Urea → 3-Cyano-8-fluorodibenzo[b,f]thiepine

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Reaction Steps

Suspend 6 gm. of the 3-cyano-8-aminodibenzo[b,f]thiepine from Example 18, Step 1, in 15 ml. of 50% fluoboric acid (HBF4) and 15 ml. of water. Cool the mixture to 3°-5° C. and slowly add 18 ml. of 10% sodium nitrite. Stir in the cold for 4 hours and add urea to destroy the excess sodium nitrite. Separate the solids by filtration and wash with cold 5% fluoboric acid followed by cold water and then ether. Air dry. Suspend the diazonium fluoroborate in 300 ml. of xylene and reflux for 2 hours with stirring. Filter and evaporate the filtrate to dryness. Triturate with ether to obtain the title product (m.p., 146°-148° C.).

Provenance & Evidence