5,6-Difluoro-8-(4-propylcyclohexyl)-1,2,3,8-tetrahydropyrano[3,2-f]chromene → 5,6-Difluoro-3-(4-propylcyclohexyl)-1,2,3,8,9,10-hexahydropyrano[3,2-f]chromene

Participants

Reaction Steps

4.0 g (11.5 mmol) of 5,6-difluoro-8-(4-propylcyclohexyl)-1,2,3,8-tetrahydropyrano[3,2-f]chromene are hydrogenated at atmospheric pressure in THF and in the presence of Pd/C (5% of Pd). The reaction solution is filtered, and the filtrate is evaporated to dryness. The residue is purified by column chromatography (SiO2, n-heptane:1-chlorobutane=1:1). The further purification is carried out by repeated recrystallisation from n-heptane at 5° C., giving 5,6-difluoro-3-(4-propylcyclohexyl)-1,2,3,8,9,10-hexahydropyrano[3,2-f]chromene as a colourless solid (m.p. 152° C.).

Provenance & Evidence