Synthetic Methods of α-Pyridinyl and α-Bipyridinyl Alcohols and α,α'-Pyridine and α,α'-Bipyridine Diols

Other than their valuable use as starting materials and intermediates in the synthesis of drugs and other important organic compounds, pyridinyl alcohols are largely used as hemilabile chiral chelating ligands in the development of homogeneous transition metal catalysts. The pyridinyl alcohols covered in this review are divided into four types based on the position of the alcohol group and number of the pyridine ring, namely α-pyridinyl alcohols, α,α- pyridinyl diols, α-bipyridinyl alcohols and α,α-bipyridinyl diols. Many synthetic procedures have been conducted by a number of research groups in order to obtain the best synthetic method for these alcohols in the past decades. Significant and remarkable efforts, by many chemists, have been made to synthesise enantiomerically pure pyridinyl alcohols in very good to excellent chemical and optical yields. In this article, a critical overview of the synthetic strategies of the aforementioned pyridinyl alcohols with detailed procedures is provided with the aim of giving a wide scope for the reader in this area.