Malonic acid, half-ester, reaction with

Reaction procedures affect the products when malonic acid half-esters (75) with an acidic hydrogen at the a-position are subjected to the modified Curtius reaction. - The usual one-pot procedure, in which alcohols are present from the beginning, affords esters (76), whereas the two-in-one procedure, in which... 

A number of new routes to a-methylene esters (121) have been developed (see also ref. 110). Perhaps the simplest involves the treatment of malonic acid half-esters with formaldehyde in pyridine containing piperidine. Yields are ca. 80%. A somewhat less efficient scheme utilizes a reaction between silyl keten acetals and chloromethyl methyl ether followed by pyrolytic removal of methanol (160 °C, KHS04). Esters (121) can also be obtained in 31—83% yield by alkylation of the Diels-Alder adduct of dimethylfulvene and methyl acrylate followed by a retro-Diels-Alder reaction. " ... 

An essentially neutral process for C-acylation relies on the reaction of imidazolides (542) with the magnesium salt (543) of a malonic acid half thiol ester (Scheme 119) (79AG(E)72>. The method requires slight modification when applied to an w-hydroxycarboxylic acid since a primary hydroxyl reacts with carbonyldiimidazole. The use of malonic acid half thiol esters in this fashion patterns the scheme proposed for carbon-carbon bond formation in the biosynthesis of fatty acids. 

Catalytic reduction of the nitrile 79 in the presence of semicarbazide affords initially the semicarbazone of 80. Hydrolysis-interchange, for example in the presence of pyruvic acid, gives the aldehyde 80. Condensation with the half ester of malonic acid leads to the acrylic ester 81 the double bond is then removed by means of catalytic reduction (82). Base catalyzed reaction of the... 

Both acid chlorides and esters are possible for dicarboxylic acids, but derivatives with only one chlorine (a half-acid chloride 145) or two chlorine atoms (a diacid dichloride, 146, actually called an acid dichloride) are possible. Similarly, a half-ester (147) or a diester (148) can be formed. In reactions of simple dicarboxylic acids such as 1,3-propanedioic acid (malonic acid, 149) with thionyl chloride, it can be difficult to generate only the half-acid chloride, 150 (malonyl chloride). Normally, the acid dichloride (151 malonyl dichloride) is formed by... 

An alternative preparation of a nitrile is illustrated by the reaction of the half-ester of 2,2-diethyl malonate 1.51) ivith SOCI2 and then NH3 to give the amide. Subsequent heating with phosphorus pentoxide led to dehydration and gave nitrile 1.52 Catalytic hydrogenation reduced the nitrile to an aminomethyl group, and acid hydrolysis gave 2,2-diethyl-3-aminopropanoic acid 1.53). 2-Ethyl-2-cyclohexyl-3-aminopropanoic acid and 2-ethyl-2-benzyl-3-aminopropanoic acid were also prepared by this method.30... 

Both aldehydes or ketones can be condensed with malonate derivatives, but ammonia can be used as a base rather than pyridine. Reaction of butanal with ammonia in the presence of the half-ester of malonic acid, for example, gave ethyl... 

The isolation of saturated and unsaturated acetic acid derivatives in the manganese(m) acetate oxidation of olefins has been reported earlier examples of this oxidation led solely to y-lactones. A one-step synthesis of aeo-di-carboxylic acid diesters has been reported, based on Kolbe electrolysis of oxalic and malonic half-esters in the presence of olefins, and is exemplified in Scheme 2. As part of a study of insect hormone activity, Kolbe electrolysis has been utilized in the preparation of aj9-unsaturated Cj4—Cj7 acid esters with a terminal quaternary alkyl group. The utility of liquid hydrogen fluoride in the Koch carbonylation of olefins has been descried, as has a general study of this reaction. ... 

Another attractive synthesis of PG s published this year starts from ( —)-5 -malic acid (67). The acid is first converted into the corresponding acid chloride (68), which by reaction with the half ester of malonic acid leads to 1,4-dione (69). Aldol cyclization of the 1,4-dione at pH 8.5 produces next the five-ring diester (70), in... 

Other alkali/alkaline earth metal iodides either cleave esters less efficiently or form insoluble carboxylate salts and are therefore not as effective as Lil. Addition of Li and l" compounds capable of forming Lil under reaction conditions works as well as initially charging Lil (Table IV). The acetaldehyde producing step. Equation 17, is carried out with the cobalt-based catalyst. Since the carboxylate half of the ester is not involved with the cobalt center, any methyl ester which can be cleaved by Lil should also show activity. We have found that methyl isobutyrate, dimethyl malonate, methyl propionate, and dimethyl succinate yield acetaldehyde and the corresponding carboxylic acids in high yield under the same conditions utilized with methyl acetate. 

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