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The Dieckmann condensation, where a molecule with two ester groups reacts intramolecularly, forming a cyclic β-keto ester. In this case, the ring formed must not be strained, usually a 5- or 6-membered chain or ring. Retro-Claisen condensation is the reverse of the title reaction, i.e., the base-induced cleavage of 2-ketoesters
It can be considered as a specific variation of the aldol condensation. This reaction is named after two of its pioneering investigators Rainer Ludwig Claisen and J. Gustav Schmidt, who independently published on this topic in 1880 and 1881. [1] [2] [3] An example is the synthesis of dibenzylideneacetone ((1E, 4E)-1,5-diphenylpenta-1,4-dien-3 ...
The Claisen rearrangement is a powerful carbon–carbon bond-forming chemical reaction discovered by Rainer Ludwig Claisen. [1] The heating of an allyl vinyl ether will initiate a [3,3]-sigmatropic rearrangement to give a γ,δ-unsaturated carbonyl, driven by exergonically favored carbonyl CO bond formation with Δ(Δ f H) ca. −25 kcal/mol (−100 kJ/mol).
Many variations of condensation reactions exist. Common examples include the aldol condensation and the Knoevenagel condensation, which both form water as a by-product, as well as the Claisen condensation and the Dieckman condensation (intramolecular Claisen condensation), which form alcohols as by-products. [5]
The ACP-bound elongation group reacts in a Claisen condensation with the KS-bound polyketide chain under CO 2 evolution, leaving a free KS domain and an ACP-bound elongated polyketide chain. The reaction takes place at the KS n -bound end of the chain, so that the chain moves out one position and the elongation group becomes the new bound group.
For example, thin mucus may be a sign of an early infection, but as the mucus thickens, this suggests more severe congestion in the nose, experts say. What does green mucus mean?
Social Security has two other funding sources: benefit taxes on some seniors and interest income earned on money in the program's trust funds. But both of those are in danger right now. The ...
Darzens condensation, Darzens–Claisen reaction, Glycidic ester condensation; Darzens halogenation; Darzens synthesis of unsaturated ketones; Darzens tetralin synthesis; Davis' reagent, Davis oxidation; Davis–Beirut reaction; De Kimpe aziridine synthesis; Dehydration reaction; Dehydrogenation; Delépine reaction; DeMayo reaction; Demjanov ...