A metal- and catalyst-free photoinduced radical
cascade hydroalkylation of 1,7-enynes has been
disclosed. The process is triggered by a SET event involving a photoexcited
electron-donor-aceptor complex between NHPI ester and Hantzsch ester, which
decomposes to afford a tertiary radical that is readily trapped by the enyne. <a>The method provides an operationally simple, robust and
step-economical approach to the construction of diversely functionalized
dihydroquinolinones bearing quaternary-centers. A sequential one-pot hydroalkylation-isomerization
approach is also allowed giving access
to a family of quinolinones. A wide substrate scope and high functional group tolerance was observed in both approaches</a>.
Yb(OTf)3-Catalyzed Reactions of 5-Alkylidene Meldrum′s Acids with Phenols: One-Pot Assembly of 3,4-Dihydrocoumarins, 4-Chromanones, Coumarins, and Chromones.