(R)-1-Phenyl-1,2,3,4-tetrahydroisoquinoline is the counterpart to (S)-1-Phenyl-1,2,3,4-tetrahydroisoquinoline, the latter enantiomer being a key intermediate in the preparation of Solifenacin (S676700), an antimuscarinic agent. Since (R)-1-Phenyl-1,2,3,4-tetrahydroisoquinoline is produced as a by-product, it has been suggested that it should be recycled in order to obtain the S enantiomer on a larger scale. (R)-1-Phenyl-1,2,3,4-tetrahydroisoquinoline is also used as a reagent to prepare quinuclidin-3-yl 1,2,3,4-tetrahydroisoquinoline-2-carboxylate derivatives, compounds that act as muscarinic receptor antagonists.
