CoreyâSeebach reaction | |
---|---|
Named after |
Elias James Corey Dieter Seebach |
Reaction type | Coupling reaction |
Identifiers | |
Organic Chemistry Portal | corey-seebach-reaction |
The CoreyâSeebach reaction, or Seebach Umpolung is a name reaction of organic chemistry that allows for acylation by converting aldehydes into lithiated 1,3-dithianes. The lithiated 1,3-dithianes serves as an acyl anion equivalent, undergoing alkylation with electrophiles. [1] The reaction is named in honor of its discoverers, Elias J. Corey and Dieter Seebach.
The aldehyde is first converted into a dithiane, usually with 1,3-propanedithiol. The resulting 1,3-dithiane is then lithiated with the use of butyllithium. The 2-lithio-1,3-dithiane reacts with electrophiles to give a 2-alkyl-1,3-dithiane.
Finally, the 2-alkyl-1,3-dithiane can be converted to a carbonyl by hydrolysis, usually with the use of mercury(II) oxide. Alternatively the 2-alkyl-1,3-dithiane can be reduced to an alkane. [2]
As a strategy for protecting aldehydes and ketones, dithiane formation is cumbersome because deprotection is inefficient. Typically ketones and aldehydes are protected as their dioxolanes instead of dithianes. The Corey-Seebach reaction is of interest as an acyl anion equivalent, allowing aldehydes to be converted to ketones.
The lithiated 1,3-dithiane can be alkylated with alkyl halides, epoxides, [3] [4] ketones, acyl halides, and iminium salts, which after hydrolysis of dithioacetals can yield ketones, ÎČ-hydroxyketones, α-hydroxyketones, 1,2-diketones [5] and α-aminoketones. Notably, α-hydroxyketones and 1,2-diketones can not be generated through typical reactions of aldehydes such as the aldol reaction. [6] Other possible electrophiles include aldehydes, [7] amides, and esters. [6] [8]
The reaction between lithiated 1,3-dithianes and arenesulfonates offers a similar path to that of alkyl halides, being able to form dithioacetals which can be converted to ketones. [9]
CoreyâSeebach reaction | |
---|---|
Named after |
Elias James Corey Dieter Seebach |
Reaction type | Coupling reaction |
Identifiers | |
Organic Chemistry Portal | corey-seebach-reaction |
The CoreyâSeebach reaction, or Seebach Umpolung is a name reaction of organic chemistry that allows for acylation by converting aldehydes into lithiated 1,3-dithianes. The lithiated 1,3-dithianes serves as an acyl anion equivalent, undergoing alkylation with electrophiles. [1] The reaction is named in honor of its discoverers, Elias J. Corey and Dieter Seebach.
The aldehyde is first converted into a dithiane, usually with 1,3-propanedithiol. The resulting 1,3-dithiane is then lithiated with the use of butyllithium. The 2-lithio-1,3-dithiane reacts with electrophiles to give a 2-alkyl-1,3-dithiane.
Finally, the 2-alkyl-1,3-dithiane can be converted to a carbonyl by hydrolysis, usually with the use of mercury(II) oxide. Alternatively the 2-alkyl-1,3-dithiane can be reduced to an alkane. [2]
As a strategy for protecting aldehydes and ketones, dithiane formation is cumbersome because deprotection is inefficient. Typically ketones and aldehydes are protected as their dioxolanes instead of dithianes. The Corey-Seebach reaction is of interest as an acyl anion equivalent, allowing aldehydes to be converted to ketones.
The lithiated 1,3-dithiane can be alkylated with alkyl halides, epoxides, [3] [4] ketones, acyl halides, and iminium salts, which after hydrolysis of dithioacetals can yield ketones, ÎČ-hydroxyketones, α-hydroxyketones, 1,2-diketones [5] and α-aminoketones. Notably, α-hydroxyketones and 1,2-diketones can not be generated through typical reactions of aldehydes such as the aldol reaction. [6] Other possible electrophiles include aldehydes, [7] amides, and esters. [6] [8]
The reaction between lithiated 1,3-dithianes and arenesulfonates offers a similar path to that of alkyl halides, being able to form dithioacetals which can be converted to ketones. [9]