A bromide salt mediated neighboring ester-participated bromocyclization of o-alkynylbenzoates is described here for synthesis of benzil-o-carboxylate. 4-bromoisocoumarins are also reached when phenyl o-alkynylbenzoate is used as the substrate. Mechanism studies suggest that the whole process is comprised by electrophilic bromocyclization and dibromohydration-based ring-opening, and the neighboring
Neighbouring Formyl Group Assisted Oxidation of o-Alkynylarenecarbaldehydes by an Iodine/Water System
作者:Karuppusamy Sakthivel、Kannupal Srinivasan
DOI:10.1002/ejoc.201001746
日期:2011.5
The oxidation of o-alkynylarenecarbaldehydes into tricarbonyl compounds by an iodine/watersystem is described. The reaction takes place via isochromenol intermediates formed by intramolecular assistance of the formylgroup. The procedure was applied to various o-alkynylarenecarbaldehydes to afford the corresponding products in good to excellent yields.
NBS-Mediated Oxygen Transfer Reaction of Carbonyl in Ester: Efficient Synthesis of Benzil-<i>o</i>
-carboxylate Derivative From <i>o</i>
-Alkynylbenzoate
diketonization. A plausible mechanism suggests that a bromo‐incoporated isocoumarin cation is described as an intermediate, and the whole process is constituted by NBS‐mediated electrophilic 6‐endo annulation and oxygen transferreaction through NBS‐mediated oxidative ring‐opening. Water serves as a nucleophile of ring‐opening.