1: (chloromethyl)-triphenylphosphonium chloride With n-butyllithium in tetrahydrofuran; hexane T=0°C; 1 h; 2: 7-acetylbenzo[b]oxepine-3-one in tetrahydrofuran; hexane T=0°C; Wittig olefination; 0.5 h; Further stages. Title compound not separated from byproducts.;