[CH:1]1([OH:9])[CH2:8][CH2:7][CH2:6][CH:5]=[CH:4][CH2:3][CH2:2]1.C(OC)(=O)C1C=CC=CC=1.[OH-].[NH4+].C(OCC)C>C1CCCCC1.C(OCC)C.[N+]([O-])([O-])=O.[Ag+]>[CH:1]1([OH:9])[CH2:8][CH2:7][CH2:6][CH:5]=[CH:4][CH2:3][CH2:2]1(E)-cyclooct-4-enol was synthesized from (Z)-cyclooct-4-enol (H. Meier, W. Mayer, H. Kolshorn, Chem. Ber. 1987, 120, 685-689) by modification of previously published procedures (M. Royzen, G. P. A. Yap, J. M. Fox, J. Am. Chem. Soc. 2008, 130, 3760-3761; N. K. Devaraj, R. Upadhyay, J. B. Haun, S. A. Hilderbrand, R. Weissleder, Angew. Chem. 2009, 48, 7013-7016). 2 g (15.9 mmol) (Z)-cyclooct-4-enol and 2.2 g (16.3 mmol) methyl benzoate were dissolved in 250 mL cyclohexane/diethyl ether=1:9. The Petri dish was placed in an UVP-CL-1000-ultraviolet crosslinker reactor and irradiated for eight hours under ice-cooling. In intervals of 25-30 minutes the reaction mixture was passed through a column packed with 27 g of silver nitrate (10%) impregnated silica (commercially available from Aldrich). The mixture passing through the column was placed back into the UV crosslinker for further irradiation. After eight hours the irradiation was stopped and the silica was added to an ammonium hydroxide solution (28%, 160 ml). The suspension was stirred for 5 minutes, 160 ml of diethylether were added and stirring continued for 5 minutes. The aqueous layer was extracted with ether, the combined organic phases were washed with water and dried over magnesium sulfate. After evaporation of the solvents and flash chromatography (cyclohexane/ethyl acetate=1:1) two separated diastereomers of the product could be isolated. The main product 8b was obtained as a colourless oil (455 mg, 3.61 mmol, 23%) and used for further steps.
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