Whitby group

To a stirred solution of methyl propriolate (84.0 mg, 1.0 mmol) and boron trifluoride diethyl ether complex (0.40 mL, 3.0 mmol) dissolved in dichloromethane (1.0 mL) at –78 °C, 4-[(E)Butylidene]-3-[(Z)-1-(methylthio)methylidene]-1-(phenylmethyl)perhydroazepine (396, 0.304 g, 1.0 mmol) was added dropwise, warmed to room temperature and refluxed for 1 hrs.  The product was extracted into diethyl ether (3 x 30 mL), the combined organic layer washed with water (3 x 30 mL), brine (30.0 mL), dried over MgSO₄, filtered and solvent removed under reduced pressure.  The title compound was isolated as a pale oil (162 mg, 0.48 mmol, 48 %).