Radical-nucleophilic substitution (SRN1) reactions. Part 7. Reactions of aliphatic α-substituted nitro compounds.

Abstract

α-Nitrothiocyanates R₂C(SCN)NO₂ have been prepared by oxidative addition of thiocyanate anion to nitronate anions and undergo S_RN1 substitution reactions by loss of thiocyanate with nitronate anions, phenylsulfinate, azide and p-nitro- and p-chloro-benzenethiolates in dipolar aprotic solvents. 2-Nitro-2-thiocyanatopropane and other 2-substituted-2-nitropropanes [Me₂C(X)NO₂ with X = I, Br, Cl, NO₂, PhSO₂] react with thiolates by S_RN1 reactions and/or redox reactions to give disulfides by a polar abstraction or chain SET (S_ET2) mechanisms. The products are dependent on the nucleophilicity of the thiolates, the polarisability of the α-substituent, the solvent and the presence of light catalysis, radical traps or strong electron acceptors. 2-Substituted-2-nitropropanes [Me₂C(X)NO₂ with X = N₃, NO₂, CN, p-NO₂–C₆H₄–NN] undergo S_RN1 substitutions with thiolates by loss of nitrite. 2-Substituted-2-nitropropanes Me₂C(X)NO₂ and thiolates only yield disulfides in methanol due to solvation of the nitro groups.