作者:Markus Bergauer、Peter Gmeiner
DOI:10.1055/s-2001-18445
日期:——
Treatment of the acceptor-substituted pyrroles 1a-k with neat triethyl orthoformate gives access to the diethoxymethyl (DEM) protected derivatives 2a-k in high yield. Convenient and mild cleavage was achieved by subsequent treatment of the DEM-pyrroles 2a-k with trifluoroacetic acid in acetonitrile and aqueous NaOH at room temperature. DEM protection proved suitable for a variety of regioselective transformations involving directed ortho-metalation and iodine-magnesium exchange processes. Furthermore, electrophilic halogenations and Pd-catalyzed coupling reactions were also carried out.
对取代的吡咯化合物1a-k进行无水三乙基邻甲酸酯处理,可以高产率地得到二乙氧基甲基(DEM)保护衍生物2a-k。随后用三氟乙酸和乙腈以及水溶性氢氧化钠在室温下处理DEM-吡咯化合物2a-k,可以方便而温和地裂解。DEM保护适用于涉及定向邻位金属化和碘-镁交换过程的多种区域选择性转化。此外,还进行了电负性卤化反应和钯催化的偶联反应。