Synthesis and some reactions of 11-azacyclohept〔a〕azulen-3(3H)-ones and evaluation of their cytotoxic activity against HeLa S3 cells

Aldol condensation of 2,3-diformyl-1-azaazulene with acetone, methoxyacetone, and benzylacetone in aq. NaOH solution gave corresponding 11-azacyclohept[α]azulen-3(3H)-one (2a), 2-methoxy-derivative (2b) and 2-benzyl-derivative (2d) in good yields. Hydrolysis of 2b using hot HBr gave 2-hydroxy-11-azacyclohept[a]azulen-3(3H)-one (2f). Acetylation of 2f gave 2-acetoxy-11-azacyclohept[α]azulen-3(3H)-one (2g). Reaction of the compounds (2a, 2b, 2f) with diethyl malonate in Ac 2 O under heating gave 1,9(11bH)-11b-azaazuleno[1,2,3-cd]azulenedione derivatives (4a, 4b, 4f). Compounds (2b, 2f) showed weak cytotoxic activity against HeLa S3 cells.