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.