... The formylmethylidene deriva- tive 6 was synthesized by a Wittig reaction followed by a Vilsmeier ... SYNTHESIS 1261 Methyl 11-Oxo-6,11-dihydrodibenz[b,e]oxepin-2-carboxylate (2): To a ... Dimethyl-2-nitroformanilide (14): To chilled HCOZH (50 mL) was added Ac2O (10 mL), the ...