Synthesis of dibenzo derivatives of (4-oxotetrahydropyrano)oxa-14-crown-4 and 1,4,7-trioxacyclohexadeca-8,10,13,15-tetraen-12-one. Transformation of the latter into (4-oxopiperidino)aza-14-crown-4

The reaction of diethyl ketone with 2-{2-[2-(2-formylphenoxy)ethoxy]ethoxy} benzaldehyde in acid medium at room temperature gave 43% of dibenzo(4- oxotetrahydropyrano)oxa-14-crown-4. The condensation of the same compounds in boiling ethanol in the presence of alkali involved cascade transformations leading to the formation of thermody namically more stable dibenzocrownophane which was assigned the structure of 8,9:15,16-dibenzo-1,4,7-trioxacyclohexadec- 8,10,13,15-tetraen-12-one (yield 29%). Treatment of an alcoholic solution of the latter with gaseous ammonia or methylamine at 20°C afforded 73-74% of dibenzoaza-14-crowns-4 containing a 4-oxopiperidine fragment. © 2008 MAIK Nauka.