Whitby group

To a stirred solution of 4-phenyl-4,5-dihydro-3H-1,2,4-triazole-3,5-dione (150 mg,  0.5 mmol), boron trifluoride diethyl ether complex (347 mg, 3.0 mmol) dissolved in dichloromethane (1.0 mL), at -78 °C, 4-[(E)Butylidene]-3-[(Z)-1-(methylthio)methylidene]-1-(phenylmethyl)perhydroazepine (396, 150 mg, 0.5 mmol) was added dropwise, warmed to room temperature, refluxed at 36 °C for 20 minutes.  The product extracted with diethyl ether (3 x 30 mL), the combined organic layer washed with water (3 x 30 ml) and brine (30.0 mL), dried MgSO_4, filtered and the solvent removed under reduced pressure.  Radial chromatography (SiO₂, 5-100% diethyl ether:ethyl acetate including 5 % Et₃N) afforded the title compound as a viscous oil (35 mg, 0.075 mmol, 15 %).