Novel Use of N-Carboalkoxy α,β-Unsaturated Iminium Ions as Dienophiles in Diels-Alder Reactions
Novel Use of N-Carboalkoxy α,β-Unsaturated Iminium Ions as Dienophiles in Diels-Alder Reactions
复制标题
N-烷氧碳基 α,β-不饱和亚胺离子作为 Dienophiles 在 Diels-Alder 反应中的新用途
作者：
Patrick D. O’Connor;Karsten Körber;M. Brimble
三环螺环-N，O-缩醛是由α，β-不饱和-N-碳烷氧基-N，O-缩醛或β-甲氧甲基-N-碳烷氧基烯胺酸解生成的亚胺离子活化的双烯烃与羟甲基取代的二烯环加成得到的。用Sc(OTf)3作为温和的Lewis酸进行环加成反应，以适中的产率提供内加成物。
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.