Cyclopropane-1,1-dicarboxylates ring-opening reactions

Electron-withdrawing groups such as carbonyl functions render the cyclopropane ring susceptible to attack by nucleophiles. These ring-opening reactions of activated cyclopropanes by nucleophiles have been reviewed. Diethylcyclopropane-1,1-dicarboxylates la, b reacted with secondary amines such as diethylamine and piperidine to yield diethyl (2-aminoethy )malonates 2a, The nucleophilic attack of primary amines usually occurred at the ester function... 

Diethyl cyclopropane-1,1-dicarboxylate underwent a nucleophilic ring-opening reaction with disodium tetracarbonylferrate in which one of the carbon monoxide ligands acted as a C-nucleo-phile. The intermediate iron complex reacted with electrophiles such as protons or iodomethane to give y-oxopropanedioates. ... 

In anionic ring-opening polymerization of cyclopropane-1,1-dicarboxylates 22 using sodium and potassium thiophenolates as initiators, the nature of the cation was found to play an important role in the rate and selectivity of the polymerization. In particular, reaction rate increased in the order Na < C DCH18C6]... 

Ring-opening addition reactions take place between various nucleophilic reagents and a series of cyclopropanes subst. at one G-atom by 2 electron-withdrawing groups. — E A mixture of diethyl cyclopropane-1,1-dicarboxylate and 2 moles piperidine heated 20 hrs. at 102° diethyl 2-(piperidino) ethyl-malonate. Y 73%. F. e. s. J. M. Stewart and H. H. Westberg, J. Org. Ghem. 30, 1951 (1965). 

Various cyclopropanecarboxylic acids and esters have been converted to various amides, TV-alkylated amides, and hydrazides by treatment with ammonia, alkylamines, - and hydrazines, respectively. In many cases the acids have been converted via the corresponding acid chlorides generated in situ. Diethyl esters of a variety of cyclopropane-1,1-dicarboxylic acids also react with urea. Generally, all these reactions proceed smoothly and in fairly good yield and give only very small amounts of byproducts due to opening of the cyclopropane ring. 

An interesting reaction with the simultaneous opening of a cyclopropane and a cyclobutane ring was observed when sodium methoxide was added to dimethyl 2-(l-methyl-2-oxo-cyclobutyl)cyclopropane-l,l-dicarboxylate (19).The formation of the alkenes 20 by the fragmentation process occurred in high yield and stereospecificity. 

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