3 9 g was purified by column chromatography on silicagel 600 ml using a mixture of ethyl acetate and heptane 1 6 as eluent which afforded 1 62 g 34 of 3 10 11 dihydro 5h dibenzo b f azepin 2 yl acrylic acid tert butyl ester as a solid to a solution of the above tert butyl ester 600 mg 1 9 mmol in dioxane 15 ml was added lithium hydroxide hydrate 400 mg 9 3 mmol and water 15 ml the reaction mixture was stirred at reflux temperature for 16 h the cooled reaction mixture was decanted and diluted with water 60 ml acidified with 5n hydrochloric acid to ph 1 the precipitate was filtered off washed with water 3 u00d7 15 ml and dried in vacuo affording 409 mg 82 of the title compound as a solid calculated for c 17 h 14 no 2 c 77 25 h 5 34 n 5 30 found c 76 98 h 5 86 n 5 09 1 h nmr 200 mhz dmso d 6 u03b4 h 2 98 s 4h 6 28 d 1h j h 15 7 hz 6 74 dt 1h 7 04 m 4h 7 38 m 2h 7 46 d 1h j h 15 7 8 74 1 h s nh 12 05 bs 1 h hplc retention.