Thioxanthen-9-one (Prepared in house, see Synthetic Page 847)
Sodium borohydride (Sigma Aldrich)
Isopropyl alcohol (IPA) (Fisher Scientific)
Tetrahydrofuran (THF) (Fisher Scientific)

A mixture of thioxanthen-9-one (1 g, 4.7 mmol), isopropyl alcohol* (40 mL) and THF (20 mL) was heated to reflux with constant stirring**. Upon a clear solution being obtained***, NaBH₄ (1.4 g, 18.5 mmol) was added in small portions carefully, and the reaction was left to stir at reflux for 3 hours. Upon cooling, the solution poured over ice (250 g) and the reaction mixture was stirred at speed until a white solid was produced****. The solid was isolated and dried at the pump under vacuum filtration***** to yield thioxanthen-9-ol (0.77 g, 76%) as a white solid.

* IPA used instead of methanol due to solubility issues with the starting thioxanthen-9-one.
** Round bottom flask fitted with a reflux condenser was used which fitted snuggly into a metal heating block.  A thermocouple was used to control the temperature and reaction was open to the air (no inert gasses were required).  Stirring accomplished using a stirring bar which was controlled from the hot plate.  
*** A clear solution obtained after 10 minutes at reflux, however should this not happen add 5 mL portions of THF (slowly) to the reaction mixture (through the top of the condenser) until a clear solution is obtained.
**** Should only a small amount of white solid be produced upon stirring, the addition of distilled water (approx.. 200mL) in one potion will help precipitation.
*****No purification required, but the authors suggest holding the compound at the vacuum pump until dry.  The authors suggest doing this for one hour.  

¹H NMR (400 MHz, DMSO-d6) δ 7.70 (d, J = 7.7 Hz, 2H), 7.51 (d, J = 7.6 Hz, 2H), 7.41 – 7.34 (m, 2H), 7.31 – 7.24 (m, 2H), 6.45 (d, J = 5.7 Hz, 1H), 5.19 (d, J = 5.6 Hz, 1H).  ¹³C NMR (101 MHz, DMSO-d6) δ 139.43, 131.27, 127.28, 127.05, 126.91, 125.73, 69.75. LCMS = 214 [M⁺]

Fujiwara, T., Ohira, K., Urushibara, K., Ito, A., Yoshida, M., Kanai, M., Tanatani, A., Kagechika, H., Hirano, T. Steric structure–activity relationship of cyproheptadine derivatives as inhibitors of histone methyltransferase Set7/9. (2016) Bioorganic and Medicinal Chemistry, 24 (18), pp. 4318-4323.