Divergent role of PIDA and PIFA in the AlX₃ (X = Cl, Br) halogenation of 2-naphthol: a mechanistic study

• Kevin A. Juárez-Ornelas,
• Manuel Solís-Hernández,
• Pedro Navarro-Santos,
• J. Oscar C. Jiménez-Halla and
• César R. Solorio-Alvarado

Beilstein J. Org. Chem. 2024, 20, 1580–1589, doi:10.3762/bjoc.20.141

• mixing PIDA with aluminum bromide, the reaction occurred with an unexpectedly higher yield (93%) than with PIFA. Therefore, the bromination reaction proceeded in the presence of PIDA/AlBr3 as a brominating system using MeCN as solvent (Scheme 3). In light of the relevance of this newly discovered

• of 2-naphthol using one equivalent of PIDA and two equivalents of aluminum bromide is shown in Scheme 5. PIDA coordinates the first equivalent of aluminum bromide to form the adduct PIDA–AlBr3, which spontaneously dissociates, giving ion pair I-1–Br. Next, via TS1–Br, complex AcO–AlBr2 is released

• with subsequent formation of intermediate I-2–Br. Then, the second equivalent of aluminum bromide coordinates to an acetate ligand, forming adduct I-3–Br, which is the brominating species. At this point, 2-naphthol reacts and forms I-4–Br via TS2–Br. Afterwards, the second equivalent of the AcO–AlBr2

AlBr₃-Promoted stereoselective anti-hydroarylation of the acetylene bond in 3-arylpropynenitriles by electron-rich arenes: synthesis of 3,3-diarylpropenenitriles

• Yelizaveta Gorbunova,
• Dmitry S. Ryabukhin and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2663–2667, doi:10.3762/bjoc.17.180

• , benzene and its polymethylated derivatives) under the action of aluminum bromide (AlBr3, 6 equiv) at room temperature for 0.5–2 h result in the stereoselective formation of 3,3-diarylpropenenitriles (Ar(Ar′)C=CHCN) in yields of 20–64%, as products of mainly anti-hydroarylation of the acetylene bond. The

• obtained 3,3-diarylpropenenitriles in triflic acid CF3SO3H (TfOH) at room temperature for 1 h are cyclized into 3-arylindenones in yields of 55–70%. Keywords: aluminum bromide; hydroarylation; indenones; propenenitriles; propynenitriles; Introduction Conjugated acetylene nitriles (propynenitriles, R–C≡C

• [17]. Conclusion We have developed a novel transition-metal (Pd, Pt, Rh, etc.)-free procedure for the regio- and stereoselective hydroarylation of the carbon–carbon triple bond in 3-arylpropynenitriles by arenes under electrophilic activation by aluminum bromide AlBr3. The obtained 3,3