Regiodivergent Aromatic Electrophilic Substitution Using Nitrosoarenes in Hexafluoroisopropanol: A Gateway for Diarylamines andp‐Iminoquinones Synthesis

Abstract

A metal-free aromatic electrophilic substitution reaction using nitrosoarenes as the electrophile in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) is reported. HFIP activates nitrosoarene towards the electrophilic CÀ H amination followed by a concomitant NÀ O bond cleavage to deliver diarylamines without requiring any extra reagent or further treatment. The dual electrophilic nature of nitrosoarene permits a switchover of selectivity to CÀ H oxygenation furnishing dearomatizedp-iminoquinones following a unique mechanistic rationale of two consecutive [2,3] sigmatropic rearrangement in nitroso-chemistry. Scheme 4. Synthetic application of the developed methodology: Reduction of p-iminoquinones (top); one-pot sequential synthesis of diarylamines and p-iminoquinones (bottom).Scheme 5. a) 1 H NMR experiment for the activation of nitrosobenzene in HFIP. b) Plausible mechanism for CÀ H amination. Scheme 6. a) Mechanistic proposal for the formation of p-iminoquinone via two consecutive [2,3] sigmatropic rearrangement. b) An alternative mechanism for the formation of p-iminoquinone. c) An alternative mechanism for the nitrone formation.

Nitrosobenzene‐Enabled Chiral Phosphoric Acid Catalyzed Enantioselective Construction of Atropisomeric N‐Arylbenzimidazoles

“…Dehydration of thus-formed intermediate A releases a vicinal diimine intermediate B which has been identified in similar transformations. [14] As confirmed by control experiments (Scheme…”

HFIP in Organic Synthesis

“…Diarylamines or p -iminoquinones were synthesized through C–H bond functionalization of electron-rich arenes using nitrosoarenes as a dual electrophile in HFIP (Scheme ). HFIP was found to be critical in promoting this aromatic electrophilic substitution (S E Ar) reaction as other solvents including TFE, MeCN, EtOH, THF, and MeNO 2 gave little to no conversion of the desired products. Two modes of nitrosoarene activation by HFIP were proposed (Scheme a).…”

Aggregation in Aqueous Solutions of 2-(Tetrafluoro(trifluoromethyl)-λ6-sulfanyl-ethan-1-ol (CF3SF4-ethanol)): A Comparison with Aqueous Trifluoroethanol and Hexafluoroisopropanol Using Molecular Dynamics Simulations and Dynamic Light Scattering Experiments

“…Many of the novel effects of aqueous solutions of fluorinated alcohols, such as 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), arise from the large ionization constants, induced dipole interactions, polarity, and lipophilicity of these compounds. , Fluorinated alcohols have extensive biological, agricultural, industrial, and chemical applications. − Aqueous solutions of fluorinated alcohols have found widespread utility in synthetic reactions, solvolytic experiments, and protein structure analysis studies. , Unfortunately, the chemical and thermal stability of the fluorinated alcohols can result in undesirable environmental and biological accumulation.…”