α-Hydroxy carbon radicals generated from alcohols by the action of NHPI smoothly added to electron-deficient alkynes like acetylenedicarboxylates. For instance, the reaction of 2-propanol with dimethyl acetylenedicarboxylate afforded maleate derivative 3, 3-methoxycarbonyl-4,4-dimethyl-2-buten-4-olide (4), and a fused bis-γ-butyrolactone 5 formed by further addition of 2-hydroxy-2-propyl radical to 4.
The reaction of photochemically generated α-hydroxyalkyl radicals with alkynes: a synthetic route to γ-butenolides
作者:Niall W.A. Geraghty、Elaine M. Hernon
DOI:10.1016/j.tetlet.2008.11.067
日期:2009.2
and their subsequent carbon-carbon bond forming reaction with propiolate esters and acetylenedicarboxylates, gives a mixture of a β-(hydroxyalkyl)enoate, the result of a formal cis addition, and the unsaturated lactone (γ-butenolide) resulting from the spontaneous cyclization of the corresponding trans addition product. Treatment of the cis adduct with NBS converts it to the same lactone, and so the