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The aldol reaction has one underlying mechanism: a carbanion-like nucleophile attacks a carbonyl center. [ 12 ] If the base is of only moderate strength such as hydroxide ion or an alkoxide , the aldol reaction occurs via nucleophilic attack by the resonance-stabilized enolate on the carbonyl group of another molecule.
Fig. 1: Mechanism of an intramolecular aldol reaction in basic conditions. Aldol addition product; bottom right Aldol condensation product; top right. 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 ...
An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration to give a conjugated enone. The overall reaction equation is as follows (where the Rs can be H)
The Hajos–Parrish–Eder–Sauer–Wiechert and Barbas-List [1] reactions in organic chemistry are a family of proline-catalysed asymmetric aldol reactions.. In the 1970s, two research groups discovered (and published) almost simultaneously their discoveries of two related intramolecular reactions: Zoltan Hajos and David Parrish at Hoffmann-La Roche [2] [3] and Rudolf Wiechert et al at ...
A typical reaction involving two ketones is that between acetophenone as the enol and acetone: [7] Mukaiyama aldol between two ketones. Ketone reactions of this type require higher reaction temperatures. For this work Mukaiyama was inspired by earlier work done by Georg Wittig in 1966 on crossed aldol reactions with lithiated imines.
In organic chemistry, an aldol is a structure consisting of a hydroxy group (-OH) two carbons away from either an aldehyde or a ketone. The name combines the suffix 'ol' from the alcohol and the prefix depending on the carbonyl group , either 'ald' for an aldehyde, or 'ket' for a ketone, in which case it referred to as a 'ketol'.
Glycolysis, a catabolic pathway, uses the forward reaction. Aldolase is divided into two classes by mechanism. The word aldolase also refers, more generally, to an enzyme that performs an aldol reaction (creating an aldol) or its reverse (cleaving an aldol), such as Sialic acid aldolase, which forms sialic acid. See the list of aldolases.
Robinson annulation is one notable example of a wider class of chemical transformations termed Tandem Michael-aldol reactions, that sequentially combine Michael addition and aldol reaction into a single reaction. As is the case with Robinson annulation, Michael addition usually happens first to tether the two reactants together, then aldol ...