Facile Synthesis of 3-Arylindenes by HMPA-Promoted Direct Arylation of Indenes with Aryl Fluorides

Abstract

A rapid and efficient approach to 3-arylated indenes by reactions of indenes with unactivated fluoroarenes with the assistance of lithium diisopropylamide and hexamethylphosphoramide at room temperature was developed.

Hydroarylation of Alkenes by Protonation/Friedel–Crafts Trapping: HFIP-Mediated Access to Per-aryl Quaternary Stereocenters

“…Isolated as a clear oil (71 mg, 0.37 mmol, 74%): 1 H NMR (400 MHz, chloroform- d ) δ 7.64–7.59 (m, 3H), 7.55 (dt, J = 7.2, 1.0 Hz, 1H), 7.49–7.44 (m, 2H), 7.41–7.31 (m, 2H), 7.29–7.24 (m, 1H), 6.59 (t, J = 2.2 Hz, 1H), 3.52 (d, J = 2.2 Hz, 2H). Data are in agreement with those in the literature …”

“…Isolated as a white solid (118.7 mg, 0.415 mmol, 83%): mp 82 °C; 1 H NMR (400 MHz, chloroform-d) δ 7.44 (d, J = 8.5 Hz, 1H), 6.58 (d, J = 8.5 Hz, 1H), 6.14−5.98 (d, J = 1.9 Hz, 1H), 3.83 (s, 3H), 3.23−3.11 (t, J = 2.1 Hz, 2H), 2.29 (app q, J = 1.9 Hz, 3H); 13 3-Phenyl-1H-indene. 64 Following the general procedure 1. Isolated as a clear oil (71 mg, 0.37 mmol, 74%): 1 H NMR (400 MHz, chloroform-d) δ 7.64−7.59 (m, 3H), 7.55 (dt, J = 7.2, 1.0 Hz, 1H), 7.49−7.44 (m, 2H), 7.41−7.31 (m, 2H), 7.29−7.24 (m, 1H), 6.59 (t, J = 2.2 Hz, 1H), 3.52 (d, J = 2.2 Hz, 2H).…”

“…Data are in agreement with those in the literature. 64 General Procedure 2: Organocatalytic Hydroarylation. Alkene (0.1 mmol, 1 equiv) was weighed into a regular 2 mL glass vial.…”

Recent Advances in the Synthesis of Indenes

“…Many methods exist for the direct 3-arylation or 3-alkylation of indenes. Recently, Cao's group [69] has reported on a rapid and efficient approach to 3-arylated indenes 163 by reaction of indenes 162 with unactivated electron-rich fluoroarenes in the presence of lithium diisopropylamide (LDA) and hexamethylphosphoramide (HMPA) at room temperature (Scheme 65). Of course, given the mechanism involved, mixtures of isomers are obtained depending on the substitution of the fluoroarene.…”

Palladium‐Catalyzed Direct C−H Olefination of Polyfluoroarenes with Alkenyl Tosylates

“…[11] The regioselectivity shortcoming on the cleavage of para-(50 %) and meta-CÀ F bond (4 %) was observed. Metal-free alkenylation of polyfluoroarenes with indene [12] and borane-induced cyclization of arylallenes [13] were shown to give olefinated polyfluoroarene. However, the regioselectivity of the cyclization remains problematic.…”