Optically active diaryl tetrahydroisoquinoline derivatives.

In (1R,3S)-6,7-dimethoxy-3-(methoxydiphenylmethyl)-1-phenyl-1,2,3,4-tetrahydroisoquinoline, C(31)H(31)NO(3), (I), and (1R,3S)-2-benzyl-3-[diphenyl(trimethylsiloxy)methyl]-6,7-dimethoxy-1-phenyl-1,2,3,4-tetrahydroisoquinoline, C(40)H(43)NO(3)Si, (II), the absolute configurations have been confirmed to be R and S at the isoquinoline 1- and 3-positions, respectively, by NMR spectroscopy experiments. Both structures have monoclinic (P2(1)) symmetry and the N-containing six-membered ring assumes a half-chair conformation. The asymmetric unit of (I) contains one molecule, while (II) has two molecules within the asymmetric unit. These structures are of interest with respect to the conformation around the exocyclic C-C bond: (I) displays an ap (antiperiplanar) conformation, while (II) displays an sc-exo (synclinal) conformation around this bond. These conformations are significant for stereocontrol when these compounds are used as catalysts. Various C-H...π and C-H...O bonds link the molecules together in the crystal structure of (I). In the crystal structure of (II), three intermolecular C-H...π hydrogen bonds help to establish the packing.