超嵩反応剤, MAD

抄録

Since exceptionally bulky oxygenophilic organoaluminum reagent, methylaluminum bis (2, 6-di-t-butyl-4-methylphenoxide), MAD was successfully introduced for stereoselective activation of carbonyl compounds almost 10 years ago, it has been recognized widely as a highly promising Lewis acid in selective organic synthesis and also successfully applied to other field of chemistry. The key feature of MAD is the exceptional steric hindrance created by the two bulky 2, 6-di-t-butyl-4-methylphenoxy ligands which prevents it from self-association and hence makes it feasible to exist as a monomer in solution, thereby inducing the inherent oxygenophilicity of aluminum. The unique character of MAD is essentially related to the remarkable ability to recognize oxygen containing organic molecules as a Lewis acid receptor and activate certain functionalities, which could meet versatile synthetic requirements due to continuous developments of selective transformations and catalysts with high efficiency in organic synthesis. In this review, we go through the issue titled above according to the typical reaction patterns, where the crucial role of MAD shall be outlined.