Mild and Ligand-Free Pd(II)-Catalyzed Conjugate Additions to Hindered γ-Substituted Cyclohexenones
摘要:
Ligand-free cationic Pd(II) catalyst with NaNO3 as an additive is a highly active catalytic system for conjugate additions to sterically hindered gamma-substituted cyclohexenones. More challenging gamma gamma- and beta gamma-substrates also react well to produce products with quaternary centers in good dr. The conjugate additions occur in a diastereoselective fashion under mild, practical and air-stable conditions, using readily available commercial reagents.
Osmium-Promoted Electrophilic Substitution of Anisoles: A Versatile New Method for the Incorporation of Carbon Substituents
作者:Stanley P. Kolis、Michael E. Kopach、Ronggang Liu、W. Dean Harman
DOI:10.1021/jo961983e
日期:1997.1.1
A structurally and electronically diverse set of anisoles are dihapto-coordinated to the pi-base pentaammineosmium(II) and treated with a variety of carbon electrophiles (e.g. Michael accepters, acetals). After deprotonation of a 4H-anisolium intermediate with a tertiary amine base, C(4)-substituted anisole complexes are isolated. The functionalized arenes are removed from the metal center either by mild heating or treatment with an oxidant (e.g. AgOTf, DDQ, CAN). The resulting substituted anisoles are isolated with yields ranging from 55-95%.
Mild and Ligand-Free Pd(II)-Catalyzed Conjugate Additions to Hindered γ-Substituted Cyclohexenones
作者:James A. Jordan-Hore、James N. Sanderson、Ai-Lan Lee
DOI:10.1021/ol300794a
日期:2012.5.18
Ligand-free cationic Pd(II) catalyst with NaNO3 as an additive is a highly active catalytic system for conjugate additions to sterically hindered gamma-substituted cyclohexenones. More challenging gamma gamma- and beta gamma-substrates also react well to produce products with quaternary centers in good dr. The conjugate additions occur in a diastereoselective fashion under mild, practical and air-stable conditions, using readily available commercial reagents.