Stobbe

The condensation of aldehydes and ketones with succinic esters in the presence of sodium ethoxide is known as the Stobbe condensation. The reaction with sodium ethoxide is comparatively slow and a httlo reduction of the ketonic compound to the carbinol usually occurs a shorter reaction time and a better yield is generally obtained with the more powerful condensing agent potassium ieri.-butoxide or with sodium hydride. Thus benzophenone condenses with diethyl succinate in the presence of potassium [Pg.919]

The Stobbe condensation thus provides a method for introducing a propionic acid residue at the site of a carbonyl group. 

Stephen reaction Stobbe condensation UUmann reaction Willgerodt reaction. ... 

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). 

Succinic esters condense with aldehydes and ketones in the presence of bases, eg, sodium alkoxide or piperidine, to form monoesters of alkybdenesuccinic acids, eg, condensation of diethyl succinate with acetone yields ethyl 2-isopropyhdenesuccinate (eq. 3). This reaction, known as Stobbe condensation, is specific for succinic esters and substituted succinic esters (98,99). 

Aromatic aldehydes (100), eg, cinnamaldehyde, and ketones (101) react ia a similar manner (eq. 4). Ketones containing reactive methyl or methylene groups give with succiaates, ia the presence of sodium hydride, both the Stobbe condensation and the formation of diketones by a Claisen mechanism (102) (eq. 5). 

KNOEVENAGEL OOEBNER STOBBE Condensation Base catalyzed aldol condensation of aldehydes or ketones with an activated methylene group of a malonic ester (Knoevenagel Doebner) or a succinic ester (Stobbe)... 

The. synthesis starts with the Stobbe condensation of diethylsuccinate and 3,4-dichloroben-zophenone (13). The product (14) is hydrolyzed and decarboxylated to a cis-trans mixture of olefins (15). This last is reduced using a Pd/C catalyst and then undergoes unidirectional Friedel-Crafts intramolecular acylation into the more reactive ring to produce substituted tetralone 16. 

An intriguing rearrangement was reported by Yates (72) during an attempt to carry out the Stobbe condensation. It resulted in the formation of a cyclopropane derivative from 4-benzoyloxycyclohexanone by the (proposed) mechanism shown. 

Once such effects had been noted, it became necessary to interpret the observed results and to classify the solvents. The earliest attempts at this were by Stobbe, who reviewed the effects of solvents on keto-enol tautomers [4]. Since then many attempts have been used to explain solvent effects, some based on observations of chemical reactions, others on physical properties of the solvents, and yet others on spectroscopic probes. All of these have their advantages and disadvantages and no one approach can be thought of as exclusively right . This review is organized by type of measurement, and the available information is then summarized at the end. 

Y.Zheng, W.M.Stobbs, The tweed microstructure in B2 Ni-rich Ni-Al alloys, in Electron Microscopy and Analysis 95, ed. D.Chems, Inst Phys.Conf Ser. No 147, Inst.of Physics (1995), p.353... 

The Stobbe condensation has been extended to di-rert-butyl esters of glutaric... 

Sandercock P, Counsell C, Stobbs SL. Low-molecular-weight heparins or Heparinoids versus standard Unfractionated heparin for acute ischemic stroke (Review). The Cochrane Collaboration 2006. 

Table 6 Stobbe condensation reaction of 22 and 23 in the solid state...

In 1910 Stobbe and Posnjak drew the conclusion that polystyrene is a colloidal body after noting that boiling point elevations of its solutions are negligible. They proposed cyclic formulas composed of four, five, or possibly more structural units, e.g. 

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