Michael addition

The Michael Addition is a nucleophilic addition reaction involving the addition of a carbanion or another nucleophile to an α,β-unsaturated carbonyl compound, resulting in the formation of a carbon-carbon bond. This reaction is a subset of conjugate addition reactions and is widely used in organic synthesis due to its ability to form carbon-carbon bonds in a mild and efficient manner[1][4][8][10][11].

Mechanism

The mechanism of the Michael Addition typically involves three key steps:

1. Deprotonation: A base deprotonates the Michael donor, which is often a compound with an active methylene group, such as malonates or nitroalkanes, to generate a carbanion[1][4][12].
2. Conjugate Addition: The carbanion then performs a 1,4-addition to the α,β-unsaturated carbonyl compound, also known as the Michael acceptor[1][4][12].
3. Protonation: Finally, the resulting enolate is protonated to give the Michael adduct, which is a 1,5-dicarbonyl compound when the donor is a 1,3-dicarbonyl compound[1][4][12].

Reaction Conditions

The reaction typically requires a strong base to generate the carbanion and may require elevated temperatures depending on the substrates involved. The choice of solvent and base can be crucial for the success of the reaction[1][4][12].

Applications

The Michael Addition is used extensively in the synthesis of natural products, drugs, and complex compounds with biological activities. It is an important tool in the construction of carbon skeletons in organic synthesis and is also used in green chemistry due to its atom-economical and environmentally friendly nature[3][7][11]. The reaction can be used to create a wide variety of compounds, including those with biological and medicinal importance[3][7][11].

Variants of the Michael Addition include the Aza-Michael addition, involving a nitrogen nucleophile, and the Oxa-Michael addition, involving an oxygen nucleophile[2]. The reaction is also used in post-translational modification of proteins, where it involves covalent additions to amino acid side chains[9][13].

In summary, the Michael Addition is a versatile and widely applied reaction in organic chemistry, enabling the formation of complex molecules through the creation of carbon-carbon bonds under relatively mild conditions.

Citations:

[1] https://www.masterorganicchemistry.com/2023/05/24/michael-addition-reaction-conjugate-addition/

[2] https://commonorganicchemistry.com/Rxn_Pages/Michael_Addition/Michael_Addition_Index.htm

[3] https://www.eurekaselect.com/article/79844

[4] https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Organic_Chemistry_(Morsch_et_al.)/23:_Carbonyl_Condensation_Reactions/23.10:_Conjugate_Carbonyl_Additions_-_The_Michael_Reaction

[5] https://www.sciencedirect.com/science/article/pii/S0300944097000702

[6] https://youtube.com/watch?v=dEdsR-6dKWE

[7] https://www.ingentaconnect.com/content/ben/cos/2017/00000014/00000004/art00007

[8] https://en.wikipedia.org/wiki/Michael_addition_reaction

[9] https://www.researchgate.net/publication/317754736_Applications_of_Michael_Addition_Reaction_in_Organic_Synthesis

[10] https://www.organic-chemistry.org/namedreactions/michael-addition.shtm

[11] https://www.chemistrylearner.com/michael-addition.html

[12] https://www.chemistrysteps.com/michael-reaction-conjugate-addition-enolates/

[13] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8473112/

[14] https://byjus.com/chemistry/michael-addition-mechanism/

[15] https://www.sciencedirect.com/science/article/abs/pii/S0300944097000702

[16] https://youtube.com/watch?v=CBLx2vchUiA