To a solution of compound 2-iodo-4-(1-methylpiperidin-4-yloxy)-9,10-dihydro-4H-3,10a-diaza-benzo[f]azulene (example 2A) (100 mg, 0.24 mmoles) in DMF (2.5 mL) in a screw-capped vial under argon are added Pd(OAc)2 (5.4 mg, 24 μmole), PPh3 (16 mg, 60 μmole), tert-butylacrylate (175 μL, 0.96 mmole) and NEt3 (140 μL, 0.88 mmole). The reaction mixture is heated at 100° C. overnight. Water is added to the reaction mixture and pH adjusted to 9-10 by adding concentrated ammonia solution. The aqueous phase is extracted three times with CH2Cl2. The organic phase is dried over magnesium sulphate, filtered and the solvent is removed under reduced pressure. The residue is pre-purified by silica gel chromatography using (CH2Cl2:MeOH:NH4OH) as eluent with a gradient from (98:2:0.1) to (96.5:3.5:0.35) and the residue is submitted to a preparative thin-layer chromatography eluting with (CH2Cl2:MeOH:NH4OH) (9:1:1) to afford 3-[4-(1-methylpiperidin-4-yloxy)-9,10-dihydro-4H-3,10a-diaza-benzo[f]azulen-2-yl]-acrylic acid tert-butyl ester.
