FRITSCH, R and HARTMANN, E and BRANDL, G and MANNSCHRECK, A (1993) ABSOLUTE HELICITIES OF TWISTED 9,10-PHENANTHRENEQUINONES - CIRCULAR-DICHROISM AND CHEMICAL CORRELATION TO BIPHENYLS. TETRAHEDRON-ASYMMETRY, 4 (3). pp. 433-455. ISSN 0957-4166,
Full text not available from this repository.Abstract
The absolute configuration of the non-planar 9,10-phenanthrenequinone (-)546-18 was determined to be (M) by a four-step chemical correlation (Scheme 2) to the bridged biphenyl (-)365-10, the (M) helicity of which was proven via the circular dichroism of the conjugation band. The last step of the correlation consisted of the acyloin condensation of the diphenic ester (-)365-(M)-6, during which partial loss of optical purity was observed. An intermediate 9,10-bis(trimethylsiloxy)phenanthrene is thought to racemize at a moderate rate, thereby causing some loss of activity. ------ The relative configurations of twisted 9,10-phenanthrenequinones can be determined by means of a series of weak Cotton effects between ca. 370 and 500 nm (Tables 2 and 3). These are negative for (M) quinones, as shown by the above mentioned correlation to a bridged biphenyl. --------Liquid chromatography on optically active sorbents served for most of the semipreparative separations of enantiomers and determinations of enantiomeric purity.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ENANTIOMERS; BARRIERS; |
| Depositing User: | Dr. Gernot Deinzer |
| Last Modified: | 19 Oct 2022 08:42 |
| URI: | https://pred.uni-regensburg.de/id/eprint/54106 |
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