Catalytic Asymmetric Benzoin Condensation for the Synthesis of Natural Products and Their Analogs
Hikaru Abe1, Kazushige Sasaki1, Chiharu Sakashita1
1Institute of Microbial Chemistry (BIKAKEN), Tokyo, 3-14-23 Kamiosaki Shinagawa-ku, Tokyo, 141-0021, Japan.
Abstract:
Catalytic enantioselective benzoin condensation conditions that are potentially useful for the total synthesis of cycloimidamicins and structure-activity relationship studies of these natural products were developed. A triazole-based NHC catalyst promoted the transformation to afford the cyclization products. To make the reactions applicable to substrates with complex structural features, a Lewis acidic additive, B(OMe)Et2, was used, but fine-tuning of the base and solvent conditions was required to attain a good chemical yield and excellent enantioselectivity. These conditions showed a broad substrate scope and were not limited to substrates useful for the synthesis of cycloimidamicins and their related compounds. This study also clearly demonstrates the utility of N-heterocyclic carbene organocatalysts that have not been reported to exhibit perfect enantioselectivity in intramolecular benzoin condensation.
More Related Videos
06:31Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators
Published on: November 27, 2015
10:17Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Related Concept Videos
Ketones with Nonenolizable Aromatic Aldehydes: Claisen–Schmidt Condensation
As the self-condensation of ketones is generally not favored in basic conditions, the self-condensed products do not form in the reaction between ketones and benzaldehyde. The general reaction of Claisen–Schmidt...
Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
Electrophilic Aromatic Substitution: Sulfonation of Benzene
Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism
Aromatic Compounds: Overview
In 1825, Faraday isolated...
