Wang J.
Mao C.
Feng P.
*
Zheng N.
* University of Arkansas, Fayetteville and University of California Riverside, USA
Visible-Light-Mediated [4+2] Annulation of
N-Cyclobutylanilines with Alkynes Catalyzed by Self-Doped Ti
3+@TiO
2
.
Chem. Eur. J. 2017;
23: 15396-15403
Key words
heterogeneous catalysis - titanium catalysis - photocatalysis - annulation - cyclobutylanilines - alkynes
Significance
A self-doped Ti3+@TiO2 catalyst was prepared as shown in equation 1. The [4+2] annulation of N-cyclobutylanilines with alkynes took place in the presence of Ti3+@TiO2 under visible-light irradiation in air to give the corresponding annulation products 1a–d in up to 85% yield (eq. 2; 15 examples).
Comment
The catalyst was recovered by centrifugation, washed with t-BuOH, and reused four times for the formation of 1a (fifth run: 79% yield). When the reaction of 4-t-butyl-N-cyclobutylaniline and prop-1-yn-1-ylbenzene was carried out in the presence of Ti3+@TiO2 (10 mol%) or rose bengal (5 mol%) for 13 h, product 2 was obtained in yields of 43% and 19%, respectively (eq. 3).
