Indazole, oxathiadiazole, and thiadiazine derivatives from thiosemicarbazides

Abstract

4-Substituted thiosemicarbazides 1a–c reacted with 2,3-dicyano-5,6-dichloro-1,4-benzoquinone (DDQ, 2), 2,3,5,6-tetrachloro-1,4-benzoquinone (CHL-p, 6) and 2,3-dichloro-1,4-naphthoquinone (DCHNQ, 7) in ethyl acetate with admission of air and form the derivatives of 1,5,2,3-oxathiadiazole 8a–c, indazole 9a–c, 1,3,4-thiadiazine-6-one 10a–c, 1,3,4-thiadiazaphenanthren-9-one 11a–c, naphtho[1,2-e:4,3-è]bis1 3 4thiadiazine 12 and dibenzo[b,i]thianthrene-5,7,12,14-tetraone 13. A rationale for the conversions observed is presented.

Keywords:

• Thiosemicarbazides
• Quinones
• Indazole
• Oxathiadiazole derivatives
• Thiadiazine derivatives

Acknowledgements

A. A. Hassan is indebted to the A. V. Humboldt-Foundation for the donation of the Shimadzu 408 IR spectrophotometer. Dedicated to Professor Dietrich Döpp on the occasion of his 65th birthday.