Recent Progress in Homogeneous and Heterogeneous Pd Catalyst Systems for Suzuki‐Miyaura Coupling in the Absence of Added Base

Suzuki‐Miyaura coupling reaction (SMC) is an efficient method for constructing C─C bonds. In general, SMC needs a stoichiometric amount of base. Additive‐bases play important roles in activating boron reagents and replacing halide in the coordination sphere of the Pd, resulting in the formation of neutral salts. However, the use of additive‐bases causes problems: increasing byproducts, protodeboronation of several arylboronic acids and their derivatives. Performing SMC without an additive base is a straightforward strategy to avoid these base‐induced issues. Recently, several groups have addressed this challenge, and their approaches can be categorized into several types, including (i) the use of alternatives to additive bases, (ii) the use of unique electrophiles instead of simple aryl halides, and (iii) biphasic systems composed of hydrophobic surface and hydrophilic solvent for the SMC of simple aryl halides and boron reagents. In this review, we summarize additive‐base‐free SMC and clearly highlight their features.