Oxidative 5-<i>Endo</i> Cyclization of Enamides Mediated by Ceric Ammonium Nitrate
作者:Andrew J. Clark、Colin P. Dell、John M. McDonagh、Joanna Geden、Peter Mawdsley
DOI:10.1021/ol030045f
日期:2003.6.1
[reaction: see text] Ceric ammonium nitrate mediates the oxidative 5-endo radical-polar crossover reactions of beta-enamide esters to give 5,5-C,O-disubstituted-gamma-lactams. Trapping of the intermediate cations leads to 5-hydroxy- or 5-alkoxy-gamma-lactams depending upon the reaction conditions. The methodology was used to synthesize the basic heterocyclic ring fragments of the natural products L-755
[反应:见正文]硝酸铈铵介导β-烯酰胺酯的氧化性5-内基自由基-极性交叉反应,得到5,5-C,O-二取代-γ-内酰胺。取决于反应条件,中间阳离子的捕获导致5-羟基-或5-烷氧基-γ-内酰胺。该方法用于合成天然产物L-755,807,喹诺斯汀C和PI-091的基本杂环片段。