A synthesis of spiroindolo[2, 1-b]quinazoline-6, 2'-pyrido[2, 1-b][1, 3]oxazines from tryptanthrins and Huisgen zwitterions. Issue 10 (19th May 2021) - Yavari, Issa
Abstract: The Huisgen zwitterionic intermediates, generated in situ from N -heterocycles and acetylenic esters were intercepted by tryptanthrins to afford novel spiroindolo[2, 1- b ]quinazoline-6, 2'-pyrido[2, 1- b ][1, 3]oxazines in CH2 Cl2 at room temperature. Clear evidence for the structure of a derivative was obtained from single-crystal X-ray analyses. The most important feature of this reaction is the fact it forms two stereogenic centers, one of which is quaternary with remarkable diastereoselectivity. Graphical Abstract: