Thermal racemisation of [6], [7], [8] and [9] helicene.

✍ Scribed by R.H. Martin; Marie-Jeanne Marchant

• Book ID: 104245222
• Publisher: Elsevier Science
• Year: 1972
• Tongue: French
• Weight: 114 KB
• Volume: 13
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)94141-3

✦ Synopsis

Wi wish to report that [6], 171, [8] and [S]helicene undergo thermal racemisatlon when heated, in evacuated sealed tubes, slightly above the melting points of the respective pure antipodes b). [9]Helicene [a]57g-14300 is thus completely racemised in 10 minutes at 380'. Pure optically inactive [9]helicene (NMR and IR) was recovered by chromatography in over 85% yield.

Following this rather surprising observation , we have undertaken the kinetic study of these racemisations, starting with [6]helicene (vide infra).

Newman and Lednicer 1) briefly reported, in 1956, that "partial