Stereodivergent organocatalytic intramolecular michael addition/ lactonization for the asymmetric synthesis of substituted dihydrobenzofurans and tetrahydrofurans

The authors thank the Royal Society for a University Research Fellowship (A.D.S.), the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007–2013), ERC Grant Agreement No. 279850 (A.D.L.H. and J.E.T.), and the EPSRC (DTA studentship to D.B.) for funding.A stereodivergent asymmetric Lewis base catalyzed Michael addition/lactonization of enone acids into substituted dihydrobenzofuran and tetrahydrofuran derivatives is reported. Commercially available (S)-(-)-tetramisole hydrochloride gives products with high syn diastereoselectivity in excellent enantioselectivity (up to 99:1 d.r. , 99% ee), whereas using a cinchona alkaloid derived catalyst gives the corresponding anti-diastereoisomers as the major product (up to 10:90 d.r., 99% ee). You can have it both ways! A stereodivergent asymmetric Lewis base catalyzed Michael addition/lactonization of enone acids into substituted dihydrobenzofuran and tetrahydrofuran derivatives is reported, giving products with high d.r. and ee (see scheme).Publisher PDFPeer reviewe

Asymmetric Michael Addition-Lactonization of Carboxylic Acids

A highly efficient asymmetric intra- and intermolecular Michael addition-lactonization of a variety of enone acids, arylacetic acids, and α-keto-β,γ-unsaturated esters using chiral isothioureas as catalysts was reported. The combination of an activating agent and the catalyst was crucial to generate an efficient catalytic cycle. To further demonstrate the utility of this process, the authors performed a simple derivatization of the products to obtain indene carboxylates in good yields and high enantioselectivities

Stereodivergent organocatalytic intramolecular michael addition/ lactonization for the asymmetric synthesis of substituted dihydrobenzofurans and tetrahydrofurans

A stereodivergent asymmetric Lewis base catalyzed Michael addition/lactonization of enone acids into substituted dihydrobenzofuran and tetrahydrofuran derivatives is reported. Commercially available (S)-(-)-tetramisole hydrochloride gives products with high syn diastereoselectivity in excellent enantioselectivity (up to 99:1 d.r. , 99% ee), whereas using a cinchona alkaloid derived catalyst gives the corresponding anti-diastereoisomers as the major product (up to 10:90 d.r., 99% ee). You can have it both ways! A stereodivergent asymmetric Lewis base catalyzed Michael addition/lactonization of enone acids into substituted dihydrobenzofuran and tetrahydrofuran derivatives is reported, giving products with high d.r. and ee (see scheme)

Organocatalytic Functionalization of Carboxylic Acids: Isothiourea-Catalyzed Asymmetric Intra- and Intermolecular Michael Addition−Lactonizations

Tetramisole promotes the catalytic asymmetric intramolecular Michael addition−lactonization of a variety of enone acids, giving carbo- and heterocyclic products with high diastereo- and enantiocontrol (up to 99:1 dr, up to 99% ee) that are readily derivatized to afford functionalized indene and dihydrobenzofuran carboxylates. Chiral isothioureas also promote the catalytic asymmetric intermolecular Michael addition−lactonization of arylacetic acids and α-keto-β,γ-unsaturated esters, giving anti-dihydropyranones with high diastereo- and enantiocontrol (up to 98:2 dr, up to 99% ee)

Telescoped Synthesis of Stereodefined Pyrrolidines

Telescoped and one-pot olefination/asymmetric functionalization approaches to disubstituted pyrrolidines (dr up to 99:1, up to 99% ee) have been developed using commercially available tetramisole (0.1 to 5 mol %). Using OTMS-quinidine as the Lewis base gives preferential access to an <i>anti</i>-configured pyrrolidine in high enantioselectivity

Organocatalytic Functionalization of Carboxylic Acids: Isothiourea-Catalyzed Asymmetric Intra- and Intermolecular Michael Addition−Lactonizations

Tetramisole promotes the catalytic asymmetric intramolecular Michael addition−lactonization of a variety of enone acids, giving carbo- and heterocyclic products with high diastereo- and enantiocontrol (up to 99:1 dr, up to 99% ee) that are readily derivatized to afford functionalized indene and dihydrobenzofuran carboxylates. Chiral isothioureas also promote the catalytic asymmetric intermolecular Michael addition−lactonization of arylacetic acids and α-keto-β,γ-unsaturated esters, giving anti-dihydropyranones with high diastereo- and enantiocontrol (up to 98:2 dr, up to 99% ee)

Organocatalytic Functionalization of Carboxylic Acids: Isothiourea-Catalyzed Asymmetric Intra- and Intermolecular Michael Addition−Lactonizations

Tetramisole promotes the catalytic asymmetric intramolecular Michael addition−lactonization of a variety of enone acids, giving carbo- and heterocyclic products with high diastereo- and enantiocontrol (up to 99:1 dr, up to 99% ee) that are readily derivatized to afford functionalized indene and dihydrobenzofuran carboxylates. Chiral isothioureas also promote the catalytic asymmetric intermolecular Michael addition−lactonization of arylacetic acids and α-keto-β,γ-unsaturated esters, giving anti-dihydropyranones with high diastereo- and enantiocontrol (up to 98:2 dr, up to 99% ee)

Organocatalytic Functionalization of Carboxylic Acids: Isothiourea-Catalyzed Asymmetric Intra- and Intermolecular Michael Addition−Lactonizations

Tetramisole promotes the catalytic asymmetric intramolecular Michael addition−lactonization of a variety of enone acids, giving carbo- and heterocyclic products with high diastereo- and enantiocontrol (up to 99:1 dr, up to 99% ee) that are readily derivatized to afford functionalized indene and dihydrobenzofuran carboxylates. Chiral isothioureas also promote the catalytic asymmetric intermolecular Michael addition−lactonization of arylacetic acids and α-keto-β,γ-unsaturated esters, giving anti-dihydropyranones with high diastereo- and enantiocontrol (up to 98:2 dr, up to 99% ee)