77420-29-2Relevant articles and documents
Synthesis of 7,8,9,10,11,12,20,21,22,23,24,25-Dodecahydrodibenzotetraoxacyclodocosin, a Crown Ether
Tyman, John H. P.,Grundy, Jesse,Brown, George R.
, p. 336 - 343 (2007/10/02)
A number of symmetrical diesters and an unsymmetrical type have been synthesised from pyrocatechol.Under conditions in which intramolecular acyloin formation was anticipated the product from one symmetrical compound, ethyl 4-(o-ethoxycarbonylpropoxyphenoxy)butyrate, was a cyclic bis-β-keto-ester resulting in reasonable yield from intermolecular Dieckmann cyclisation.Hydrolysis to the 9,22 diketone, and its reduction to 7,8,9,10,11,12,20,21,22,23,24,25-dodecahydrodibenzotetraoxacyclodocosin 'dibenzo-22-crown-4', proceeded smoothly.An unsymmetrical intermediate, methyl 4-(o-ethoxycarbonylmethoxypropylphenoxy)butyrate, was prepared for similar cyclisation and in preliminary experiments appeared to give acyloin and β-keto-ester products.The method represents a different approach to crown ether systems of certain types.
