Ground-state dioxygen undergoes metal-free [3 + 2]-annulations with allenes and nitrosoarenes under ambient conditions
作者:Jinxian Liu、Manisha Skaria、Pankaj Sharma、Yun-Wei Chiang、Rai-Shung Liu
DOI:10.1039/c7sc01770g
日期:——
heavily on singlet-state 1O2, whereas ground state 3O2 is chemically inactive. Here we report novel [3 + 2]-annulations among ground-state 3O2 (1 bar), allenes, and nitrosoarenes at low temperatures, efficiently yielding dioxygen-containing oxacycles. With less hindered 1-arylallene derivatives, these dioxygen species undergo skeletal rearrangement to 3-hydroxy-1-ketonyl-2-imine oxides. These cycloadditions
具有中性π键基序的分子双氧的环加成反应严重依赖于单重态1 O 2,而基态3 O 2是化学惰性的。在这里,我们报告在低温下基态3 O 2(1 bar),烯和亚硝基芳烃之间的新颖[3 + 2]环,可有效产生含双氧的oxacycles。由于受阻较少的1-芳基丙二烯衍生物,这些双氧物种会发生骨架重排,生成3-羟基-1-酮基-2-亚胺氧化物。这些环加成代表有价值的一锅O,N,O烯的三官能化。我们的EPR实验证实了来自异戊烯/亚硝基芳烃混合物的1,4-双自由基中间体的存在,这表明亚硝基芳烃具有隐藏的双自由基性质。