A solution of hydrogen bromide (HBr) in 1,4-dioxane was prepared and investigated for its ability to brominate alcohols, and hydrobrominate alkenes. This study revealed that the brominating ability of this HBr/1,4-dioxane solution is equal or superior to that of hydrobromic acid or HBr in acetic acid. The solution of HBr in 1,4-dioxane is robust, exhibiting no decomposition of the solvent, and retaining
ZrCl<sub>4</sub> as an Efficient Catalyst for a Novel One-Pot Protection/Deprotection Synthetic Methodology
作者:Surendra Singh、Colm D. Duffy、Syed Tasadaque A. Shah、Patrick J. Guiry
DOI:10.1021/jo800932t
日期:2008.8.1
found to be an efficientcatalyst for the one-pot esterification and deprotection of (5S,6R)-5,6-diacetoxyoct-7-enoic acid in good yields (44−62%) with a lactone formed as a minor byproduct. ZrCl4 (10−20 mol %) was also sufficient to deprotect 1,3-dioxalane, bis-TBDMS ethers, and diacetate functional groups in excellent yields of up to 93%. ZrCl4 (1−10 mol %) also promoted diol protection as the acetonide