Enantioselective Synthesis of an All-Carbon Quaternary Stereocenter by Chiral Brønsted Acid-Catalyzed Friedel–Crafts-Type Reaction between Pyrroles and 3‑Indolylmethanols

We have developed a chiral phosphoric acid-catalyzed enantioselective Friedel–Crafts alkylation reaction between pyrroles and indolylmethanols. Wide substrate scope was observed, and a chiral all-carbon quaternary center was constructed at the 3 position of indoles in high yields with high to excellent enantioselectivities (up to 99% ee)

κ³(<i>P</i>,<i>C</i>,<i>C</i>)‑Allylphosphane Iridium(III) and Rhodium(III) Complexes: Preparation and Reactivity toward Nucleophilic Reagents

The first allylphosphane iridium complexes [IrCl₂(η⁵-C₅Me₅)­{κ­(<i>P</i>)-R₂PCH₂CHCH₂}] (R = <i>i</i>Pr (<b>1a</b>), Ph (<b>1b</b>)) have been synthesized by the reaction of the dimeric complex [IrCl­(μ-Cl)­(η⁵-C₅Me₅)]₂ with allyldiisopropylphosphane (ADIP) and allyldiphenylphosphane (ADPP), respectively. The cationic complex [IrCl­(η⁵-C₅Me₅)­{κ³(<i>P</i>,<i>C</i>,<i>C</i>)-<i>i</i>Pr₂PCH₂CHCH₂}]⁺ (<b>3</b>^<b>+</b>) has been prepared by the reaction of complex <b>1a</b> with NaX (X = BPh₄, PF₆) in dichloromethane. The complex <b>3⁺</b> reacts with phosphanes and alkanethiolates to give the uncommon cationic complexes [IrCl­(η⁵-C₅Me₅)­{κ²(<i>P</i>,<i>C</i>)-<i>i</i>Pr₂PCH₂CH­(PR₂R′)­CH₂}]⁺ (<b>5</b>^<b>+</b>–<b>7</b>⁺) and IrCl­(η⁵-C₅Me₅)­{κ³(<i>P</i>,<i>C,S</i>)-<i>i</i>Pr₂PCH₂CH­(SR)­CH₂}]⁺ (<b>13</b>^<b>+</b> and <b>14</b>^<b>+</b>) by chemo- and regioselective addition of the nucleophiles to the π-olefin system. The reaction of <b>1a</b> with LiBHEt₃ gives the neutral complex [IrCl­(η⁵-C₅Me₅)­{κ²(<i>P</i>,<i>C</i>)-<i>i</i>Pr₂PCH₂CH₂CH₂}] (<b>10</b>). For comparative purposes, the synthesis of the complex [RhCl­(η⁵-C₅Me₅)­{κ³(<i>P</i>,<i>C</i>,<i>C</i>)-<i>i</i>Pr₂PCH₂CHCH₂}]⁺ (<b>4</b>^<b>+</b>) and its reactivity with phosphanes, hydride, and thiolates has been also assayed

κ³(<i>P</i>,<i>C</i>,<i>C</i>)‑Allylphosphane Iridium(III) and Rhodium(III) Complexes: Preparation and Reactivity toward Nucleophilic Reagents

The first allylphosphane iridium complexes [IrCl₂(η⁵-C₅Me₅)­{κ­(<i>P</i>)-R₂PCH₂CHCH₂}] (R = <i>i</i>Pr (<b>1a</b>), Ph (<b>1b</b>)) have been synthesized by the reaction of the dimeric complex [IrCl­(μ-Cl)­(η⁵-C₅Me₅)]₂ with allyldiisopropylphosphane (ADIP) and allyldiphenylphosphane (ADPP), respectively. The cationic complex [IrCl­(η⁵-C₅Me₅)­{κ³(<i>P</i>,<i>C</i>,<i>C</i>)-<i>i</i>Pr₂PCH₂CHCH₂}]⁺ (<b>3</b>^<b>+</b>) has been prepared by the reaction of complex <b>1a</b> with NaX (X = BPh₄, PF₆) in dichloromethane. The complex <b>3⁺</b> reacts with phosphanes and alkanethiolates to give the uncommon cationic complexes [IrCl­(η⁵-C₅Me₅)­{κ²(<i>P</i>,<i>C</i>)-<i>i</i>Pr₂PCH₂CH­(PR₂R′)­CH₂}]⁺ (<b>5</b>^<b>+</b>–<b>7</b>⁺) and IrCl­(η⁵-C₅Me₅)­{κ³(<i>P</i>,<i>C,S</i>)-<i>i</i>Pr₂PCH₂CH­(SR)­CH₂}]⁺ (<b>13</b>^<b>+</b> and <b>14</b>^<b>+</b>) by chemo- and regioselective addition of the nucleophiles to the π-olefin system. The reaction of <b>1a</b> with LiBHEt₃ gives the neutral complex [IrCl­(η⁵-C₅Me₅)­{κ²(<i>P</i>,<i>C</i>)-<i>i</i>Pr₂PCH₂CH₂CH₂}] (<b>10</b>). For comparative purposes, the synthesis of the complex [RhCl­(η⁵-C₅Me₅)­{κ³(<i>P</i>,<i>C</i>,<i>C</i>)-<i>i</i>Pr₂PCH₂CHCH₂}]⁺ (<b>4</b>^<b>+</b>) and its reactivity with phosphanes, hydride, and thiolates has been also assayed