Abstract: The present invention provides a method of preparing thieno[3,2-c]pyridine derivatives of formula I: ##STR1## wherein R.sub.1 is selected from the group consisting of lower alkyl; lower alkylene phenyl; substituted lower alkylene phenyl wherein the phenyl is substituted from 1 to 3 times with lower alkyl, lower alkoxy, lower acyloxy, hydroxy, nitro and halo; lower alkylene naphthyl, lower alkylene thienyl; lower alkylene diphenyl; lower alkylene-hydroxy-phenyl; substituted lower alkylene-hydroxy-phenyl wherein the phenyl is substituted from 1 to 3 times with lower alkyl, lower alkoxy, lower acyloxy, hydroxy, nitro, and halo; lower alkylene-hydroxy-naphthyl; lower alkylene-hydroxy-thienyl; lower alkylene-hydroxy-diphenyl, and R.sub.2 is H or lower alkylene. The method comprises reacting a compound of a formula II: ##STR2## with a cyclic dioxy or cyclic dithio in the presence of catalyst.

Abstract: The present invention provides a process for preparing compounds of Formula I: ##STR1## wherein R.sub.1 is methyl by reduction of a camphene intermediate with a reducing agent.

Abstract: N-(5-thioxo-L-prolyl)-L-cysteine and derivatives thereof, having interesting mucolytic-expectorant, antioxidant (radical-scavenger), antielastase, antiemphysema, immunostimulating and hepatoprotective activities and a low toxicity are described, as well as processes for the preparation thereof and pharmaceutical formulations for the use in therapy.