A Sc(OTf)₃-catalyzed tandem (3 + 3)-annulation/lactonization of donor-acceptor cyclopropane 1,1-dieters with salicylaldehyde nitrones has been reported, affording a wide range of tetrahydrochromeno[4,3-c][1,2]oxazin-5(1H)-ones in moderate yields with excellent diastereoselectivities. Besides, the gram-scale reaction has also been explored to demonstrate the utility of this protocol. Moreover, the mechanism was investigated through control experiments, which show the reaction proceeds via a tandem (3 + 3)-annulation/lactonization reaction.

中文翻译：

---

Sc(OTf)3-催化环丙烷与水杨醛硝酮的串联 (3+3)-环化/内酯化反应生成多环 1,2-恶嗪

据报道，Sc(OTf) ₃催化供体-受体环丙烷 1,1-二酯与水杨醛硝酮的串联 (3 + 3) 成环/内酯化反应，可产生多种四氢色烯[4,3- c ][1 ,2]恶嗪-5(1 H )-酮，产率适中，具有优异的非对映选择性。此外，还探索了克级反应来证明该方案的实用性。此外，通过对照实验研究了该机理，结果表明该反应是通过串联 (3 + 3)-环化/内酯化反应进行的。