Chan-Evans-Lam cross coupling

What is Chan-Evans-Lam cross coupling?

The Chan-Evans-Lam cross coupling, also kown as Chan-Lam coupling, enables the formation of aryl carbon-heteroatom bonds by using oxidative coupling of arylboronic acids, stannanes, or siloxanes with compounds that contain N-H or O-H in the presence of air.

Chan-Evans-Lam cross coupling - Chan-Lam coupling
Chan-Evans-Lam cross coupling

Y = NR’, O, S, NCOR’, NSO2R’

The substrates that can be used for this reaction include phenols, amines, anilines, amides, imides, ureas, carbamates, and sulfonamides. Copper(II) in a stoichiometric amount or a catalytic amount of copper catalyst can induce the reaction and get reoxidized by atmospheric oxygen. One advantage of the Chan-Evans-Lam cross coupling is that it can be carried out at room temperature in air, which sets it apart from the Buchwald-Hartwig cross-coupling.

Oxygen also aids in the reaction that involves a stoichiometric amount of copper(II) since the reductive elimination from a copper(III) species is more rapid.