Synthesis
General procedure for the synthesis of 4-hydroxycyclooctene from 4-hydroxycyclooctene: Reagent grade ether (500 mL) was added to a Teflon-lined quartz flask containing (Z)-cyclooct-4-enol (1 g, 7.9 mmol) and methyl benzoate (1.1 g, 7.9 mmol) with a PTFE-coated magnetic stir bar. The quartz flask was placed in a Rayonet reactor and connected via Teflon PTFE tubing to a column containing 40 g of ISCO RediSep silica gel and an FMI pump. The column was filled with an 8 cm high bed of dry silica gel, silver nitrate impregnated silica gel (16.8 g, 10% w/w, 9.9 mmol AgNO3) was placed at the top of the column, and the column was rinsed with ether. The pump circulation rate was adjusted to approximately 100 mL/min for an 8 h photolysis reaction. The column was washed with 200 mL of ether and dried by a stream of compressed air. The column contents were poured into a 500 mL conical flask and the silica gel was stirred with 200 mL ammonium hydroxide and 200 mL methylene chloride for 5 minutes. The silica gel was filtered and the filtrate was transferred to a dispensing funnel. Separate the organic layer and wash the ammonium hydroxide layer with 200 mL of methylene chloride. The organic layers were combined, washed with 100 mL of water and dried with MgSO4. The solvent was evaporated by decompression to give the title product as a 2:1 mixture of diastereoisomers in a yield of 0.73 g (73%). The experiment was repeated to give 0.72 g (72%). The two diastereoisomers were separated in trace amounts by gravity silica gel column chromatography (4:1 pentane:ether): rf = 0.42 (major diastereoisomer: rf = 0.30).
References
[1] Patent: US2009/23916, 2009, A1. Location in patent: Page/Page column 15
[2] Monatshefte fur Chemie, 2016, vol. 147, # 3, p. 579 - 585
[3] Angewandte Chemie - International Edition, 2014, vol. 53, # 38, p. 10242 - 10246
[4] Angew. Chem., 2014, vol. 126, # 38, p. 10407 - 10412,5
[5] Patent: US2016/115180, 2016, A1. Location in patent: Paragraph 0139
