Fritsch, R. and Hartmann, E. and Andert, D. and Mannschreck, Albrecht (1992) Helical Phenanthrenes 3: Syntheses, Enrichment of Enantiomers, and Barriers to Racemization of Twisted 9, 10-Phenanthrenequinones. Chemische Berichte 125 (4), pp. 849-855.
Full text not available from this repository.
The known syntheses of the 9, 10-phenanthrenequinones 10a – c were improved by the chlorotrimethylsilane modification of the acyloin condensation of biaryl diesters. The novel quinones 4a, 4b, and 12 were prepared. For the first time, enantiomers (M and P) of this class of compounds were enriched semipreparatively by liquid chromatography on optically active sorbents. The barriers to thermal racemization amount to 90 – 130 kJ mol-1 (Table 2) and are thus higher than the barriers for the corresponding phenanthrene hydrocarbons by roughly 20 kJ mol-1. The reasons for this increase are discussed in terms of repulsive interactions in the transition state of helix inversion.
|Additional information (public):||späterer Zeitschr.titel: European journal of inorganic chemistry|
|Institutions:||Chemistry and Pharmacy > Institut für Organische Chemie > Retired Professors > Prof.Dr. Mannschreck|
|Keywords:||9, 10-Phenanthrenequinones; Acyloin condensation; Enantiomers, liquid chromatography of; Barriers to racemization|
|Subjects:||500 Science > 540 Chemistry & allied sciences|
|Created at the University of Regensburg:||Unknown|
|Deposited On:||15 Nov 2010 14:47|
|Last Modified:||15 Nov 2010 14:47|