ISSN:
0021-8383
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
On the Transmission of Substituent Effects in Fluorenes and FluorenonesA series of 2- and 2,7-substituted fluorenes (1) and fluorenones (2) were prepared either by electrophilic substitution (1c-f, h-j; 2c, d, j), reduction (1, 2k, l) or nucleophilic exchange (1g, m, n; 2m) via respective diazonium compounds as well as by oxydation (2e-h, n) of the hydrocarbons (1).The carbon-13 n.m.r. spectra for the fluorene (1a-n) and fluorenone (2a-n) derivatives was analyzed using a dual substituent parameter (DSP) equation. The substituent chemical shifts (SCS) of the carbon atoms 4a, 4b, 7 and 4a, 4b, 7, 9 of eleven fluorenes and nine fluorenones, respectively, correlate with the f, r substituent constants and with σI, σR0 ones in a satisfactory manner. The comparison indicates that the correlation with the f, r constants yields always a higher resonance contribution than the calculation with σI, σR0 constants. The DSP analysis reveals that transmission of the substituent effect to the substituted ring is primarily resonance controlled while the transmission to the second ring involves a π-bond polarization mechanism. For C-4b in the unsubstituted ring a reversed substituent effect was found. In contrast to fluorenes in fluorenones the transmission of the substituent effect involves the carbon atom 9.
Additional Material:
4 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19883300306
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