Glycidic acid esters

Epoxides (see also a,(3-Epoxy alcohols, etc., Glycidic acids, esters, nitriles) From alkenes by epoxidation Dimethyldioxirane, 120 Fluorine-Acetonitrile, 135 Potassium peroxomonosulfate, 259 From carbonyl compounds Alumina, 14... 

Equation 15.2.2 Glycidic acid ester 3 to carboxylic acid ester 4... 

By increasing the temperature over > 300°C, the phenyl glycidic acid esters are converted to phenyl acid esters. That occurs in a consecutive decarbonylation of a-ketone carboxylic acid esters as intermediate. In the case of p-tert-butyl glycidic acid ester in the presence of a boron-pentasil zeolite at 350 °C the ratio between a-ketone carboxylic acid ester and the phenyl acetic acid ester is 65 35. 

Aromatic and aliphatic aldehydes have been prepared in good yields by the decarboxylation and isomerization of the corresponding glycidic acids. Esters of the latter are obtained by treating a ketone with ethyl chloro-acetate in the presence of sodium amide (method 127). The glycidic esters are first converted to the sodium salts with sodium ethoxide and then treated with aqueous hydrochloric acid under gentle reflux. By this procedure, a-phenylpropionaldehyde has been prepared from acetophenone in an over-all yield of 38%. Other details have been discussed. ... 

When the glycidic acid ester is to be further worked up to the phenylacetaldehyde it need not previously be distilled, but the crude ester is saponified with sodium hydroxide while steam is passed through it, and an organic acid, for instance oxalic acid, and sulphuric acid are added. Carbon dioxide is eliminated from the glycidic acid thus liberated and the phenyl-acetaldehyde distills with water. 

By analogy with the rearrangement of styrene oxide compounds, more complicated substances, e. g. phenylpyruvic acid methyl ester derivatives, can be synthesized from readily available glycidic acid esters, as shown in Figure 3. These esters can be used as intermediates for herbicides (e. g. the triazinones) and for the synthesis of L-amino acids. 

Figure 3. Rearrangement of glycidic acid esters (R = alkyl, alkoxy, halide, hydroxyl).

If the phenyl glycidic acid esters contain t-butyl- or i-propyl groups on the ester residue decarbonylation and elimination of an olefin occurs in the presence of acidic heterogeneous catalysts at temperatures > 200 °C to form phenylacetalde-hydes with high selectivity (> 80% at 100% conversion) [8]. 

Darzens-Claisen reaction Glycidic acid esters from a-halogenocarboxylic acid esters and oxo coumpounds... 

Sodium alcohol (s. a. under Cu and Ni(CO)J Darzens-Claisen reaction Synthesis of ketones from aldehydes via glycidic acid esters... 

A soln. of methoxymethyl isobutyrate in tetrahydrofuran added at -78° to 1.1 equivalents Li-diisopropylamide in the same solvent, then warmed to room temp. product. Y 69%. F. e., also prepn. of glycidic acid esters, s. A. G. Schultz and M. H. Berger, J. Org. Chem. 41, 585 (1976). 

Acylketeneacetals a- and P-Alkoxyenolesters 1-Alkoxy vinylesters 15 Enol carbonates Glycidic acid esters P-Ketocarboxylic acid esters Acylacetic esters 5... 

A soln. of /er/-butyl bromothioacetate in dichloromethane at —78° treated via syringe with 1.1 eqs. dicyclopentylborinyl triflate in the same solvent followed by 1.2 eqs. of /-Pr2NEt, stirred at —78° for 30 min, a soln. of 2,3-dimethoxybenzaldehyde in dichloromethane added slowly, stirred for a further 2 h at the same temp., 1.2 eqs. /-Pr2NEt added, the mixture warmed to room temp., and stirred for 12 h - / r/-butyl (2R, 3S )-2,3-epoxy-3-(2,3-dimethoxyphenyl)thiopropanoate. Y 62%. This method gives higher /ra 5-selectivity than the classical Darzens glycidic ester condensation. F.e. and isolation of the intermediate a-bromo-P-hydroxythiolic acid esters, also conversion to glycidic acid esters (with Mg(OMe)2) s. R.P. Polniaszek, S.E. Belmont, Synth. Commun. 19, 221-32 (1989). 

Glutaric acids by Michael addition 28,733 Glycidic acid esters... 

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