Convergent Access to Bis-spiroacetals through a Sila-Stetter–Ketalization Cascade
摘要:
An NHC-catalyzed sila-Stetter reaction between aliphatic acylsilanes and vinylketones bearing silyl ether substituents affords functionalized 1,4-diketones, which upon treatment under acidic conditions leads to the corresponding bis-spiroacetals. The two-step sequence may also be carried out in a one-pot operation leading to high yields of the desired bis-spiroacetals.
Efficient One-Step Synthesis of Bis-Spiroketals from Diynediols by π-Lewis Acid-Catalyzed Hydroalkoxylation/Hydration
作者:Ivan Volchkov、Kamlesh Sharma、Eun Jin Cho、Daesung Lee
DOI:10.1002/asia.201100131
日期:2011.8.1
Spiroling out of control: An efficientone‐stepsynthesis of 5‐5‐5, 5‐5‐6, and 6‐5‐6 bis‐spiroketals from 4,6‐diyne‐1,n‐diols and 5,7‐diyne‐1,n‐diols has been developed with good yields. A mixture of cis‐ and trans‐bis‐spiroketals were generally obtained from each substrate and the isolated cis‐ and trans‐bis‐spiroketals undergo interconversion to reach their equilibrium composition (see scheme).