5 research outputs found

    Rh(II)-Catalyzed Reactions of Diazoesters with Organozinc Reagents

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    Rh­(II)-catalyzed reactions of diazoesters with organozinc reagents are described. Diorganozinc reagents participate in reactions with diazo compounds by two distinct, catalyst-dependent mechanisms. With bulky diisopropylethyl acetate ligands, the reaction mechanism is proposed to involve initial formation of a Rh-carbene and subsequent carbozincation to give a zinc enolate. With Rh<sub>2</sub>(OAc)<sub>4</sub>, it is proposed that initial formation of an azine precedes 1,2-addition by an organozinc reagent. This straightforward route to the hydrazone products provides a useful method for preparing chiral quaternary α-aminoesters or pyrazoles via the Paul–Knorr condensation with 1,3-diketones. Crossover and deuterium labeling experiments provide evidence for the mechanisms proposed

    Rh(II)-Catalyzed Reactions of Diazoesters with Organozinc Reagents

    No full text
    Rh­(II)-catalyzed reactions of diazoesters with organozinc reagents are described. Diorganozinc reagents participate in reactions with diazo compounds by two distinct, catalyst-dependent mechanisms. With bulky diisopropylethyl acetate ligands, the reaction mechanism is proposed to involve initial formation of a Rh-carbene and subsequent carbozincation to give a zinc enolate. With Rh<sub>2</sub>(OAc)<sub>4</sub>, it is proposed that initial formation of an azine precedes 1,2-addition by an organozinc reagent. This straightforward route to the hydrazone products provides a useful method for preparing chiral quaternary α-aminoesters or pyrazoles via the Paul–Knorr condensation with 1,3-diketones. Crossover and deuterium labeling experiments provide evidence for the mechanisms proposed

    Enantioselective Synthesis of Cyclobutanes via Sequential Rh-catalyzed Bicyclobutanation/Cu-catalyzed Homoconjugate Addition

    No full text
    Enantiomerically enriched cyclobutanes are constructed by a three-component process in which <i>t</i>-butyl (<i>E</i>)-2-diazo-5-arylpent-4-enoates are treated with Rh<sub>2</sub>(<i>S</i>-NTTL)<sub>4</sub> to provide enantiomerically enriched bicyclobutanes, which can subsequently engage in homoconjugate addition/enolate trapping sequence to give densely functionalized cyclobutanes with high diastereoselectivity. This three-component, two-catalyst procedure can be carried out in a single flask. Rh<sub>2</sub>(<i>S</i>-NTTL)<sub>4</sub>-catalyzed reaction of <i>t</i>-butyl (<i>Z</i>)-2-diazo-5-phenylpent-4-enoate gives the Büchner cyclization product in excellent enantioselectivity

    Enantioselective Synthesis of Cyclobutanes via Sequential Rh-catalyzed Bicyclobutanation/Cu-catalyzed Homoconjugate Addition

    No full text
    Enantiomerically enriched cyclobutanes are constructed by a three-component process in which <i>t</i>-butyl (<i>E</i>)-2-diazo-5-arylpent-4-enoates are treated with Rh<sub>2</sub>(<i>S</i>-NTTL)<sub>4</sub> to provide enantiomerically enriched bicyclobutanes, which can subsequently engage in homoconjugate addition/enolate trapping sequence to give densely functionalized cyclobutanes with high diastereoselectivity. This three-component, two-catalyst procedure can be carried out in a single flask. Rh<sub>2</sub>(<i>S</i>-NTTL)<sub>4</sub>-catalyzed reaction of <i>t</i>-butyl (<i>Z</i>)-2-diazo-5-phenylpent-4-enoate gives the Büchner cyclization product in excellent enantioselectivity

    Enantioselective Synthesis of Cyclobutanes via Sequential Rh-catalyzed Bicyclobutanation/Cu-catalyzed Homoconjugate Addition

    No full text
    Enantiomerically enriched cyclobutanes are constructed by a three-component process in which <i>t</i>-butyl (<i>E</i>)-2-diazo-5-arylpent-4-enoates are treated with Rh<sub>2</sub>(<i>S</i>-NTTL)<sub>4</sub> to provide enantiomerically enriched bicyclobutanes, which can subsequently engage in homoconjugate addition/enolate trapping sequence to give densely functionalized cyclobutanes with high diastereoselectivity. This three-component, two-catalyst procedure can be carried out in a single flask. Rh<sub>2</sub>(<i>S</i>-NTTL)<sub>4</sub>-catalyzed reaction of <i>t</i>-butyl (<i>Z</i>)-2-diazo-5-phenylpent-4-enoate gives the Büchner cyclization product in excellent enantioselectivity
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