Visible Light-Promoted Synthesis of Spiroepoxy Chromanone Derivatives via a Tandem Oxidation/Radical Cyclization/Epoxidation Process
作者:Sungwoo Jung、Jiyun Kim、Sungwoo Hong
DOI:10.1002/adsc.201701072
日期:2017.11.23
A highly efficient and straightforward approach for the synthesis of spiroepoxy chroman‐4‐one derivatives was developed using a visible light‐enabled tandem radical strategy. The reaction is initiated by the formation of an acyl radical that undergoes intramolecularradical cyclization and epoxidation. The optimal result was obtained with 1 mol% of Ru(bpy)3Cl2⋅6H2O, TBHP, and K2CO3 in i‐PrOAc at room
使用可见光启用的串联自由基策略开发了一种高效且直接的合成螺环氧基苯并吡喃-4-酮衍生物的方法。通过形成经历分子内自由基环化和环氧化的酰基自由基来引发反应。用1mol%的Ru获得的最优结果(BPY)3氯2 ⋅6H 2 O,TBHP,和K 2 CO 3在我-PrOAc在室温下与来自蓝色LED照射。这种前所未有的串联方法利用了广泛的底物,并提供了一种方便而强大的合成工具,可用于获得合成上有用的螺环苯并二氢吡喃-4-酮及其含氮衍生物。
Visible-light induced cascade radical cyclization of sulfinic acids and o-(allyloxy)arylaldehydes towards functionalized chroman-4-ones
Abstract An efficient method for the synthesis of functionalized chroman-4-ones induced by visible light via the radical cyclization reaction of sulfinic acids and o-(allyloxy)arylaldehydes at room temperature was described. The corresponding products were isolated with moderate to good yields. Radical mechanism was proposed for this transformation. Anti-microbial activity of some desired compounds
Photoinduced Free Radical Chemistry of the Acyl Tellurides: Generation, Inter- and Intramolecular Trapping, and ESR Spectroscopic Identification of Acyl Radicals
作者:David Crich、Chen Chen、Jae-Taeg Hwang、Hongwei Yuan、Aristotle Papadatos、Robert I. Walter
DOI:10.1021/ja00099a011
日期:1994.10
Acyl tellurides are prepared in good to excellent yield by the reaction of sodium aryl tellurides with acyl chlorides, or mixed anhydrides, and are found to be moderately air-stable substances. In contrast to previous literature reports, acyl tellurides of aryl and vinyl carboxylic acids are found to be excellent sources of acyl radicals on photolysis with a simple white light source. The acyl radicals so generated may be trapped intermolecularly by dichalcogenides, or by TEMPO in excellent yield. Trapping by N-tert-butyl-alpha-phenyl nitrone produces a stable nitroxide radical which has been characterized by ESR spectroscopy. The very efficient trapping of acyl radicals by acyl tellurides themselves is demonstrated by a crossover experiment. Acyl tellurides are shown to participate in very efficient radical cyclization reactions onto alkenes with the formation of five-, six-, and eight-membered rings. The immediate products of the cyclizations onto alkenes are alpha-[(aryltelluro)methyl] ketones and the chemistry of these relatively unstable species is briefly described. Treatment with hydrogen peroxide affords alpha-methylene ketones in high yield. When elimination of the aryl telluro group is not possible the alpha-[(aryltelluro)methyl] ketones are stable species that may subsequently be employed in further radical chain reactions, for example with tributyltin hydride and methyl acrylate. Cyclization onto alkynes yields alpha-[(aryltelluro)methylene] ketones which are stable species and which take part in substitution reactions with higher order cuprates or with diphenyl diselenide.