A synthesis of dibenzo [b, f] thiepin derivatives using 2-iodophenylacetic acid (X) as the precursor of the A ring is described. Condensation of this acid with potassium salts of 4- aminothiophenol and 4-methylselenothiophenol (XXII) produced acids XI and XXV which were cyclized by polyphosphoric acid to 8-amino (XIV) and 8-methylseleno-llH-dibenzo [b, f] thiepin-l0-one (XXVI). The usual reaction sequences then led to the synthesis of 8- ...