Methyl 1-cyclohexyl-6,7-dimethoxy-3,4-dihydroisoquinoline-3-carboxylate

There are two independent molecules in the asymmetric unit of the title compound, C19H25NO4. A single C—H⋯π interaction and various intermolecular contacts (2.65–2.83 Å) link the independent molecules in the crystal structure. The N-containing six-membered ring assumes a twisted half-boat conformation.

There are two independent molecules in the asymmetric unit of the title compound, C 19 H 25 NO 4 . A single C-HÁ Á Á interaction and various intermolecular contacts (2.65-2.83 Å ) link the independent molecules in the crystal structure. The N-containing six-membered ring assumes a twisted half-boat conformation.  Table 1 Hydrogen-bond geometry (Å , ).

Comment
The title compound is a precursor in the synthesis of novel chiral catalysts containing a tetrahydroisoquinoline framework.
Upon oxidation of the sp2 hybridized nitrogen, the oxide form of this compound and derivatives are currently being tested in our laboratory as novel organocatalysts for asymmetric allylation reactions (Naicker et al. 2010a).
The structure has triclinic (P1) symmetry with two molecules in the asymmetric unit (Fig. 1). These two molecules are linked by various intermolecular short contact interactions and one C-H··· π (C2B-C7B ring) bond (Table 1). The crystal packing reveals that via the centre of symmetry operation the enantiomer generates its mirror image. This results in a layered packing along the a axis (Fig. 2).
From the crystal structure it is evident that the N-containing six membered ring assumes a twisted half boat conformation ( Fig. 1). This heterocyclic ring within similar structures displays either a half chair ((Naicker et al. 2010b) or half boat (Naicker et al. 2011) conformation. A possible reason for the change is the introduction of the sp2 hybrized nitrogen atom.
As anticipated the cyclohexane moieties adopt chair conformations.