作者:Ho H. Lee、Brian D. Palmer、Maruta Boyd、William A. Denny
DOI:10.1002/jhet.5570330431
日期:1996.7
2-bromo-5-nitrothiazole (2) with weakly basic secondary aliphatic amines gives the expected 2-amino products from nucleophilic displacement of the bromine, reaction of the isomeric 5-bromo-2-nitrothiazole (3) with such amines gives mixtures of the expected 5-amino products together with 2-aminated 5-nitrothiazole rearrangement products. The identity of the latter were detemined by alternative synthesis, and by X-ray
虽然2-溴-5-硝基噻唑(2)与弱碱性仲脂肪胺反应可从溴的亲核取代反应获得预期的2-氨基产物,但异构5-溴-2-硝基噻唑(3)与此类胺反应得到预期的5-氨基产物与2-胺化的5-硝基噻唑重排产物的混合物。后者的身份通过替代合成和X射线晶体学测定衍生物确定。提出的机理是将5-溴-2-硝基噻唑(3)缓慢热异构化为反应性更高的2-溴-5-硝基异构体2 在较弱的胺亲核试剂的情况下,其与5-溴基团的直接(但缓慢)亲核取代竞争,形成正常的取代产物。