Molecular conformations. Part VII. The bicyclo[3,3,1]nonane system: X-ray analysis of 9-benzoyl-3α-bromo-2β-hydroxy-9-azabicyclo[3,3,1]-nonane

Abstract

Whereas simple bicyclo[3,3,1]nonanes lacking substituents at positions 3 and 7 adopt flattened twin-chair conformations, 9-benzoyl-3α-bromo-2β-hydroxy-9-azabicyclo[3,3,1]nonane is an example of a bicyclo[3,3,1]nonane skeleton with a boat-chair conformation. The dimensions of the molecule have been determined by X-ray crystal structure analysis, and the distortion from ideal cyclohexane ring geometry is less than that in the twin-chair bicyclo[3,3,1]nonanes. The crystals are monoclinic, of space group P2₁/c, with four molecules of C₁₅H₁₈BrNO₂ in a unit cell defined by a= 8·68, b= 20·26 Å, β= 100° 30′. The atomic co-ordinates were obtained by Fourier and least-squares calculations; the final value of R was 11·2% over 2448 reflections.