Michael addition reaction

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1. TOPIC: MICHAEL ADDITION REACTION Presented By AKSHITHA D N MSc. Chemistry

2. PRESENTATION OUTLINE Introduction Michael addition reaction 1,2-addition v/s 1,4-addition Double alkylation in Michael addition Application of Michael addition reaction Conclusion

3. Introduction: Arthur Michael

4. Michael addition reaction It is the conjugate addition reaction between an ἀ , ẞ - unsaturated carbonyl compound and a compound with an active methylene group in the presence of base (ex: NaOEt or secondary amine pyridine). Reaction:

5. Michael donars : The michael reaction nucleophile is called michael acceptor. Ex: Michael acceptors : The michael reaction electrophile is called michael acceptor. Ex:

6. Reaction : Mechanism:

7. 1,2- addition v/s 1,4- addition : Strong bases are poor Michael donars . Ex- EtMgBr , LiAlH 4 ,Organolithium etc. Weak bases are good Michael donars . Ex- NaOEt * kinetic product, less stable, reversible, loses the stronger C=O ℼ- bond. * Thermodynamic product, more stable, irreversible, loses the C=C ℼ-bond, forms stable enolate.

8. Example 1:

9. Example 2: Example 3:

10. Double alkylation in Michael addition: Gilman reagent would alkylate the beta-position giving a carbonyl which selectively alkylate on the target position. Here none of the sides is less substituted to make the use of LDA or NaH beneficial for a regioselective alkylation. So, add on alkyl halide before acid work up. In this case, the intermediate enolate is still reactive and alkylation occurs on the side where the organocuprate had reacted.

11. Application of Michael reaction : Dimedone is a cyclic ketone used in organic chemistry to determine whether a compounds contains an aldehyde group. They are used as catalysts in the formation of transition metal-complexes. This Reaction is performed in three steps that involve classical carbonyl reactions, such as the Michael addition and Claisen condensation.

12. Conclusion The michael reaction is a useful method forming C-C bonds. Use of Michael addition followed by aldol condensation is an important route for the synthesis of bicylic ketone and is known as Robinson annulation. Michael addition reaction has been a very classical reaction in the field of organic synthesis, that is all kind of natural products and drugs.

13. Reference : Organic chemistry - Jonathan clayden , Nick greeves and stuart warren Organic reaction mechanisms -V.K. Ahluwalia - Rakesh kumar Parashar