Ketones, reaction with succinic enolates

Syntheses from AB and AC Fragments. A considerable number of investigations has been devoted to the perfection and subsequent development of syntheses of the type AB - C described in Schemes 35-39. We must first mention work on the improvement of methods of obtaining the main starting materials, 2-aligrl-l,3-cyclo-pentanediones, both by the intramolecular acylation of y-keto acids [1073, 1074] and by the reaction of succinic anhydride with ketone enol acetates [1075] and with alkylacetic acids [1076] in the presence of AICI3. 

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). 

Vinylic and aryl halides can be used to vinylate or arylate carboxylic esters (but not ketones) by the use of NiBr2 as a catalyst.1463 However, ketones have been vinylated by treating their enol acetates with vinylic bromides in the presence of a Pd compound catalyst.1464 Also as in 0-94, this reaction can be used to close rings.1465 In one example of this, rings have been closed by treating a diion of a dialkyl succinate with a l,cu-dihalide or ditosylate,1466, e.g. ... 

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