Substituent effect study on 13Cβ SCS of styrene series. A Yukawa–Tsuno model and Reynolds dual substituent parameter model investigation

摘要: The Yukawa–Tsuno (Y–T) and Reynolds dual substituent parameter (DSP) models have been used to model 13C chemical shift (SCS) of the Cβ atom 19 series para-substituted styrenes (X-C6H4CRCYW) with variable electronic structural demands in side-chain. best fit Y–T was better than that DSP for most studied series. A high correlation found between ρ value ρF model. value, which reflects sensitivity 13Cβ SCS field effect, be influenced by group W on atom. enhances para-substituent π-polarization side-chain has a higher its counterpart groups induce counter an E-configuration aryl ring corresponding Z lower is observed when induces (as NO2 COMe) or R imposes 65° dihedral angle benzene t-Bu). When heterocyclic ring, closer heteroatom Cβ, due greater π-polarization. two components effect SCS, namely resonance behave inversely. demand (r+ value) increases, as Y and/or become more electron-withdrawing (EW). hetrocyclic develop negative charge at carbon adjacent (and styryl moiety attached) r+ those fail do so. lowest angle. Copyright © 2007 John Wiley & Sons, Ltd.