Oxidation‐Reduction Condensation

This review is concerned with syntheses which can be carried out in the absence of acids and bases. In the case of condensations, i.e. the union of two or more reaction partners with elimination of simple molecules such as H 2 O or NH 3 , the combination of a weak oxidizing agent with a weak reducing agent has proven useful. A particularly suitable reagent for condensations with elimination of water is triphenylphosphane/di(2‐pyridyl)disulfane. The phosphane takes up the oxygen atom and is converted into the phosphane oxide, while the disulfane reacts with the two hydrogen atoms to form pyridinethione. Oxidation‐reduction condensations have been utilized for the preparation of, inter alia , esters, peptides, nucleotides, and macrolides.