Organocatalytic Redox Isomerization of Electron-Deficient Allylic Alcohols: Synthesis of 1,4-Ketoaldehydes
作者:Keshab Mondal、Buddhadeb Mondal、Subhas Chandra Pan
DOI:10.1021/acs.joc.6b00243
日期:2016.6.3
An organocatalytic redox isomerization strategy has been developed for the synthesis of 1,4-ketoaldehydes. DABCO was found to be the best catalyst for the isomerization of γ-hydroxy enones. With 20 mol % of DABCO as catalyst and DMSO as the solvent high yields have been achieved for different 1,4-ketoaldehydes.
A new transition-metal-free reductive deoxygenative olefination of phosphorus ylides with CO2, an abundant and sustainable C1 chemical feedstock, is described. This catalytic CO2 fixation afforded β-unsubstituted acrylates and vinyl ketones in good yields with broad scope and good functional group tolerance under mild reaction conditions. Cost-effective and easily handled polymethylhydrosiloxane was
pyridine-boronyl radical catalyzed intramolecular ring expansions. This metal-free radical pathway harnesses readily available catalysts and unactivated vinylcyclopropane starting materials, providing an array of cyclopentene derivatives chemoselectively under relatively mild conditions. Mechanistic studies support the idea that the boronyl radical engages in the generation of allylic/ketyl radical species