Silver/Scandium-Cocatalyzed Bicyclization of β-Alkynyl Ketones Leading to Benzo[<i>c</i>]xanthenes and Naphtho[1,2-<i>b</i>]benzofurans
作者:Ke Chen、Shuai Liu、Dan Wang、Wen-Juan Hao、Peng Zhou、Shu-Jiang Tu、Bo Jiang
DOI:10.1021/acs.joc.7b02134
日期:2017.11.3
The combination of AgTFA and Sc(OTf)3 enables the bimetallic synergistic catalysis of β-alkynyl ketones and para-quinone methides (p-QMs), allowing direct synthesis of 17 examples of benzo[c]xanthenes with generally good yields through a benzannulation/1,6-addition/cyclization sequence. Exchanging p-QMs for quinone imine ketal resulted in 10 examples of tetracyclic naphtho[1,2-b]benzofurans via a similar
AgTFA和Sc(OTf)3的组合可实现β-炔基酮和对醌甲基化物(p -QMs)的双金属协同催化作用,从而可以直接合成17种实例的苯并[ c ]黄嘌呤,并通过苯甲环化获得良好的收率。 / 1,6-加成/环化序列。通过类似的苯环/ 1,4-加成/环化级联反应将p- QM交换为醌亚胺缩酮可得到10个四环萘并[1,2- b ]苯并呋喃实例。在这些反应过程中,AgTFA和Sc(OTf)3与C(sp 3的实现)可以完全兼容。β-炔基酮单元上与羰基相邻的)-H官能化。