Singh, Shyam (1972)
The synthesis and stereochemistry of some 8,8-disubstituted 1,1-binaphthyls, bridged and unbridged.
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In the present work, starting from 8,8'-bisbromomethyl-1-binaphthyl, the following new compounds were prepared. 1,1'-Binaphthyl-8,8'-diacetic acid was resolved through its quinine salt and Arrhenius parameters and Transition State Theory Functions for racemisation were determined for it. Another unbridged compound, 1,1'-binaphthyl-8,8'-bis(methylenepyridinium)diiodide, was obtained optically active from optically active 8,8'-bisbromomethyl-1,1'-binaphthyl.8,8'-Bridged carbocyclic compounds were obtained in optically active forms from the resolved dinaphtho [8,1-ab, 1',8'-de]-cyclonona-2,4-diene-8,8-dicarboxylic acid. All these optically active carbocyclic compounds were found to be optically stable even when melted.8,8'-Bridged N-heterocyclic compounds were obtained optically active by using as optically active precursor the 8,8'-bisbromomethyl-1,1'-binaphthyl and were also found optically stable up to their decomposition points.The main features of the ultra-violet absorption spectra in 95%ethanolic solution of all 8,8'-bridged 1,1'-binaphthyls correspondwith those of the parent compound, 1,1'-binaphthyl.Optical rotatory dispersion(o.r.d.) and circular dichroism(c.d.) spectra of the optically active compounds were studied in 95% ethanol. From these chiroptical studies, and by correlation with other workers'assignments, it is shown that absolute configuration can be assignedin the short-wave region below the short-wave ultra-violet absorptionband. A short-wave positive Cotton effect (o.r.d) corresponds to the S-configuration and a negative Cotton effect corresponds to the R-configuration. Previously assigned by chemical correlation from a compound of known absolute configuration by X-ray crystal analysis (Akimoto,Shioiri, Iitaka and Yamada, 1968), Previously assigned by chemical correlation with a compound whose configuration was assigned after asymmetric reduction of a ketone with a reagent of known absolute configuration (Mislow and McGinn, 1958). Our optical rotatory dispersion and circular dichroism observations are related to these absolute assignments, and hence the configurations of the new optically active compounds are determined.
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Institution: University of London, Bedford College (United Kingdom).