Dieckmann

Oschkinat H, Muller T and Dieckmann T 1994 Protein structure determination with three- and four-dimensional spectroscopy Angew. Chem. Int. Ed. Engl. 33 277-93... 

Wall M R, Dieckmann T, Feigon J and Neuhauser D 1998 Two-dimensional filter-diagonalization spectral inversion of 2D NMR time-correlation signals including degeneracies Chem. Phys. Lett. 291 465... 

Esters of dicarboxyUc acids having hydrogen on tbe 8 or e carbon atoms undergo intramolecular cyclisation when heated with sodium or with sodium ethoxide. This cyclisation is known as the Dieckmann reaction. It is essentially an application of the Claiseu (or acetoacetic eater) condensation to the formation of a ring system the condensation occurs internally to produce s... 

Benzilic acid rearrangement Benzoin reaction (condensation) Blanc chloromethylation reaction Bouveault-Blanc reduction Bucherer hydantoin synthesis Bucherer reaction Cannizzaro reaction Claisen aldoi condensation Claisen condensation Claisen-Schmidt reaction. Clemmensen reduction Darzens glycidic ester condensation Diazoamino-aminoazo rearrangement Dieckmann reaction Diels-Alder reaction Doebner reaction Erlenmeyer azlactone synthesis Fischer indole synthesis Fischer-Speior esterification Friedel-Crafts reaction... 

Synthesis This cyclisation version of the Claisen ester condensation is sometimes called the Dieckmann Reaction. 

We begin with the discussion of intramolecular reactions. An example of a regioselec-tive Dieckmann condensation (J.P. Schaefer, 1967) used an educt with two ester groups, of which only one could form an enolate. Regioselectivity was dictated by the structure of the educt. 

Knoevenagel, Dieckmann, Stobbe, and Reformatsky reactions to name just a few. 

A classical way to achieve regioselectivity in an (a -i- d -reaction is to start with a-carbanions of carboxylic acid derivatives and electrophilic ketones. Most successful are condensations with 1,3-dicarbonyl carbanions, e.g. with malonic acid derivatives, since they can be produced at low pH, where ketones do not enolize. Succinic acid derivatives can also be de-protonated and added to ketones (Stobbe condensation). In the first example given below a Dieckmann condensation on a nitrile follows a Stobbe condensation, and selectivity is dictated by the tricyclic educt neither the nitrile group nor the ketone is enolizable (W.S. Johnson, 1945, 1947). 

Some straightforward, efficient cyclopentanellation procedures were developed recently. Addition of a malonic ester anion to a cyclopropane-1,1-dicarboxylic ester followed by a Dieckmann condensation (S. Danishefsky, 1974) or addition of iJ-ketoester anions to a (l-phenylthiocyclopropyl)phosphonium cation followed by intramolecular Wittig reaction (J.P, Marino. 1975) produced cyclopentanones. Another procedure starts with a (2 + 21-cycloaddition of dichloroketene to alkenes followed by regioselective ring expansion with diazomethane. The resulting 2,2-dichlorocyclopentanones can be converted to a large variety of cyclopentane derivatives (A.E. Greene. 1979 J.-P. Deprds, 1980). 

Walter Dieckmann was a German chemist and a contemporary of Claisen... 

This reaction is an example of a Dieckmann cyclization The anion formed by proton abstraction at the carbon a to one carbonyl group attacks the other carbonyl to form a five membered ring... 

Write the structure of the Dieckmann cyclization product formed... 

The carbon-carbon bond forming potential inherent m the Claisen and Dieckmann reac tions has been extensively exploited m organic synthesis Subsequent transformations of the p keto ester products permit the synthesis of other functional groups One of these transformations converts p keto esters to ketones it is based on the fact that p keto acids (not esters ) undergo decarboxylation readily (Section 19 17) Indeed p keto acids and their corresponding carboxylate anions as well lose carbon dioxide so easily that they tend to decarboxylate under the conditions of their formation... 

The starting material in this example is the Dieckmann cyclization product of diethyl heptanedioate (see Problem 21 2a)... 

Dieckmann cyclization (Section 21 2) An intra molecular analog of the Claisen condensation Cy die p keto esters in which the ring is five to seven membered may be formed by using this reaction... 

Dieckmann reaction (Section 21 2) An intramolecular version of the Claisen condensation... 

Potassium Amides. The strong, extremely soluble, stable, and nonnucleophilic potassium amide base (42), potassium hexamethyldisilazane [40949-94-8] (KHMDS), KN [Si(CH2]2, pX = 28, has been developed and commercialized. KHMDS, ideal for regio/stereospecific deprotonation and enolization reactions for less acidic compounds, is available in both THF and toluene solutions. It has demonstrated benefits for reactions involving kinetic enolates (43), alkylation and acylation (44), Wittig reaction (45), epoxidation (46), Ireland-Claison rearrangement (47,48), isomerization (49,50), Darzen reaction (51), Dieckmann condensation (52), cyclization (53), chain and ring expansion (54,55), and elimination (56). 

D. Dieckmann in Modem Plastics Enyclopedia 92, McGraw-Hill Book Co., Inc., 1991, pp. 184—187. 

The other main reaction in this class is the Dieckmann-type cyclization of the intermediates (163) from 4(6)-halo-5-ethoxycarbonylpyrimidines with AC-substituted /3-alanine esters and nitriles, and related compounds, to give 5,6,7,8-tetrahydro-5-oxopyrido[2,3-[Pg.221]

The only example from a pyridazine intermediate is of the Dieckmann-type used so widely in the pyridopyrimidine field (Section 2.15.5.4.2). The 3-carboxyalkylamino-4-ester (365) is cyclized by strong base to give the pyrido[2,3-c]pyridazine-6-carboxylate (366) (77JAP(K)7733695). 

The first example of this type also mimics a synthesis used in the pyridopyrimidine field, in which the quinoxaline diester (427) is cyclized in Dieckmann fashion to the pyri4o[2,3-]quinoxaline (428) (76CR(C)(282)861). 

Dicoumarol — see Coumarin, 3,3 -methylenebis(4-hydroxy-Dictamnine biosynthesis, 4, 992 occurrence, 4, 989 pharmacology, 4, 992 synthesis, 4, 990 Dicyanocobyrinic acid heptamethyl ester, 4, 422 Dicycloalkaselenophenes synthesis, 4, 968 Dicyclohexa-1,4-diselenins thermolysis, 4, 968 Dieckmann condensation chroman-3-one synthesis by, 3, 854 isochroman-4-one synthesis by, 3, 859 oxoindolizidine synthesis by, 4, 471... 

Dieckmann reaction, 4, 471 Indolizidine alkaloids mass spectra, 4, 444 Indolizidine immonium salts reactions, 4, 462 Indolizi dines basicity, 4, 461 circular dichroism, 4, 450 dipole moments, 4, 450 IR spectra, 4, 449 reactivity, 4, 461 reviews, 4, 444 stereochemistry, 4, 444 synthesis, 4, 471-476 Indolizine, 1-acetoxy-synthesis, 4, 466 Indolizine, 8-acetoxy-hydrolysis, 4, 452 synthesis, 4, 466 Indolizine, I-acetyl-2-methyI-iodination, 4, 457 Indolizine, 3-acyloxy-cyclazine synthesis from, 4, 460 Indolizine, alkyl-UV spectra, 4, 449 Indolizine, amino-instability, 4, 455 synthesis, 4, 121 tautomerism, 4, 200, 452 Indolizine, 1-amino-tautomerism, 4, 38 Indolizine, 3-amino-synthesis, 4, 461, 470... 

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