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Reference EntryDOI

The Dieckmann Condensation (Including the Thorpe‐Ziegler Condensation)

15 Mar 2011-Organic Reactions (John Wiley & Sons, Inc.)-pp 1-203
TL;DR: The Dieckman condensation as mentioned in this paper is an acetoacetic ester condensation in which a dicarboxylic ester is cyclized to a beta-ketonic ester through the action of a base.
Abstract: The Dieckman condensation is an acetoacetic ester condensation in which a dicarboxylic ester is cyclized to a beta-ketonic ester through the action of a base. The dicarboxylic ester must have at least one alpha-hydrogen atom and the carbalkoxy groups must be situated that cyclization will result in a 4-membered ring or larger ring. Discovery and development of the reaction are generally credited to Dieckmann, who found that heating an adipic or a pimelic ester with sodium and a trace alcohol led to cyclization with formation of a cyclopentanone or a cyclohexanone. The Dieckmann condensation has proved useful for the preparation of a variety of carbocyclic and heterocyclic ketones and has been extended to the synthesis of 7 and 8-membered rings. Keywords: Dieckman condensation; cyclizations; Michael condensation; intermolecular ester; alkylation; acyloin condensation; failures
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Journal ArticleDOI
TL;DR: An electro-oxidative C(sp3)–H bond functionalization of acetonitrile with thiols to afford tetrasubstituted olefins with high stereoselectivity is shown and can be easily scaled up.
Abstract: Incorporation of nitrile groups into fine chemicals is of particular interest through C(sp3)-H bonds activation of alkyl nitriles in the synthetic chemistry due to the highly efficient atom economy. However, the direct α-functionalization of alkyl nitriles is usually limited to its enolate chemistry. Here we report an electro-oxidative C(sp3)-H bond functionalization of acetonitrile with aromatic/aliphatic mercaptans for the synthesis of sulfur-containing β-enaminonitrile derivatives. These tetrasubstituted olefin products are stereoselectively synthesized and the stereoselectivity is enhanced in the presence of a phosphine oxide catalyst. With iodide as a redox catalyst, activation of C(sp3)-H bond to produce cyanomethyl radicals proceeds smoothly at a decreased anodic potential, and thus highly chemoselective formation of C-S bonds and enamines is achieved. Importantly, the process is carried out at ambient temperature and can be easily scaled up.

50 citations

Journal ArticleDOI
TL;DR: Comparison of the results for cyclobutanone to those previously reported for acetone and a 1-phenylacetone derivative indicated that the ring strain of the carbocycle appeared to have only a small effect on the general base-catalyzed rate constants for enolization.
Abstract: The induction of strain in carbocycles, thereby increasing the amount of s-character in the C−H bonds and the acidity of these protons, has been probed with regard to its effect on the rate constan...

10 citations

Posted ContentDOI
29 Sep 2020-ChemRxiv
TL;DR: A simple computational approach that automatically and robustly explores chemical reaction pathways from knowledge only of the reactants and their reactive bonds is described and it is shown that these pathways can be obtained by conformational exploration with a chemically activating constraint.
Abstract: Computational power and quantum chemical methods have improved immensely since computers were first applied to the study of reactivity, but the de novo prediction of chemical reactions has remained challenging. We show that complex reactions can be efficiently and autonomously predicted using chemical activation imposed by simple geometrical constraints. Our approach is demonstrated on realistic and challenging chemistry, such as a triple cyclization cascade involved in the total synthesis of a natural product and several oxidative addition reactions of complex drug-like molecules. Notably and in contrast with traditional hand-guided computational chemistry calculations, our method requires minimal human involvement and no prior knowledge of products or mechanisms. Imposed activation can be a transformational tool to screen for chemical reactivity and mechanisms as well as to study byproduct formation and decomposition.

5 citations


Cites background from "The Dieckmann Condensation (Includi..."

  • ...In dynamical approaches, time-dependent simulations are biased to increase the probability of rare events by artificial attractive interatomic forces 5 or by performing simulations under high-energy conditions.(6,7) Alternatively, reaction paths can be generated by “walking” the potential energy surface between products and reactants, probing only necessary dimensions of the full surface....

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Journal ArticleDOI
TL;DR: The mechanism of the Wolff rearrangement of deprotonated diazocarbonyl compounds has been studied using density functional calculations, for both the gas and aqueous phases as discussed by the authors.

2 citations

01 Jan 2010

1 citations


Cites background from "The Dieckmann Condensation (Includi..."

  • ...First reported in 1887,(224) the Claisen condensation plays an important role in synthetic organic chemistry.(225-228) The Claisen condensation involves the enolate of an ester undergoing a reversible nucleophilic addition / elimination reaction with another equivalent of ester in the presence of excess base....

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