Thermodynamically controlled deracemization of some acyclic ketones bearing a chiral center at the position α to the carbonyl group was satisfactorily achieved. Acyclic ketones with high optical purities could be isolated after treatment of the racemic ketones with base in aqueous MeOH in the presence of (–)-(2R,3R)-trans-2,3-bis(hydroxydiphenylmethyl)-1,4-dioxaspiro[5.4]decane (1a). The efficiency
A borane-mediated palladium-catalyzed reductive allylic alkylation of α,β-unsaturated carbonyl compounds
作者:Barry M. Trost、Zhijun Zuo、Johnathan E. Schultz、Nagaraju Anugula、Katherine A. Carr
DOI:10.1039/c9sc05970a
日期:——
generated boron enolates via tandem 1,4-hydroboration is reported. Investigation of the reaction revealed insights into specific catalyst electronic features as well as a profound leaving group effect that proved crucial for achieving efficient allylic alkylation of ester enolates at room temperature and ultimately a highly preparatively useful synthesis of notoriously challenging acyclic all-carbon quaternary
Construction of bicyclic systems containing an oxygen bridge by isomerization of cyclic epoxy alcohols
作者:Masaru Iwakura、Hiroshi Tokura、Keiji Tanino
DOI:10.1016/j.tetlet.2017.02.023
日期:2017.3
A novel method for constructing a 7-oxabicyclo[2.2.1]heptane skeleton was developed. The substrates, namely cis-3,4-epoxy-1-cyclohexanol derivatives, were prepared from the corresponding 3-cyclohexen-1-ol derivatives via a stereoselective epoxidation reaction using a vanadium catalyst. Upon heating with lithium iodide in propionitrile, the cis-epoxy alcohol was transformed into the 7-oxabicyclo[2.2