Sterically crowded cyclohexanes - 71). synthesis,crystal structure,conformation and dynamics of hexaspiro[2.0.3.0.2.0.3.0.3.0.3.0]docosane and hexaspiro[2.0.3.0.3.0.3.0.3.0.3.0]tricosane

The synthesis, crystal structure, conformation and dynamics of hexaspiro2.0.3.0.2.0.3.0.3.0.3.0]docosane 6 and hexaspiro2.0.3.0.3.0.3.0.3.0.3.0]tricosane 7 are described. Both compounds adopt a chair conformation in the solid state and in solution. Their barriers of inversion were inaccessible by DNMR but could be determined from equilibration studies with stereoselectively labeled l-¹3C]-6 and l, l-D₂]-7. The results were as follows: l-¹³C]_a,e -6 ΔG³₃₃₉ = 112.1 kJ/mol and l,l-D₂]_a,e -7: ΔG³₄₂₃ = 136.0 kJ/mol. The stereoisomers of l-¹³C]-6 and l,l-D₂]-7 thus represent two further examples of conformational isomerism within the cyclohexane family.