Substituent effects on the carbon-13 NMR chemical shifts of cyclopropyl carbons in P-substituted(CIS-and trans-2-chlorocyclopropyl)benzenes

Article abstract of DOI:10.1246/bcsj.63.2836

Carbon-13 chemical shifts have been measured for the cyclopropyl carbon atoms of twenty one p-substituted (cis- and trans-2-chlorocyclopropyl)benzenes. The substituent induced chemical shifts (SCS) for the trans derivatives are shifted down field by electron-acceptor substituents and upfield by electron-donating substituents (normal SCS). This SCS trend is the same as those observed for the p-substituted cyclopropylbenzenes, while the SCS range is small because of the decreased polarization of C-1-C-2 bonding due to the attached chlorine atom. For the cis derivatives, SCS for C-1 and C-3(CH ₂) carbons were also normal, while no measurable SCS was observed for C-2(CCl). The SCS well fitted with the LSFE equation, indicating that the SCS were controlled mainly by a polar effect, except for C-2(CCl, cis).