presence of the N-heterocyclic carbene gold catalyst (NHC-AuIPr, 7), propargyl esters 1a–f and 13 undergo a [4C+3C] cycloaddition reaction with cyclopentadiene and furan under mild conditions. The evidence suggests that the formation of the seven-membered ring occurs by a direct cycloaddition process, rather than a stepwise cyclopropanation/Cope rearrangement sequence.
在 N-杂环卡宾
金催化剂 (NHC-AuIPr, 7 ) 的存在下,炔
丙酯1a – f和13在温和条件下与
环戊二烯和
呋喃发生 [4C+3C] 环加成反应。证据表明,七元环的形成是通过直接环加成过程而不是逐步
环丙烷化/Cope 重排序列发生的。