| abstract |
The asymmetrical hydrogenation of 1-(4-methoxybenzyl)-3,4,5,6,7,8-hexahydroisoquinolinium salts to yield (S) or (R)-1-(4-methoxybenzyl)-1,2,3,4,5,6,7,8-hexahydroisoquinolinium salts can be effected with superior optical yield by the use of an iridium or rhodium complex catalyst comprising a chiral dipohsphine ligand of the general formula (I) or (II), (S)-1-(4-methoxybenzyl)-1,2,3,4,5,6,7,8-hexahydroisoquinoline and salts thereof are intermediate products in the manufacture of dextromethorphan, a known antitussive agent. |