3-Alkoxy-2,5-dihydrofurans by Gold-Catalyzed Allenyl Cyclizations and Their Transformation into 1,4-Dicarbonyl Compounds, Cyclopentenones, and Butenolides
作者:Hans-Ulrich Reissig、Malte Brasholz、Branislav Dugovič
DOI:10.1055/s-0030-1258265
日期:2010.11
The addition of lithiated alkoxyallenes to carbonyl compounds furnishes allenyl alcohols, which undergo a highly efficient and chemoselective 5-endo-trig cyclization to 3-alkoxy-2,5-dihydrofurans catalyzed by gold(I) chloride. The dihydrofurans produced can be either oxidized to β-alkoxy butenolides by a manganese(III) acetate catalyzed radical oxidation with tert-butyl hydroperoxide, or transformed
向羰基化合物中添加锂化的烷氧基丙二烯提供了烯丙醇,其通过氯化金(I)催化高效且化学选择性的5-内-trig环化成3-烷氧基-2,5-二氢呋喃。生成的二氢呋喃可以通过乙酸锰(III)催化的叔丁基氢过氧化物氧化为β-烷氧基丁烯化物,也可以在存在DDQ的情况下通过氧化环裂解将其转化为α,β-不饱和的γ-酮醛。水。用甲醇钠在甲醇中处理γ-酮醛可促进非对映选择性分子内羟醛的加成,从而以良好收率提供烷氧基取代的环戊烯酮衍生物。 丙二烯-二氢呋喃-环戊烯酮-金催化-烯丙基氧化