Malonic esters, aryl methylene

Reaction XLIV. (b) Condensation of Alkyl and Aryl Halogen Compounds with the Sodio- and other Metallo-derivatives of Ethyl Aceto-acetate and its Homolognes. (A., 186, 214 201, 143 213, 143.)—Like malonic ester, acetoacetic ester contains two 1 3-carbonyl groups with a methylene group in position 2. It is only to be expected then that it yields with metallic sodium or sodium alcoholate sodio-derivatives from which mono- and di-, alkyl and aryl homologues can be obtained by treatment with a suitable halide, including halogen esters. Acetoacetic acid... 

CH OfiSj, H2C(S03H)2- a colourless, crystalline solid which readily absorbs water vapour decomposes on distillation. The potassium salt is prepared by heating methylene chloride with an aqueous solution of potassium sulphite under pressure at 150-I60" C. The free acid is obtained by decomposing the sparingly soluble barium salt with sulphuric acid. The aryl esters are very stable, but the alkyl esters decompose on heating to give ethers. Resembles malonic acid in some of its reactions. 

Although arylation or alkenylation of active methylene compounds can be carried out using a Cu catalyst, the reaction is sluggish. However, the arylation of malononitrile (390) or cyanoacetate proceeds smoothly in the presence of a base and Pd catalysts [189], Tetracyanoquinodimethane (392) is prepared by the coupling of / -diiodoben-zene with malononitrile (390) to give 391, followed by oxidation [190], Presence of the cyano group seems to be essential for intermolecular reactions. However, the intramolecular arylation of malonates, / -keto esters and /i-diketones proceeds smoothly [191]. The bromoxazole 393 reacts with phenylsulphonylacetonitrile (394)... 

Among common carbon-carbon bond formation reactions involving carbanionic species, the nucleophilic substitution of alkyl halides with active methylene compounds in the presence of a base, e. g., malonic and acetoacetic ester syntheses, is one of the most well documented important methods in organic synthesis. Ketone enolates and protected ones such as vinyl silyl ethers are also versatile nucleophiles for the reaction with various electrophiles including alkyl halides. On the other hand, for the reaction of aryl halides with such nucleophiles to proceed, photostimulation or addition of transition metal catalysts or promoters is usually required, unless the halides are activated by strong electron-withdrawing substituents [7]. Of the metal species, palladium has proved to be especially useful, while copper may also be used in some reactions [81. Thus, aryl halides can react with a variety of substrates having acidic C-H bonds under palladium catalysis. 

Recently a further method of alkaline nitration has been developed. It involves acetone cyanohydrin nitrate, which is readily obtained from acetone cyanohydrin and fuming nitric acid, and applies to compounds such as aryl-acetonitriles and malonic and acetoacetic esters that contain active methylene groups.130... 

Although azide reagents have been utilized in a number of chemical transformations, to date PS-TsA has only been utilized for the direct transfer of a diazo function to methylene groups flanked by either two carbonyls (eq 2), a carbonyl and an aryl sulfonyl (eq 3), or the methylene of lO/ anthracen-9-one. Diazodicarbonyl compounds such as 5-diazo-2,2-dimethyl-[l,3]dioxane-4,6-dione, 2-diazo-3-oxo-butyric acid ethyl ester, lO-diazo-lO/ anthracen-9-one, 2-diazo malonic acid diethyl ester, and 2-diazo-3-oxo-butyric acid ter/-butyl ester, as well as... 

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