Sterically crowded cyclohexanes—10 Synthesis, conformation and dynamics of 8,8,13,13-tetramethyltetraspiro[2.0.3.1.3.1.3.0]heptadecane

✍ Scribed by Beate Rissom; Lutz Fitjer

• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 522 KB
• Volume: 53
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(97)00440-7

✦ Synopsis

The synthesis, conformation and dynamics of 8,8,13,13-tetramethyltetxaspiro[2.0.3.1.3. l.-3.0]heptadecane (11) are described. 11 adopts a chair conformation in solution. Its barrier of inversion proved inaccessible by DNMR but could be determined from equilibration studies with stereoselectively labeled [1-13C]~-11. The results were as follows: AI.~ = 104.7 kJ/mol, AS s = -13.1 J/mol.K and AG*29s = 108.6 kJ/mol. The stereoisomers of [l-13Cle,a-ll thus represent a further case of conformational isomerism within the cyclohexane family.