Synthesis of Bromo-Substituted 4-Hydroxy[2.2]paracyclophanes and [2.2]Paracyclophane-4,7-quinones as Versatile Chiral Building Blocks

Approaches to a number of bromo‐substituted derivatives of 4‐hydroxy[2.2]paracyclophane, including the regioselective mono‐ and dibromination of this phenol, were investigated. The applicability of the regioisomeric monobromo‐substituted phenols for the synthesis of substituted [2.2]paracyclophane‐4,7‐quinones through a one‐pot diazonium coupling/reduction/oxidation sequence was demonstrated. The compounds obtained possess various substitution patterns and could be used for the synthesis of a wide range of [2.2]paracyclophane derivatives by transformation of the bromine, hydroxy, and quinoid fragments. The syntheses of a number of mono‐ and disubstituted 4‐hydroxy[2.2]paracyclophanes and substituted [2.2]paracyclophane‐4,7‐quinones with various substitution patterns are elaborated. The planar chiral building blocks combine bromine atoms, hydroxy groups, and/or quinoid fragments in their structures, and they are ready for further transformations (including resolution into enantiomers).