Abstract: The present invention relates to stereospecific processes for the preparation of enantiomers of 3-substituted-furo[3,4-c]pyridine of formula I, wherein R.sub.3, R.sub.4 and R.sub.6 stand for various substituents, comprising the steps of: oxidation of a racemic pyridine derivative of formula II, reduction of the resulting ketone with a reducing agent, sterospecific locking or blocking of the OH group of the enantiomer alcohol, opening of the acetonide ring and cyclization of the resulting compound. ##STR1##The present invention also relates to compounds thus obtained and therapeutical compositions thereof.

Abstract: This invention relates to catechol derivatives having the general formula ##STR1## wherein R represents various substituents, to a process for the preparation of the same comprising reacting S-(3,4-dihydroxyphenyl)-isothiourea, which has the formula II, with a tosylate of the general formula III ##STR2## and to therapeutical compositions wherein the active ingredient is one of these compounds.

Abstract: This invention relates to bicyclic catechol derivatives having the general formulae I and II ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and Z represent various substituents, to a preparation process of the same comprising reacting a compound of formula III ##STR2## wherein R.sub.1 and R.sub.2 have the meanings given above with an appropriately substituted propionic or butyric acid (or an ester or a salt of the same) of formula IV ##STR3## wherein R.sub.3 has the meaning given above, and to therapeutical compositions wherein the active ingredient is one of these compounds.

Abstract: This invention relates to new chiral organoboranes of the general formula ##STR1## in which X represents a methylene group or a sulphur atom, n and p are 0 or 1, and to a preparation process of these compounds, consisting in reacting a bicyclic substituted di- or tri-thiane with a borane such as B.sub.2 H.sub.6 or BH.sub.3 : Lewis base.