| abstract |
The compounds of general formula II are new and represent important intermediates in the synthesis of tapentadol. In the synthesis of tapentadol of formula I and its pharmaceutically acceptable salts, O-protected (2R,3R)-acids of general formula II, in step A, are reacted in an inert organic solvent with an activating agent, optionally in presence of a catalyst or a base; in step B, the obtained compounds of general formula V, wherein R has the above mentioned meaning and X stands for chlorine or alkoxycarbonyloxyl group O-CO-OR 1 or pivaloyloxyl O-CO-t-Bu group, wherein R 1 is methyl or ethyl, are reacted with dimethylamine or its salts optionally in presence of a base; in step C, the obtained N, N-dimethylamides of general formula VI, wherein R has the above mentioned meaning, are reduced by means of hydride agents in a suitable solvent; in step D, the produced alkeneamines of general formula VII, wherein R has the above mentioned meaning, are hydrogenated on a metal catalysts in a suitable solvent; and, finally, in step E, the produced alkaneamines of general formula VIII, wherein R has the above mentioned meaning, are O-dealkylated by means of dealkylating agents, and, if required, the obtained tapentadol is converted by the action of a pharmaceutically acceptable acid to respective salts, e.g. hydrochloride. |