Synthetic Organic & Medicinal Chemistry Laboratory, Shanghai Institute of Materia Medica, Shanghai 201203, China.
J Org Chem. 2011 Nov 4;76(21):8833-9. doi: 10.1021/jo2015483. Epub 2011 Oct 7.
The cyclization reactions of arylamines with 2-deoxy-D-ribose or glycals were reinvestigated in the current report. In the montmorillonite KSF- or InCl(3)-initiated reactions of 2-deoxy-D-ribose with arylamines, a pair of diastereomeric tetrahydro-2H-pyran-fused tetrahydroquinolines was obtained in a nearly 1:1 ratio where the structure of one diastereomer was incorrectly assigned in the literature. Meanwhile, the diastereoselectivity in InBr(3)-catalyzed cyclization of glycals with arylamines was also incorrectly reported previously. It was found that high diastereomeric selectivity was achieved only when a C5-substituted glycal was used; otherwise, a pair of diastereomers was obtained in moderate yield with 1:1 diastereomeric ratio. Furthermore, tetrahydrofuran-fused tetrahydroquinolines 5b and 5b' were also prepared successfully by using TBDPS-protected ribose as the glycal precursor and montmorillonite KSF as the activator.
本报告重新研究了芳胺与 2-脱氧-D-核糖或糖醛的环化反应。在蒙脱土 KSF 或 InCl(3)引发的 2-脱氧-D-核糖与芳胺的反应中，几乎以 1:1 的比例得到一对非对映异构体的四氢-2H-吡喃并四氢喹啉，其中一个非对映异构体的结构在文献中被错误指定。同时，先前报道的 InBr(3)催化糖醛与芳胺的环化反应的非对映选择性也是不正确的。研究发现，只有当使用 C5 取代的糖醛时，才能实现高非对映选择性；否则，以中等产率得到一对非对映异构体，非对映异构体比例为 1:1。此外，还成功地使用 TBDPS 保护的核糖作为糖醛前体和蒙脱土 KSF 作为活化剂，制备了四氢呋喃并四氢喹啉 5b 和 5b'。
