Proton-Induced Assembly–Disassembly Modulation of Spiroborate Twin-Bowl Polymers Bearing Pyridyl Groups

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.

"Homoleptic" Tetracoordinate Boron Compounds

"Homoleptic" tetracoordinate boron compounds, in which the central boron atom links to four identical atoms, are a special and important family of boron compounds. During the past decades, they have been extensively employed in inorganic, organic, macromolecular, and materials chemistry. Many of them exhibit a diverse range of outstanding properties, and therefore, the synthesis and application of those compounds have emerged as a hot research topic in modern boron chemistry. This review summarizes and discusses the "homoleptic" tetracoordinate boron compounds, which are organized according to the kinds of atoms coordinated to the central boron.