Ethyl ester, tetraacetate

It has been shown that the lead tetraacetate-mediated 1,2-aryl shift of various meta-substituted / -cyclohexyl aryl ketones, e.g. (10), results in excellent yields of the corresponding rearranged esters (11). A unique reaction, providing 3-hydroxy-2-arylacrylic acid ethyl esters (14), has been observed between aryl aldehydes and ethyl diazoacetate in the presence of the iron Lewis acid [rj — (C5H5)Fe(CO)2(THF)BF4], It appears that the enol esters are formed by an unusual 1,2-aryl shift from a possible intermediate (13), which in turn is formed from the reaction of the iron aldehyde complex (12) with ethyl diazoacetate (see Scheme 4). 

Gardiner [84,85] described a gas chromatographic method for the determination of EDTA in aqueous environmental samples. The separation of the major peaks is increased by preparing the ethyl derivatives of the sample compounds, 1,6-hexanediamine tetraacetic acid (HDTA) being used as internal standard. The lower limit of detection of the method is approximately 15pg L 1 with 25mL samples. In this method the ethyl derivatives of the sample components were prepared so that the major peaks would be well separated. The ethyl esters of fatty acids up to and including the Qg fatty acids eluted well before the EDTA derivatives and did not interfere. 

The hydrogenolysis of the thiol esters of carboxylic acids offers a delicate method for reducing an acid to the corresponding aldehyde or alcohol application of this method to the sugar series has been made by Wolfrom and Karabinos who reduced D-ribonyl chloride tetraacetate (LXXV) to aldehydo-D-ribose tetraacetate (LXXVII) in 22% yield via ethyl thiol-D-ribonate tetraacetate (LXXVI). The desulfurization of the thiol ester (LXXVI) was carried out with a somewhat aged sample of Raney nickel" which doubtless had less activity than the... 

Galacturonic acid, aldehydo-D-, tetraacetate methyl ester ethyl hemiacetal, 25... 

Independently, the groups of Evans [375,376,377] and J0rgensen [378] have shown that /3,y-unsaturated a-keto esters react with ethyl vinyl ether in the presence of enantiomerically pure bisoxazoline copper(II) complexes as catalysts leading to enantiomerically enriched dihydropyrans. For instance 212 and 213 in ether at 20 °C and in the presence of complex 214 add to give the endo adduct 215 in 60% yield and with 96.5% ee. The latter is then converted into ethyl -D-ma no-p)Tanoside tetraacetate 216 (O Scheme 77) [379]. 

Ludwig. This compound has an empirical formula corresponding to structure (1) and shows the ultraviolet and infrared" absorptions of a pyrrole-3-carboxylic ester. Its acetylation gives a tetra-O-acetyl derivative." Oxidation with lead tetraacetate yields ethyl 5-formyl-2-methyl-pyrrole-3-carboxylate (4), identical with the compound prepared in a different way. Oxidation with potassium permanganate in alkaline solution at low temperature yields 3-(ethoxycarbonyl)-2-methylpyrrole-5-carboxylic acid (7) which can be transformed " into the diethyl ester (8), identical... 

The reaction, under the same conditions, has been extended to other /3-keto esters. Ethyl 3-oxovalerate, ethyl 3-oxohexanoate, and diethyl 3-oxoglutarate react with 2-amino-2-deoxy-D-glucose to give compounds (11), (12), and (13), respectively, whose oxidations with lead tetraacetate or periodic acid furnish the corresponding aldehydes (14), (IS), and (16). 

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