23sigmatropic

23sigmatropic refers to a specific type of sigmatropic rearrangement reaction in organic chemistry. A sigmatropic rearrangement is a pericyclic reaction where a sigma bond shifts its position within a molecule while simultaneously forming a new sigma bond. The "2,3" in 23sigmatropic denotes the positions of the atoms involved in the migration. Specifically, it indicates that a substituent migrates from the second atom in a conjugated pi system to the third atom in that same conjugated pi system. This process is often accompanied by a change in the bonding within the pi system. These reactions are generally concerted, meaning they occur in a single step without any intermediates. The stereochemistry of the migrating group is often retained during the rearrangement. 23sigmatropic rearrangements are important in organic synthesis for their ability to create new carbon-carbon or carbon-heteroatom bonds and are often employed in the construction of complex molecular architectures. Examples of common 23sigmatropic rearrangements include the Cope rearrangement and the Claisen rearrangement, although these specific named reactions are technically classified differently due to the nature of the pi systems involved. The driving force for these reactions often comes from the formation of a more stable product or the relief of strain.