Syntheses and interconversions of some s-triazolo[3,4-a]isoquinolines

s-Triazolo[3,4-a]isoquinoline (II) and its 3-methyl analogue (III) have been synthesized from 1-isoquinolylhydrazine (I) by cyclisation with formic and acetic acid. The 3-hydroxy derivative (IV) has been shown to exist in the lactam form. Methylation with methyl iodide gave the N-methyl derivative (V). Dimethyl sulphate and diazomethane also led exclusively to the same product. The O-methyl derivative (IX) could be obtained only through the 3-chloro compound (VIII). The chlorine atom in VIII undergoes nucleophilic replacement easily. The 3,6-dichloro derivative (X) has also been prepared. Several interconversions in the series are described. Aryl hydrazones (XVIII) prepared from (I) have been oxidatively cyclised to give 3-aryl-s-triazolo[3,4-a]isoquinolines (XIX). U.V., I.R. and P.M.R. spectra have been recorded and used for assignment of structures in some cases.