Naphthosultone (Aldrich),
KOH (Fisher),
HCl, 36% (Fisher),
EtOAc (Aldrich)

1,8-naphthosultone (2.5 g 12.1 mmol) and KOH (10.1 g, 181 mmol, 15 eq) were charged into a schlenk vessel and heated to 300 ^oC for 1 h using an aluminium heating block (see note i). After cooling to RT, 100 ml of HCl/EtOAc 1:1 was added, and the solution was stirred for several hours, until all the solid material was freely moving/dissolved. A dark grey solid was removed by filtration and the solution diluted with H₂O and EtOAc and separated. The aqueous layer was washed 3x with EtOAc. The organic extracts were combined and dried over Na₂SO₄. Solvent removed in vacuo, leaving crude product as a light grey solid (2.2 g). A short silica column (2-3 cm deep, 3.5 cm diameter) (EtOAc / Pet. Ether 9:1) was employed to further purify the crude product, to give 1.1 g of off-white solid (56 %)

i) At high temperature, KOH dissolves the outer most layer of any glassware, essentially destroying it. Ideally, an inert reactor would be used, though none was available to me at the time. ii) 1,8 napthosultone begins to sublime at around 150 ^oC, but can be scraped back down the side of the reactor. As the KOH begins to melt, this becomes less of a problem. iii) After cooling, the black mixture sets hard. EtOAc and HCl are added, but depending on the depth of the vessel, this may take between several hours to several days to become free in solution. iv) Care should be taken when adding HCl to KOH. v) My yield of 56 % is less than that of the literature procedure (85 %). This may be due to insufficient heating (a previous attempt only reached 200 ^oC in a graphite bath, gave a yield of 15%).

¹H NMR (400 MHz, CDCl₃): 7.47 (2H, s, OH), 7.29 (2H, d, ³J = 7.3 Hz, ArH), 7.21 (2H, t, ³J = 7.6 Hz, ArH), 6.71 (2H, d, ³J = 7.5 Hz, ArH).

Taylor et al., J Chem Soc Perkin Trans, 1999 1073-1082