Hollow organic polymeric nano-bowls-supported BINOL-derived chiral phosphoric acid: enhanced catalytic performances in the enantioselective allylation of aromatic aldehydes

Regioselective Substitution of BINOL

1,1'-Bi-2-naphthol (BINOL) has been extensively used as the chirality source in the fields of molecular recognition, asymmetric synthesis, and materials science. The direct electrophilic substitution at the aromatic rings of the optically active BINOL has been developed as one of the most convenient strategies to structurally modify BINOL for diverse applications. High regioselectivity has been achieved for the reaction of BINOL with electrophiles. Depending upon the reaction conditions and substitution patterns, various functional groups can be introduced to the specific positions, such as the 6-, 5-, 4-, and 3-positions, of BINOL. Ortho-lithiation at the 3-position directed by the functional groups at the 2-position of BINOL have been extensively used to prepare the 3- and 3,3'-substituted BINOLs. The use of transition metal-catalyzed C-H activation has also been explored to functionalize BINOL at the 3-, 4-, 5-, 6-, and 7-positions. These regioselective substitutions of BINOL have allowed the construction of tremendous amount of BINOL derivatives with fascinating structures and properties as reviewed in this article. Examples for the applications of the optically active BINOLs with varying substitutions in asymmetric catalysis, molecular recognition, chiral sensing and materials are also provided.

Hollow, mesoporous, eutectic Zn1−xMgxO nano-spheres as solid acid–base catalysts for the highly regio-selective O-methylation of 1,2-diphenols

Hollow, mesoporous and eutectic Zn1−xMgxO nanospheres promote the highly selective O-methylation of 1,2-diphenols to afford mono-ethers in complete conversion together with excellent mono-ether selectivities via single-site activation model.