Barton–Kellogg reaction

Barton–Kellogg Reaction

The Barton–Kellogg Reaction is a notable chemical reaction in the field of organic chemistry, named after the British chemist Derek H.R. Barton and his American collaborator, Melville E. Kellogg. This reaction involves the synthesis of olefins (alkenes) through the coupling of two distinct fragments: a thioether and a diazo compound. The process is distinguished by its use of sulfur ylides as intermediates, leading to the formation of double bonds with high specificity and efficiency.

Reaction Mechanism

The Barton–Kellogg Reaction proceeds through a series of well-defined steps. Initially, a thioether is oxidized to a sulfoxide, which is then subjected to a photochemical reaction or treated with a base to generate a sulfur ylide. This intermediate is highly reactive and undergoes a chemical reaction with a diazo compound. The interaction between these two components results in the expulsion of nitrogen gas and the formation of an episulfonium ion. The episulfonium ion subsequently undergoes a ring-opening reaction, leading to the formation of the desired olefin and a sulfur dioxide molecule as a byproduct.

Applications

The Barton–Kellogg Reaction has found applications in various areas of organic synthesis, particularly in the construction of complex molecular architectures. Its ability to form carbon-carbon double bonds efficiently makes it a valuable tool for the synthesis of natural products, pharmaceuticals, and materials science. The reaction's specificity and the stereochemical control it offers are crucial for the synthesis of compounds with defined double bond configurations.

Limitations

Despite its utility, the Barton–Kellogg Reaction has some limitations. The requirement for specific starting materials, such as sulfoxides and diazo compounds, can sometimes pose a challenge. Additionally, the reaction conditions, especially the need for photochemical activation or strong bases, may not be compatible with all functional groups, limiting the reaction's applicability in certain contexts.

Examples

One notable example of the Barton–Kellogg Reaction is its use in the synthesis of complex natural products, where the formation of double bonds is a key step in constructing the molecule's carbon framework. This reaction has enabled chemists to synthesize a variety of compounds with intricate structures and significant biological activity.

See Also

• Olefin Metathesis
• Sulfur Ylides
• Diazo Compounds
• Photochemistry