6-(1-Ethynylbutoxy)-7,8-difluoro-2-pentylchroman → 5,6-Difluoro-3-pentyl-8-propyl-1,2,3,8-tetrahydropyrano[3,2-f]-chromene

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Reaction Steps

9.0 g (26.8 mmol) of 6-(1-ethynylbutoxy)-7,8-difluoro-2-pentylchroman are heated at 205° C. for 3 h in 90 ml of N,N-diethylaniline. The batch is diluted with MTBE and washed a number of times with 3 N HCl. The organic phase is dried using sodium sulfate and evaporated to dryness. The residue is purified by column chromatography (SiO2, n-heptane:MTBE=4:1), giving 5,6-difluoro-3-pentyl-8-propyl-1,2,3,8-tetrahydropyrano[3,2-f]-chromene as a pale-brown oil.

Provenance & Evidence