Condensation, of diethyl succinate with

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). 

Bis(trimethylsiloxy)cyclobutene, a very useful building block, is easily prepared by the modified acyloin condensation of diethyl succinate with sodium in xylene in the presence of trimethylsilylehloride 62). 

Sodium cyclopentadienide, 41, 96 Sodium dichromate for oxidation of alkylarenes to aromatic carboxylic acids, 43, 80 Sodium ethoxide for condensation of diethyl oxalate with diethyl succinate, 44, 67... 

Dicarbethoxy-l,4-cyclohexanedione has been prepared by the self-condensation of diethyl succinate by use of sodium or sodixim ethoxide catalyst (with or without a solvent) and by reaction of ethyl 4-bromo-3-ketobutanoate or ethyl 4-chloro-3-ketobutanoate with sodium ethoxide in ethanol. 

Condensation of diethyl succinate and its derivatives with carbonyl compounds in the presence of a base. 

Benzodiazocine and dibenzo[Z>,/][ 1,4]diazocine-diones (220) and (218) are obtained by condensation of diethyl succinate and phthalate, respectively, with o-phenylenediamine (69JOC2138). Contrary to an early report, the use of phthaloyl chloride leads to other products and not the tricyclic diazocine. The dibenzo derivative is also formed in the oxidation of diazabiphenylene (219) (78T495). Ring contraction of (218) occurs readily on heating or on treatment with PCI5 or with base. 

General procedure for N435-catalyzed condensation polymerization of diethyl succinate with 1,4-butanediol... 

A. Triethyl oxalylsuccinate. In a 2-1. three-necked flask equipped with a sealed stirrer and a reflux condenser bearing a calcium chloride drying tube is placed 356 ml. (276 g., 6.00 moles) of anhydrous ethanol (Note 1). Sodium (23 g., 1.0 g. atom) is added in small portions at a rate sufficient to keep the ethanol boiling. External heating is required to dissolve the last portions of the metal. After all the sodium has dissolved, the excess ethanol is removed by distillation at atmospheric pressure as the mixture becomes pasty, dry toluene is added in sufficient amounts to permit stirring and to prevent splattering of the salt. Distillation and addition of toluene is continued until all the ethanol is removed and the contents of the flask reach a temperature of 105° (Note 2). The sodium ethoxide slurry is cooled to room temperature and 650 ml. of anhydrous ether is added, followed by 146 g. (1.00 mole of diethyl oxalate. To the yellow solution there is added 174 g. (1.00 mole) of diethyl succinate, and the mixture is allowed to stand at room temperature for at least 12 hours. 

Condensation of dicyclopropyl ketone with diethyl succinate using sodium hydride as base gave... 

CH2,CH2,C02Et. From the latter the three-carbon unit of diethyl succinate may be recognised, and the Stobbe condensation is a suitable illustration of this process. Thus the reaction of aldehydes or ketones with succinic esters in the presence of potassium t-butoxide (or with sodium hydride) gives alkylidene-succinic acid esters (25). The reaction is somewhat slower in the case of the less basic sodium ethoxide. 

In condensing diethyl succinate with diethyl oxalate to form triethyl oxalyl-succinate, Bottorff and Moore " achieved a high yield with all three reactants taken in theoretical amount by the expedient of removing the ethanol prior to addition of the two esters. A solution of 23 g. of sodium in 356 ml. of ethanol was distilled at... 

Monomer Preparation. Diethyl dlacetyl succinate was prepared by the method of Knorr (8). Condensation of this compound with aromatic diamines was accomplished by the method of Helferich and Pletach (3) to give the bis(3,4 dicarboethoxy-2.5 dimethyl pyrrole) derivatives. These dlcarboethoxy pyrroles were hydrolyzed to the acids In aqueous ethanol with NaOH and converted to the dianhydrides by treatment with acetic anhydride at the reflux temperature. 

However, various attempts to prepare compound (41) by condensation of compound (40) with 3,4,5-trimethoxybenzoic acid gave poor results, although a method employing Nafion-H (ref. 51) and polyphosphoric acid ester (ref. 52) afforded compound (41) in low yield (below 30 %) accompanied with a by-product (42). Compound (42) was identified by comparison with an authentic sample, which was synthesized by the condensation of 2-methoxy-3,4-methylenedioxy-benzaldehyde and 3,4,5-trimethoxy-1 -bromobenzene followed by oxidation of the resulting benzhydrol. Moreover, the condensation of compound (4 1 ) with diethyl succinate to give compound (43) in the next step was unsuccessful. 

In the Stobbe condensation side reactions encountered by the use of other reagents are considerable—e.g., in the condensation of benzophenone and diethyl succinate with sodium ethoxide and ether, a significant amount of benzhydrol is always obtained (16). The condensation of benzophenone with diethyl succinate, using sodium hydride dispersions, was completed rapidly and gave an excellent yield (95.7%) of )3-carbethoxy-7, 7 -biphenylvinyl acetic acid. 

Table VII. Condensation of Benzophenone and Diethyl Succinate with Basic Catalysts...

Access to a 1,4-dicarbonyl substrate has been realised in several ways. Examples include alkylation of imines with 2-alkoxy-allyl halides (equivalents of 2-halo-ketones),addition of /3-ketoester anions to nitroalkenes, followed by Nef reaction,and rhodium-catalysed carbonylation of 2-substituted acrolein acetals. The dialdehyde (as a mono-acetal) necessary for a synthesis of diethyl furan-3,4-dicarboxylate was obtained by two successive Claisen condensations between diethyl succinate and ethyl formate, as shown in the sequence below. 

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]

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