Ring closure malonic acid esters

Double ring closure with malonic acid esters... 

Ring closures with malonic acid esters O... 

Table 20 Ring closures to [1,2,4]triazolo[1,5-a]pyrimidines by reaction of 3-amino[1,2,4]triazoles with /3-oxo ketones, esters, nitriles, or malonic acid derivatives...

Alkylation of malonic ester with an equimolar ponion of ethylene bromide or trimethylene bromide produces ring closure to give diethyl esters of 1,1-cyclopropane- and 1,1-cyclobutane-dicarboxylic acids, respectively. Five- and six-membered rings also have been formed in this manner. ... 

A variation on the cyclization of a-cyanomethylpyridines with a malonic ester (p. 566) is the ring closure of the acetate (104.7) with ethoxymethylene-malononitrile and of the quinolinone (104.8) with ethyl (ethoxymethylene)cya-noacetate. A methylene group in the succinic acid (104.9) readily forms an anion which attacks the electron-rich pyrrole ring on heating the compound in piperidine. COOEt... 

Pyrido[2,3-(7]pyrimidincs 23, unsubstituted in the 2,4-positions, have been synthesized by condensation of ethyl 4-aminopyrimidine-5-carboxylate with several esters, phenylacetonitrile, phenylacetamide, or malonic ester chloride.173 In the first step, the 4-amino group reacts with the ester, nitrile, or acid chloride function of the cyclization partner, ring closure then being effected by a Dieckmann-type cyclization. 

Observations on the reaction of ethylmalonatopentaamminecobalt(III) with Cr(H20)g + introduce a new element of interest. The chromium(III) products are the chelated malonate (67%) with a corresponding amount of free alcohol and the monodentate ester complex (33%). Since ester hydrolysis in the latter species is slow, we conclude that hydrogen results from the ester in the chelate form. Again, since ring closure of the monodentate product complex is slow, chelation must have occurred before Cr is oxidized to Cr . It is possible that formation of the chelate as primary product is complete, and that this product reacts in part to yield the monodentate product before hydrolysis occurs. Activation based on electron transfer to trap a function which is sensitive to a substitution-inert metal ion acting as a Lewis acid could presumably be extended to other more interesting situations. 

Ring closure with malonic acid aryl esters Resorcinol ring... 

---