Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Tricarbonylchromium Complexes of Chiral [2.2]Metacyclophanes: Syntheses, Structures, and Chiroptical PropertiesHPLC-baseline separations of three racemic cyclophanes 3, 4, and 6 on cellulose tris(3,5-dimethylphenyl)carbamate led to their enantiomers with high optical purity. Complexation of (-)-3 and (+)-3 with triamminetricarbonylchromium yielded chiral Cr(CO)3 complexes (-)-(S)P-(3S)M-3a and (+)-(R)P-(3R)M-3a stereoselectively. Derivatisation of the complexes by lithiation and reaction with electrophiles gave new substituted chiral Cr(CO)3 complexes of [2.2]metacyclophanes regio-selectively. X-ray structure analyses of one chiral chromium complex (-)-(R)P-(5S)M-14a and three chiral chromium-free ligands (-)-(S)P-3, (-)-(S)P-4, and (-)-(S)P-6 led to the assignment of the absolute configurations of all chiral compounds discussed here. The influences of substituents on the chiroptical properties are investigated. The helicity of [2.2]metacyclophanes is discussed. For the first time X-ray structure analyses were performed of a bis-Cr(CO)3 complex (9a) as well as of the first chromium complex 10a of a heteraphane. Dethioketalisation of (-)-(S)P-3 with NBS gave (-)-(S)P-18, the absolute chirality of which has been known, under retention of configuration.
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