| abstract |
Therapeutic intermediates exhibiting also anti-convulsive properties in animal experiments, consist of 3-carboxy-1-thia-isochroman-1,1-di oxide derivs. (I): (where R1 and R2 are lower alkyl and R3 is H or alkyl). Prepd. (a) by reacting cpds. (II): (where R4 is -COOH, carboxylate, carbamoyl or carbonitrile and Hal is halogen) with conc. H2SO4 at room temp., diluting and heating for example to 70-90 degrees C or (b) by saponifying 3-carbamoyl- or 3-carboxylate derivs. of (I) in diluted inorganic acids, such as HCl or H2SO4. |