Guiding a divergent reaction by photochemical control: bichromatic selective access to levulinates and butenolides
作者:Revannath L. Sutar、Saumik Sen、Or Eivgi、Gal Segalovich、Igor Schapiro、Ofer Reany、N. Gabriel Lemcoff
DOI:10.1039/c7sc05094a
日期:——
irradiation initiates E–Z isomerization of the carbon–carbon double bond, followed by one of two competing processes; namely, cyclization by transesterification or a 1,5-H shift and tautomerization. Quantum chemical calculations demonstrate that intermediates are strongly blue-shifted for the cyclization while red-shifted for the 1,5-H shift reaction. Hence, delaying the double bond migration by employing
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
Copper-Catalyzed Aerobic CC Bond Cleavage of Lactols with N-Hydroxy Phthalimide for Synthesis of Lactones
作者:Ya Lin Tnay、Shunsuke Chiba
DOI:10.1002/asia.201403196
日期:2015.4
The transformation of cyclichemiacetals (lactols) into lactones has been achieved by Cu‐catalyzed aerobic CC bond cleavage in the presence of N‐hydroxy phthalimide (NHPI). The present process is composed of a multistep sequence including a) formation of exo‐cyclic enol ethers by dehydration; b) addition of phthalimide N‐oxyl radical to the enol ethers followed by trapping of the resulting C‐radicals
A new method for the preparation of 3,5-disubstituted butenolides
作者:Stephen L. Buchwald、Qun Fang、Susan M. King
DOI:10.1016/0040-4039(88)85185-2
日期:1988.1
A convenient method for the transformation of suitably protected propargyl alcohols into 3,5disubstiuted butenolides has been developed. This organozirconium-based method transforms optically active propargyl alcohols into the corresponding butenolides with no loss of optical activity.