Selective Dealkylations of Aryl Alkyl Ethers, Thioethers, and Selenoethers

Synthetically useful methods to effect the selective dealkylation of aryl alkyl ethers, thioethers, and selenoethers are presented and discussed. These reactions can be effected by nucleophilic aliphatic substitution, by elimination and by electron-transfer. Ethers, thioethers, and selenoethers react with rates that are sufficiently different, such that with the appropriate choice of reactant it is possible to effect the removal of the desired alkyl group in polyfunctional molecules of the type Ar(XR¹)XR² or Ar(XR¹)YR², where X and Y are O, S or Se, and R¹ and R² are two equal or different alkyl groups. Polydealkylation reactions are also possible in some cases. 1. Introduction 2. Methods of Dealkylation 2.1. Substitution Reactions 2.2. Elimination Reactions 2.3. Electron-Transfer Reactions 3. Monodealkylation Reactions of ArXR and Ar(XR¹)XR² 3.1. Phenols and (Alkoxy)phenols 3.2. Thiophenols and (Alkylthio)thiophenols 3.3. Selenophenols and (Alkylseleno)selenophenols 4. Monodealkylation Reactions of Ar(XR¹)YR² 4.1. (Alkoxy)thiophenols and (Alkylthio)phenols 4.2. (Alkoxy)selenophenols and (Alkylseleno)phenols 4.3. (Alkylthio)selenophenols and (Alkylseleno)thiophenols 5. Polydealkylation Reactions 5.1. Poly(mercapto)arenes and Poly(hydroseleno)arenes 5.2. (Hydroseleno)thiophenols 5.3. Mercaptophenols 5.4. Aryl Thiocyanates 6. Concluding Remark