Pyrolysis of Sulfones as a Synthetic Method [New synthetic methods (28)]

Cyclic sulfoness containing structural elements such as aromtic rings, heteroatoms. functional groups, and further SO2‐groups as ring members decompose on heating with cleavage of SO2 and formation of a new CC bond. In the last decade this “sulfone pyrolysis” has been expanded into a generally applicable method even allowing the synthesis of sterically strianed medium‐membered and multi‐membered cyclic and polycyclic systems containing aromatic ring. By the pyrolysis of sulfones which are only unilateally activated by benzyl moieties, aromatic systms can be bridged by (CH2)n chains of any desired length. In addition, (CH2) chains can be split off together with two SO2 molecules, with recombination of the remaining centers, resulting in ring contraction by four to n atoms. However, sulfone pyrolysis is of importance not only as a ring‐contraction method but as a crucial final step in the synthesis of multi‐membered hydrocarbon cycles, e.g. of the phane type.