1. Prepared by : Deena Al-Fuqaha

2. Table of contents : Objectives. Background information. Reaction and mechanism. Application and recent literature. Conclusion. References.

3. Objectives :  I make this presentation to achieve the following :  To show you the mechanism for this reaction.  Give you some information about the uses of this reaction.  Show you the application and the recent literature.

4. Background information: The Corey-Seebach Reaction allows a reversal of the normal reactivity of acyl carbon atoms, which combine only with nucleophiles. The German term "Umpolung" is widely used for this inversion of reactivity.

5. Reaction mechanism: Corey-Seebach Reaction Seebach Umpolung

6. Mechanism of the Corey-Seebach Reaction The Corey-Seebach Reaction allows a reversal of the normal reactivity of acyl carbon atoms, which combine only with nucleophiles. The German term "Umpolung" is widely used for this inversion of reactivity

7. The lithiated 1,3-dithiane can be viewed as an masked acyl anion that is able to react with various electrophiles.

8. Umpolung offers access to a wide range of products, especially 1,2-diketones and α-hydroxy ketones, products that cannot be obtained using the normal reactivity (for example through aldol addtion.1,2-diketonesα-hydroxy ketones

9. 1,3-Dithianes are readily prepared from aldehydes (for an overview, see 1,3-dithianes as protecting group) and offer high stability towards acids and bases. Therefore, use of the S,S-acetal unit is especially useful in multistep synthesis. A crucial step is the hydrolysis of S,S-acetals, the difficulty of which is due to the excellent nucleophilicity of sulfur.1,3-dithianes as protecting group

10. Application and recent literature : Alkylation of 2-Lithio-1,3-dithianes with Arenesulfonates of Primary Alcohols.

11. Anion Relay Chemistry: An Effective Tactic for Diversity Oriented Synthesis

12. Trimethylene Dithioacetals of Carbohydrates, Part 6: C-C Coupling Reactions of Dilithiated N-Acetyl-D-glucosamine Trimethylene Dithioacetal Derivatives

13. Conclusion:  The lithiated 1,3-dithiane can be viewed as an masked acyl anion that is able to react with various electrophiles.

14. References:  Y.-L. Chen, R. Leguijt, H. Redlich, R. Fröhlich, Synthesis, 2006, 4212-4218  A. B. Smtih, III, M. Xiang, J. Am. Chem. Soc., 2006, 128, 66-67  D. Seebach, E.-M. Wilka, Synlett, 1976, 476- 477.

15. THE END