Synthesis
Many methods in ester synthesis can also be applied to that of lactones. In one industrial synthesis of oxandrolone the key lactone-forming step is an organic reduction - esterification:
In halolactonization, an alkene is attacked by a halogen via electrophilic addition with the cationic intermediate captured intramolecularly by an adjacent carboxylic acid (See also iodolactamization), for example in this iodolactonization:
Specific methods include Yamaguchi esterification and nucleophilic abstraction.
A recent study has isolated β-lactones from bromination of 2,3-dimethylmaleate and/or 2,3-dimethylfumarate disodium salts, under ambient and aqueous conditions. The carboxylate groups of the maleate and fumarate moieties exhibit neighbouring group effects and alpha-lactones are proposed in the detailed mechanism.
Read more about this topic: Lactone
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