Ring-opening reactions of 1,4-diazabicyclo[2.2.2]octane (DABCO) derived quaternary ammonium salts with phenols and related nucleophiles
作者:Nenad Maraš、Slovenko Polanc、Marijan Kočevar
DOI:10.1039/c1ob06676e
日期:——
1,4-Diazabicyclo[2.2.2]octane (DABCO) has been evaluated as a starting material for the synthesis of 1-alkyl-4-(2-phenoxyethyl)piperazines and related derivatives. We found that 1-alkyl-1,4-diazabicyclo[2.2.2]octan-1-ium salts, resulting from the alkylation of DABCO, efficiently react with a variety of nucleophiles in polyethyleneglycol (PEG) or diglyme at high temperatures to give piperazine products
1,4-二氮杂双环[2.2.2]辛烷(DABCO)已被评估为合成1-烷基-4-(2-苯氧基乙基)哌嗪及其相关衍生物的原料。我们发现,由DABCO烷基化产生的1-烷基-1,4-二氮杂双环[2.2.2] octan-1-ium盐可在高温下与聚乙二醇(PEG)或二甘醇二甲醚中的多种亲核试剂有效反应,得到亲核开环反应产生的哌嗪产物。发现当使用1-苄基-1,4-二氮杂双环[2.2.2] octan-1-ium盐时,苄基化副反应与较软的亲核试剂有关,而未观察到其他类型的烷基化。一锅法可使用苯酚或其他亲核试剂和DABCO,直接从伯醇,卤代烷或磺酸盐直接合成哌嗪。