Telescoped Synthesis of γ-Bromo-β-Lactones from Allylic Bromides Employing Carbon Dioxide
作者:Sreekumar Vellalath、Daniel Romo
DOI:10.1002/ijch.201600125
日期:2017.4
A direct synthesis of the title compounds involving a stepwise Zn‐mediated carboxylation of allylic bromides with CO2 delivering β, γ‐unsaturated carboxylic acids and a subsequent bromolactonization is reported. The described method demonstrates the use of readily prepared allylzinc bromides by the method of Knochel for fixation of CO2 employing commodity chemicals and zinc dust. This process was then
Selenium-Catalyzed Halolactonization: Nucleophilic Activation of Electrophilic Halogenating Reagents
作者:Shelli R. Mellegaard、Jon A. Tunge
DOI:10.1021/jo048460o
日期:2004.12.1
Diphenyl diselenide catalyzes the halolactonization of unsaturated acids with N-halosuccinimides under mild conditions. The diselenide not only accelerates the reactions, but in some cases affords regiocontrol in favor of gamma-lactone products. Experiments show that the regioselectivity in favor of gamma-lactones is a result of kinetic rather than thermodynamic control.
Synthesis of hydroxy lactones by bis(tributyltin) oxide promoted ring expansion of halo lactones