Diastereomers Composed of Two Planar-Chiral Subunits: Bis([2.2]paracyclophan-4-yl)methane and Analogues
✍ Scribed by Ludger Ernst; Lars Wittkowski
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 383 KB
- Volume
- 1999
- Category
- Article
- ISSN
- 1434-193X
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✦ Synopsis
A series of compounds Q 2 Z was prepared, where Q = [2.2]-separately. The configurations of 5m/5c, 6m/6c, and 8c were directly determined by NMR spectroscopy, that of 4m/4c paracyclophan-4-yl and Z = C(=O) (4), CH 2 (5), SiMe 2 (6), S (7), P(=O)OMe (8), and C(=O)C(=O) (9). Because of the indirectly by reducing the separated compounds to 5m and 5c, respectively, and that of 7m by X-ray diffraction. The planar chirality of Q, these compounds occur as meso-(m) and chiral (c) diastereomers, which were formed in equal favoured conformations of 4-8 were studied by molecular mechanics computations by using the MM3(94) program. An amounts. They were separated in the cases of 4-7 and enriched in the case of 9 (diastereomeric ratio ca. 7:3).
attempt was made to rationalize some chemical shift differences between diastereomers on the basis of the Compound 8 possesses a pseudoasymmetric phosphorus centre and occurs as one chiral (8c) and two meso conformers predicted. diastereomers (8m 1 , 8m 2 ), all three of which were isolated CEPCs of equal configuration [6] (S,S isomer shown in 1, [a] Institut für Organische Chemie der Technischen Universität Braunschweig, to repeat the synthesis of 3 in order to investigate its NMR Hagenring 30, D-38106 Braunschweig, Germany properties more closely were unsuccessful.