A novel stereoselective tin-free radical protocol for the enantioselective synthesis of pyrrolidinones and its application to the synthesis of biologically active GABA-derivatives
作者:Verónica Rodríguez-Soria、Leticia Quintero、Fernando Sartillo-Piscil
DOI:10.1016/j.tet.2008.01.063
日期:2008.3
fashion, via a sequential 5-exo-trig radical cyclization-hydrogen or bromine atom-transfer process, under non-tin conditions. Interestingly, when N-allyl-α-bromoacetamides were treated with triethylborane/MeOH(excess)/BF3·OEt2 in toluene at −78 °C, a tandem 5-exo-trig radical cyclization-hydrogen atom-transfer reaction operated, on the other hand, a tandem 5-exo-trig radical cyclization-bromine atom-transfer
光学纯的4-烷基吡咯啉-2-酮是从手性合成Ñ在高选择性和立体控制的方式-烯丙基-α-bromoacetamides,通过顺序5-外型- trig的自由基环化氢或溴原子的转移过程中,在非锡条件下。有趣的是,当N-烯丙基-α-溴乙酰胺在-78°C下用甲苯中的三乙基硼烷/ MeOH(过量)/ BF 3 ·OEt 2处理时,进行串联的5- exo - trig自由基环化-氢原子转移反应,另一方面,串联5- exo - trig当在-78°C下用等摩尔量的MeOH的THF溶液进行自由基环化-溴原子转移反应时,收率和立体选择性高。因此,通过该锡自由基途径合成了光学纯的4-烷基-吡咯啉-2-酮,并将其转化为它们相应的具有生物活性的GABA衍生物普瑞巴林和CAMP。