Solvent-free double aza-Michael under ultrasound irradiation: diastereoselective sequential one-pot synthesis of pyrrolidine Lobelia alkaloids analogues
作者:Zacharias Amara、Emmanuelle Drège、Claire Troufflard、Pascal Retailleau、Delphine Joseph
DOI:10.1039/c2ob25963j
日期:——
Novel 2,5-meso-pyrrolidines have been straightforwardly synthesized from readily available symmetrical double Michael acceptors. The key step rested on an aza-Michael addition of primary alkylamines to bis-enones. Competitive Rauhut–Currier and aza-Michael reactions have been highlighted in protic solvent. Ultrasound activation associated with solvent-free conditions led to the expected pyrrolidines in quantitative yields and excellent stereoselectivities. The optimized conditions have been extended to the sonochemical synthesis of pyrrolidine Lobelia alkaloids analogues in short sequences.
新颖的 2,5-甲磺酰基吡咯烷是用容易获得的对称双迈克尔受体直接合成的。关键步骤是将伯烷基胺与双烯酮进行杂-迈克尔加成反应。Rauhut-Currier 和 aza-Michael 反应在质子溶剂中具有很强的竞争性。在无溶剂条件下进行超声波活化,可以获得预期的吡咯烷类化合物,产量高,立体选择性好。优化后的条件已扩展到短序列吡咯烷洛贝生物碱类似物的超声化学合成。