ELECTROPHILIC ATTACK ON RING HETEROATOMS

Electrophilic attack on ring heteroatoms ties up an electron pair (which may have been engaged in resonance in the parent species) and confers positive charge on the system, thereby inviting nucleophilic attack or elimination reactions to follow. In small systems the primary product is usually quite unstable. Nucleophilic attack on protonated or Lewis acid-coordinated species will be treated below (Section 5.2.7), because it is not always clear whether such reactions are preceded by an electrophilic step (e.g. protonation) or not. 

Reactions of this type are rare for reasons discussed in Section 3.3.1.4. No examples are known of electrophilic attack at the furan oxygen atom. 

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Electrophilic Attack on Ring Heteroatom 5.14.3.2.1 Protonation and basicity... 

Electrophilic Attack on Ring Heteroatoms 5.15.2.2.1 1,2-Diazetidine derivatives... 

Electrophilic Attack on Ring Heteroatoms (see also Section 3.5.7.2)... 

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