Novel Use of <i>N</i>-Carboalkoxy α,β-Unsaturated Iminium Ions as Dienophiles in Diels-Alder Reactions
作者:Margaret Brimble、Patrick O’Connor、Karsten Körber
DOI:10.1055/s-2008-1072658
日期:——
Tricyclic spiro- N, O-acetals have been assembled in a single step by cycloaddition of hydroxymethyl-substituted dienes to iminium ion activated dienophiles that were generated by acidolysis of α,β-unsaturated- N-carboalkoxy- N, O-acetals or β-methoxymethyl- N-carboalkoxy-enamines. The cycloaddition was conducted using Sc(OTf) 3 as a mild Lewis acid affording the ENDO adducts in moderate yields.
三环螺-N,O-缩醛通过将羟甲基取代的二烯环加成到亚胺离子活化的亲二烯体,由α,β-不饱和-N-碳烷氧基-N,O-缩醛或β的酸解产生-甲氧基甲基-N-碳烷氧基-烯胺。使用Sc(OTf) 3 作为温和的路易斯酸进行环加成,以中等产率提供ENDO加合物。