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A crossed aldol condensation is a result of two dissimilar carbonyl compounds containing α-hydrogen(s) undergoing aldol condensation. Ordinarily, this leads to four possible products as either carbonyl compound can act as the nucleophile and self-condensation is possible, which makes a synthetically useless mixture.
In contrast, retro-aldol condensations are rare, but possible. [14] This is the basis of the catalytic strategy of class I aldolases in nature, as well as numerous small-molecule amine catalysts. [15] When a mixture of unsymmetrical ketones are reacted, four crossed-aldol products can be anticipated: Crossed aldol (addition) reaction
Intramolecular aldol condensation is between two aldehyde groups or ketone groups in the same molecule. Five- or six-membered α , β -unsaturated ketone or aldehydes are formed as products. This reaction is an important approach to the formation of carbon-carbon bonds in organic molecules containing ring systems.
The Perkin reaction is an organic reaction developed by English chemist William Henry Perkin in 1868 that is used to make cinnamic acids.It gives an α,β-unsaturated aromatic acid or α-substituted β-aryl acrylic acid by the aldol condensation of an aromatic aldehyde and an acid anhydride, in the presence of an alkali salt of the acid.
These intermediates then react in an aldol condensation to the allyl aldehyde which the hydrogenation catalyst then reduces to the alcohol. [5] Guerbet Reaction Mechanism. The Cannizzaro reaction is a competing reaction when two aldehyde molecules react by disproportionation to form the corresponding alcohol and carboxylic acid.
In organic chemistry, the Claisen–Schmidt condensation is the reaction between an aldehyde or ketone having an α-hydrogen with an aromatic carbonyl compound lacking an α-hydrogen. It can be considered as a specific variation of the aldol condensation .
1,3-Diols are often prepared industrially by aldol condensation of ketones with formaldehyde. You can use many different starting materials to produce syn- or anti-1,3-diols. [10] The resulting carbonyl is reduced using the Cannizzaro reaction or by catalytic hydrogenation: RC(O)CH 3 + CH 2 O → RC(O)CH 2 CH 2 OH RC(O)CH 2 CH 2 OH + H 2 → ...
Mukaiyama aldol in taxol synthesis. and a second one with an amine chiral ligand and a triflate salt catalyst: Mukaiyama asymmetric aldol taxol. Utilization of chiral Lewis acid complexes and Lewis bases in asymmetric catalytic processes is the fastest-growing area in the usage of the Mukaiyama aldol reaction. [3]