Geometric isomerism in substituted 4-picolyl carbanions: a probe for ranking the charge demands of electron-withdrawing groups

摘要: Chain-sustituted b-picolyl carbanion sodium salts were prepared in DMSO and their 13 C NMR spectra investigated to monitor the competitive partitioning of negative charge between substituent pyridyl ring. The anisochrony C(3) C(5) carbon atoms heterocycle Ph-, PhS-, CN-, PhSO-substituted carbanions 1 - -4 probe double bond carbanionic C(4) ring