1-alkoxyvinyl esters as synthetic intermediates

Abstract

The chemistry and properties of 1-alkoxyvinyl esters and of cyclopropanones are reviewed.
A number of 1-ethoxyvinyl esters have been isolated, both for their intrinsic interest and also because of their value as synthetic intermediates.
Phthaloyl and 4-nitrophthaloyl derivatives of amino-acid esters have been prepared by reaction of phthalic acid or 4-nitrophthalic acid with ethoxyacetylene (without isolation of the correspondinc di-1-ethoxyviny: esters), in the presence of the corresponding amino-acid ester hydrochloride, Reaction of maleic acid and succinic acid with ethoxyacetylene under the same conditions, however, has yielded only the corresponding maleamic or succinamic acid.
l-Ethoxy-2-ethoxycarbonylcyclopropyl carboxylates (2-ethoxy­carbonylcyclopropanone acylals) have been prepared by the thermal deconposition of ethyl diazoacetate, catalysed by anhydrous copper sulphate, in the presence of an excess of the corresponding 1-ethoxyvinyl ester. When 1-ethoxyvinyl thiolacetate was used in this reaction, however, the product was a nitrogen containing compound, to which a pyrazoline structure has been tentatively assigned.
Experiments with 1-ethoxyvinyl esters, methylene di-iodide and zinc-copper couple yielded products which could not be successfully purified
Conversion of the 2-ethoxycarbonylcyclopropanone acylals to 2-ethoxycarbonylcyclopropanone was attempted using a variety of conditions. However, in every case, only products arising from ring cleavage reactions were obtained. An interesting boron trifluoride-catalysed rearrangnent to the corresponding acyl (or aroyl) succinic acid ester was observed.