Peterson olefination

Peterson olefination is an organic chemical reaction that forms an alkene from a silane and an aldehyde or ketone, in the presence of a base. This reaction is significant in the field of organic chemistry for the synthesis of alkenes. It was discovered by Donald J. Peterson in the 1960s, and since then, it has been a valuable tool for chemists in the synthesis of complex molecules.

Mechanism

The Peterson olefination mechanism involves the formation of a beta-silyl carbanion from the silane, which then reacts with an aldehyde or ketone to form a silyl ether. The silyl ether undergoes an elimination reaction, typically under acidic or basic conditions, to produce an alkene. The choice between acidic or basic conditions can influence the stereochemistry of the resulting alkene, with acidic conditions favoring the E-alkene and basic conditions favoring the Z-alkene.

Reagents and Conditions

The typical reagents for a Peterson olefination include a trialkylsilyl group attached to a carbanion, an aldehyde or ketone, and a base or acid for the elimination step. Common bases used in the reaction are strong non-nucleophilic bases such as lithium diisopropylamide (LDA) or potassium tert-butoxide (t-BuOK). The choice of reagents and conditions can be adjusted based on the desired outcome of the reaction.

Applications

Peterson olefination has been widely used in the synthesis of complex organic molecules, including natural products and pharmaceuticals. Its ability to form alkenes in a stereoselective manner makes it a valuable tool in the arsenal of synthetic organic chemists. The reaction has been applied in the synthesis of various compounds, ranging from simple alkenes to complex molecular architectures found in natural products.

Advantages and Limitations

One of the main advantages of the Peterson olefination is its stereoselectivity, allowing for the selective formation of E- or Z-alkenes. Additionally, the reaction conditions are generally mild, and the reagents are readily available. However, the reaction does have some limitations, including the potential for side reactions involving the silane reagent and the sensitivity of the reaction to moisture.

See Also

• Wittig reaction
• Julia olefination
• Tebbe reagent
• Organosilicon chemistry