Studies on the reaction of N-(3-carbethoxy-4,5,6,7-tetrahydrobenzo[b]thien-2-yl)-N′-phenylthiourea with hydrazine hydrate (Part 1)

• Published in: Journal of heterocyclic chemistry Vol. 45; no. 2; pp. 467 - 473
• Main Authors: El-Sherief, Hassan A. H., El-Naggar, Galal M., Hozien, Zeinab A., El-Sawaisi, Suliman M.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley-Blackwell 01-03-2008; Wiley‐Blackwell
• ISSN: 0022-152X; 1943-5193
• DOI: 10.1002/jhet.5570450226

The reaction of N‐(3‐carbethoxy‐4,5,6,7‐tetrahydrobenzo[b]thien‐2‐yl)‐N′‐phenylthiourea (1) with hydrazine hydrate in 1‐butanol afforded a mixture of compounds 2, 3 and 4. Treatment of 3 and 4 with nitrous acid gave 6 and 8 respectively, while reactions of 3 with acetylacetone gave 7. Synthesis of tetracyclic compounds 9a‐f and 11 from the reactions of 3 with ethyl orthoformate or appropriate acids, acid chloride, carbon disulphide and/or ethyl chloroformate. Also its reaction with isothiocyanate derivatives gave the corresponding thiosemicarbzides 12a,b which on, refluxing in alcoholic KOH gave the unexpected tetracyclic products 14a,b. Similarly the tetracyclic compounds 16a‐e and 19 were obtained by cyclization of 4 and 18 respectively.