"The question of how one chooses appropriate carbon-carbon bond disconnections is related to functional group manipulations since the distribution of formal charges in the carbon skeleton is determined by the functional group(s) present. The presence of a heteroatom in a molecule imparts a pattern of electrophilicity and nucleophilicity to the atoms of the molecule. The concept of alternating polarities or-latent polarities (imaginary charges) often enables one to identify the best positions to make a disconnection within a complex molecule. Functional groups may be classified as follows: E class: Groups conferring electrophilic character to the attached carbon (+) … G class: Groups conferring nucleophilic character to the attached carbon (-) … A class: Functional groups that exhibit ambivalent character (+ or -) … The positive charge (+) is placed at the carbon attached to an E class functional group … and the TM is then analyzed for consonant and dissonant patterns by assigning alternating polarities to the remaining carbons. In a consonant pattern, carbon atoms with the same class of functional groups have matching polarities, whereas in a dissonant pattern, their polarities are unlike. If a consonant pattern is present in a molecule, a simple synthesis may often be achieved."