Diethyl succinates, acylated

Diethyl phosphonate, 58, 134, 135, 138 Diethyl propionylsuccinate, 58, 80 82, 85 Diethyl succinate, 57, 1 Diethyl succinates, acylated, 58, 81 Diethyl sulfate, 56, 48 DIETHYL fnzHS-4-TRIMETHYLSILYL-OXY-4-CYCLOHEXENE-1,2-DICAR-BOXYLATE, 58, 163, 164, 167... 

Acylation of diethyl succinate by ethyl trifluoroacetate in presence of sodium hydride and in absence of a solvent is hazardous, fire or explosion occurring on 2 occasions some 10-20 min after adding a tittle of the succinate to the hydride-trifluoroacetate premixture at 60°C. Presence of a solvent appears to eliminate the hazard. 

B.V. The Stobbe Condensation. When succinic ester derivatives (such as diethyl succinate, 215) are condensed with non-enolizable ketones or aldehydes in the presence of base, the initial condensation product is 216. The alkoxide reacts with the distal ester via acyl substitution to give a lactone intermediate (217). In the original version of this reaction, saponification of 217 gave the a-alkylidene monoester, 218. The reaction is not completely general and is limited to those a, co-diesters for which the Dieckmann condensation is not a... 

Succinic acid esters (s. a. Acyl-succnic acid esters. Diethyl succinate)... 

Cydopentane reagents used in synthesis are usually derived from cyclopentanone (R.A. Ellison, 1973). Classically they are made by base-catalyzed intramolecular aldol or ester condensations (see also p. 55). An important example is 2-methylcydopentane-l,3-dione. It is synthesized by intramolecular acylation of diethyl propionylsucdnate dianion followed by saponification and decarboxylation. This cyclization only worked with potassium t-butoxide in boiling xylene (R. Bucourt, 1965). Faster routes to this diketone start with succinic acid or its anhydride. A Friedel-Crafts acylation with 2-acetoxy-2-butene in nitrobenzene or with pro-pionyl chloride in nitromethane leads to acylated adducts, which are deacylated in aqueous acids (V.J. Grenda, 1967 L.E. Schick, 1969). A new promising route to substituted cyclopent-2-enones makes use of intermediate 5-nitro-l,3-diones (D. Seebach, 1977). 

Friedel-Crafts acylation of benzo[6]thiophene and its derivatives with succinic anhydride132,439,662,663 or the ester chloride of succinic acid614, 618, 650,662 gives a y-keto acid (or ester), which is reduced to the corresponding y-(benzo[6]thienyl)butyric acid by the Huang Minion or Clemmensen method. y-(Benzo[6]thienyl)butyric acids may alternatively be prepared by the diethyl malonate synthesis on the appropriate halide,439,499 by the Arndt-Eistert reaction on the corresponding propionyl chloride,409,618 or by cyclization.347,618 The ketones (317 R = Hor OMe)347 have been prepared by cyclization... 

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