2-chloro-8-hydroxy-1,4-naphthoquinone → HCID 68456956, compound

Participants

Reaction Steps

20.1 g (58.5 mmol, 2.0 eq.) of tert-butyl 3-trimethylsilanyloxy-2-(1-trimethylsilanyloxyvinyl)but-2-enate and 5.05 g (24.3 mmol) of 2-chloro-8-hydroxy-1,4-naphthoquinone (Giles & Roos, J. Chem. Soc Perkin 11976, 2057-2060) were dissolved in 125 ml of anhydrous toluene and heated at reflux for 24 hours. The solvent was then removed on a rotary evaporator, and 150 ml of THF were added to the brown oily residue. After the addition of 10 ml of water, the mixture was stirred at RT for 1d. About 50 ml of silica gel were then added, and the mixture was freed from the solvent. The crude product, absorbed on the silica gel, was then filled into a frit filled with silica gel and eluted using DCM as mobile phase. The product band, which has an intensive yellow color and is easy to isolate, was collected separately, and, after removal of the solvent, it was possible to isolate 3.8 g (10.9 mmol, 45%) of the brown tert-butyl 3,8-dihydroxy-1-methyl-9,10-dioxo-9,10-dihydroanthracene-2-carboxylate which still contained small amounts of impurities; however, these could be removed completely in the next synthesis step.

Provenance & Evidence