Synthesis, characterization and stereochemistry of N-acyl-r-2,c-4-bis(4-methoxyphenyl)-3-azabicyclo[3.3.1]nonanes

Four new N-acyl-2,4-bis(4-methoxyphenyl)-3-azabicyclo[3.3.1]nonanes 3-6 have been synthesized. The structural characterization and the conformational preferences of the compounds 3-6 have been carried out using IR, 1D and 2D NMR and Mass spectral data. The NMR spectral data indicates that the N-acyl-2, 4-bis(4-methoxyphenyl)-3-azabicyclo[3.3.1]nonanes 3-6 prefer to exist in twin-chair conformation with partial flattening at nitrogen end. To avoid A(1,3)-strain, the anisyl groups at C-2 and C-4 are forced to occupy the quasi-axial orientation. X-ray crystal structure of the N-dichloroacetyl-2,4-bis(4-methoxyphenyl)-3-azabicyclo[3.3.1]nonane 6 also supports the similar conformation in the solid state. (C) 2015 Elsevier B.V. All rights reserved.