Concept explainers
Lactonization Methods
In Section we saw that hydroxy substituted
Many natural products are lactones, and chemists have directed substantial attention to developing alternative methods for their synthesis. The most successful of these efforts are based on electrophilic addition to the double bond of unsaturated carboxylic acids. For a generalized electrophilic reagent and, such reactions give a
Although the curved arrows show the overall electron flow, the mechanism depends on the electrophilic reagent and normally involves more than one step.
In iodolactonization the electrophilic atom, and represents a source of electrophilic iodine, usually or. In phenylselenolactonization, and is benzeneselenenyl chloride. Anti addition is observed in both iodo andphenylselenolactonization.
Both iodo andphenylselenolactonization offer the advantage of giving a product containing a
In eliminations of this type, H is always removed from the carbon to selenium that is remote from the lactone oxygen. Elimination is syn.
What is the structure of the
()? Anti addition to the triple bond occurs.
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Organic Chemistry - Standalone book
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- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning