The influence of α-coordinating groups of aldehydes on <i>E</i>/<i>Z</i>-selectivity and the use of quaternary ammonium counter ions for enhanced <i>E</i>-selectivity in the Julia–Kocienski reaction
Modified reaction conditions for improved E-selectivity of olefins in the Julia–Kocienski reaction of aldehydes having α-coordinating substituents are demonstrated. The chelating groups in aldehydes are expected to stabilize the syn-transition state with metal ions, whereas the weakly coordinating quaternary ammonium ions are devoid of all possible chelating interactions to enhance E-selectivity. A
An improved stereoselective total synthesis of (R)-rugulactone
作者:Abhishek Goswami、Partha Pratim Saikia、Bishwajit Saikia、Devdutt Chaturvedi、Nabin C. Barua
DOI:10.1016/j.tetlet.2011.07.109
日期:2011.10
A novel route for the stereoselectivetotalsynthesis of (R)-rugulactone 1 has been developed, starting from substituted epoxide 4 and 3-phenylpropionaldehyde 5 employing Julia-Kocienski olefination as a key step to construct E-configured α,β-unsaturated keto-group. The overall yield of the synthesized rugulactone is 19.94% and is better than the reported methods.