Indian Institute of Technology Indore, Discipline of Chemistry, Simrol, Indore 453552, India.
Org Biomol Chem. 2020 Feb 21;18(7):1337-1342. doi: 10.1039/c9ob02708d. Epub 2020 Jan 30.
A simple and powerful one-pot regioselective 1,6-addition elimination-6π-aza-electrocyclization-aromatization reaction of vinyl/dienyl-substituted para-quinone methides with a bunch of cyclic sulfamidate imines as 2C1N synthons promoted by DABCO as a solid organobase in an open atmosphere is reported for the first time. The above-mentioned C-C and C-N bond formation process provides good to high yields of a wide range of symmetrically and unsymmetrically 2,4,6-trisubstituted pyridines possessing a sterically hindered phenolic moiety at the C4-position with a broad substrate scope. This domino [3 + 3] cyclization reaction gives rise to several compatible functionalities under metal-free conditions. Finally, the large-scale synthesis of pyridine derivatives has been demonstrated.
本文首次报道了在 DABCO 作为固态有机碱的促进下，乙烯基/二烯基取代对醌甲亚胺与一系列环状磺酰胺亚胺的一锅法区域选择性 1,6-加成消除-6π-aza-电环化-芳构化反应。上述 C-C 和 C-N 键形成过程以良好至高产率得到了广泛的对称和不对称的 2,4,6-三取代吡啶，其在 C4 位具有空间位阻的酚基部分，底物范围广泛。该串联[3 + 3]环化反应在无金属条件下产生了几种相容的官能团。最后，进行了吡啶衍生物的大规模合成。
