salts with amidines followed by the treatment of I2/KI under basic conditions provide 2,5-disubstituted tetrazoles in moderate to excellent yields. This one-pot synthesis has several advantages such as mild reaction conditions, short reaction time, convenient workup, and high yields, making this methodology practical.