Enantioselective conjugate addition of catalytically generated zinc homoenolate

• Main Authors: Sekiguchi, Yoshiya, Yoshikai, Naohiko
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2022
• Subjects: Science::Chemistry; Addition Reactions; Zinc Compounds
• Online Access: https://hdl.handle.net/10356/159329
• Institution: Nanyang Technological University

We report herein an enantioselective conjugate addition reaction of a zinc homoenolate, catalytically generated via ring opening of a cyclopropanol, to an α,β-unsaturated ketone. The reaction is promoted by a zinc aminoalkoxide catalyst generated from Et2Zn and a chiral β-amino alcohol to afford 1,6-diketones, which undergo, upon heating, intramolecular aldol condensation to furnish highly substituted cyclopentene derivatives with good to high enantioselectivities. The reaction has proved applicable to various 1-substituted cyclopropanols as well as chalcones and related enones. The chiral amino alcohol has proved to enable ligand-accelerated catalysis of the homoenolate generation and its conjugate addition. Positive nonlinear effects and lower reactivity of a racemic catalyst have been observed, which can be attributed to a stable and inactive heterochiral zinc aminoalkoxide dimer.