Malonic isopropylidene ester

Meldrum s acid Malonic acid, cyclic isopropylidene ester (8) 1,3-Dioxane-4,6-dione, 2,2-dimethyl- (9) (2033-24-1)... 

Thermal cyclization of the isopropylidene ester of the malonates (70) was accompanied by decarboxylation at position 3, whereby 4-oxo-4H-pyrido-[l,2-fl]pyrimidines (74 R1 = H) were obtained.79,142,143 When the cyclization was performed in phosphoryl chloride-polyphosphoric acid and the reaction mixture was treated with alcohol, 4-oxo-4H-pyrido[l,2-a]pyri-midine-3-carboxylic acid esters were isolated.151 Treatment of the reaction mixture with water gave carboxylic acids. 

Dimethyl-1,3-Dioxane-4,6-dione (Meldrum s Acid) Malonic acid, cyclic isopropylidene ester (8) 1,3-Dioxane-4,6-dione, 2,2-dimethyl- (9) (2033-24-1) Ethylenediammonium diacetate 1,2-Ethanediamine diacetate (9) (38734-69-9) (R)-Citronellal 6-Octenal, 3,7-dimethyl-, (R)-(+)- (8,9) (2385-77-5)... 

MELDRUM S ACID 2,2-DIMETHYL-1,3-DIOXANE-4,6-DIONE MALONIC ACID, CYCLIC ISOPROPYLIDENE ESTER 1,3-DIOXANE-4,6-DIONE, 2,2-DIMETHYL- (2033-24-1), 67, 170 69, 33 p-Mentha-6,8-dien-2-one (6485-40-1), 66, 13... 

The reaction is equally successful when isopropylidene malonate is used in place of malonic acid or diethyl malonate.913 The isopropylidene ester contains an unusually acidic methylene group as well as an ester group that can be... 

Meldrum s acid Malonic acid, cyclic isopropylidene ester (8) ... 

These model reactions were of great value in the extension of the C-glycosylation reaction with malonic esters to five-membered ring-systems. Treatment of 2,3 5,6-di-O-isopropylidene-a-D-manno-furanosyl bromide122,123 (150) with diethyl sodiomalonate led to an anomeric mixture of C-glycosyl compounds that could be separated by column chromatography, with the a (151) and /B (152) anomers in... 

Dhimane et al. studied the flash vacuum pyrolysis of isopropylidene [l-(a>-chloroalkyl)-l-azacycloalk-2-ylidene]malonates (1274) at 570°C and 1CT4 torr (87TL885 89T6161) (Scheme 52). They obtained bicyclic esters (1276) in 35-45% yields when the pyrolytic products were condensed on a cold finger at -196°C, covered with methanol, and triethylamine was introduced at the end of the reaction. Pyrolysis of the pyrrrolidine derivative (1274, n = 0, m = 1) without methanol on the cold finger afforded the bicyclic carboxylic chloride (1275, n = 0, m = 1), which was converted to ester (1276, n - 0, m = 1) by treatment with a mixture of methanol and triethylamine. 

Isopropylidene (l-aminoalkylidene)malonates (454) were heated under reflux in ethanol in the presence of sodium ethylate overnight. After evaporation of the solvent, the residues were treated with water to give 3-aminoacrylates (1608) in 48-89% yields. If the residues were treated with water and 10% hydrochloric acid, 3-oxo esters (1609) were obtained in 22-81% yields. When isopropylidene (l-aminoalkylidene)malonates (454) were heated under reflux in concentrated hydrochloric acid, methylke-tones (1610) were prepared in 24-73% yields (81S130). 

The treatment of isopropylidene (2-azacycloalkylidene)malonates (468, R4 = H) with sodium ethylate in boiling ethanol for 12 hr or overnight gave the amino ester (1623) in 58-91% yields (79JOC3089 88FRP2607497). Acidic and nonacidic alcoholysis was ineffective (79JOC3089). 

A methanolic solution of isopropylidene (3-methyl-6-oxopiperidin-2-yli-dene)malonate (537) was boiled overnight in the presence of sodium methylate to give monomethyl malonate (1627) in 86% yield (86JST319). The half ester (1627) was decarboxylated at 150°C to afford methyl (3-methyl-6-oxopiperidin-2-ylidene)acetate (1628) in 95% yield. 

Ethanolic solutions of isopropylidene (azacycloalk-2-ylidene)malonates (1629) were boiled in the presence of sodium ethylate overnight to give ethyl (azacycloalk-2-ylidene)acetates (1630, XR = OEt) in 56-90% yields (83S195). Acrylates (1630, X = O) or acryl amides (1630, X = NEt) were also prepared when mixtures of cyclic esters (1629) and the respective alcohol or amine were heated for 30 min at a temperature 25°C higher than the decomposition point. The latter was sometimes carried out in acetone. 

Hence, Stobbe-like condensation with dimethyl-isopropylidene malonate and saponification of malonic acid, half-esters afforded the corresponding 14-carboxyretinoic acids, as a mixture of all E and 9Z isomers (80/20). The all E diacid was easily removed by crystallization from MeCN or ether, Fig. (36). A stereospecific decarboxylation in 2,6-dimethylpyridine led to isotretinoin. 

In parallel fashion, compound 267, made from 2,3 5,6-di-<9-isopropyl-idene-D-mannono-1,4-lactone by Reformatsky addition using ethyl bromo-acetate and zinc-silver graphite, undergoes ready elimination when converted to the methanesulfonic ester to give a separable mixture of the E- and Z-alkenes (268).251 Quite a different approach involves treatment of the 1-C-nitromannofuranosyl chloride, derived from the oxime of 2,3 5,6-di-O-isopropylidene-D-mannose, with the anion of diethyl malonate to give the disubstituted alkene 269.252... 

Corey found the reagent useful for the synthesis of half-esters of a,/3-unsaturated malonic esters. Isopropylidene malonate condenses readily with carbonyl compounds, even with the highly hindered mesitaldehyde (1). Thus the condensation of (I) and (2) was conducted in pyridine solution, and the product (3) on being refluxed with absolute ethanol and a trace of hydrogen chloride afforded ethyl hydrogen mesitylidene malonate (4). 

Carboxylic acids add to olefinic linkages under acid catalysis to form esters and the method has been employed to prepare tetrahydropyranyl (reagent dihydropyran) [52] and t-butyl (reagent wo-butene) [53, 54, 55] esters. The little used isopropylidene malonate (15) is similarly produced from iso-propenyl acetate and malonic acid in the presence of sulphuric acid [56, 57]. 

Dicarboxylic acids, such as malonic acid, have been infrequently used in the form of protected cyclic isopropylidene or benzylidene derivatives, e.g. (15) and (22). The esters are saponified by base and as befits their acetal structures by acids also [56, 57, 67, 126]. Presumably the benzylidene ester may be cleaved by hydrogenolysis. Rather more use has been made of cyclic protecting groups in the case of a-hydroxyacids. Lemieux [68] thus used the ready formation of a neutral... 

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