Synthesis of 2‐formyl‐1‐aza‐dibenzo[ e , h ]azulenes

ynthesis of a novel heterocyclic class of compounds, 1‐aza‐dibenzo[ e , h ]azulenes [1] ( 6a‐c and 7a‐c ), derived from dibenzo[ b , f ]oxepin, its 8‐chloro analogue and dibenzo[ b , f ]thiepin, respectively, is described. Aldol condensation of the starting ketones 4a‐c with (dimethyl‐hydrazono)‐acetaldehyde affords hydrazonoethylidene derivatives 5a‐c , which on reduction with sodium dithionite and subsequent cyclization provide the target tetracyclic 1‐aza‐dibenzo[ e , h ]azulenes 6a‐c . Regiospecific formylation of 6a‐c with Vilsmeier reagent leads to 2‐formyl derivatives 7a‐c . A series of derivatives 6a‐c and 7a‐c was tested for antiinflammatory activity as potential inhibitors of tumor necrosis factor alpha (TNF‐α) production in vitro .