Electronic Effects of Heteroaromatic and Substituted Heteroaromatic Groups

Publisher Summary Organic chemists must frequently predict the chemical reactivity, equilibrium state, and various physical characteristics of many functional groups in heterocyclic systems. This can be done by correlation analysis within the framework of pσ-approach. Reviews published during the past two decades in Advances in Heterocyclic Chemistry have covered the various aspects of using these correlations in the heterocyclic series. The problems discussed in these reviews and monographs can be roughly divided into three groups: (1) the effects of annular heteroatoms on the properties of functional derivatives of heterocycles; (2) the effects of whole heterocyclic fragments on the properties of functional side-chain derivatives of heterocycles; (3) the effects of substituents in heterocycles on the properties of both heterocycles themselves (including the heteroatoms in these rings) and functional groups. This chapter is designed to fill this gap by systematizing the available data on the electronic effects of heteroaromatic groups as substituents. This chapter examines that, despite the diversity of heterocyclic systems and the complications involved in developing general concepts, it is possible to find for heteroaromatic systems certain quantitative dependences permitting correlation of the data on the reactivity of aromatic and heteroaromatic compounds on the basis of well-developed approaches. In heteroaromatic chemistry the quantitative investigation of reactivity remains a needed area of research. Despite the fact that a number of problems remain unsolved, the data reported in this chapter are expected to direct chemists interested in heterocycles to the large variety of work on the electronic effects of heteroaromatic groups.