A synthesis of spiroindolo[2,1-b]quinazoline-6,2'-pyrido[2,1-b][1,3]oxazines from tryptanthrins and Huisgen zwitterions

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 CH2Cl2 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.

Automated summary

The study utilized Huisgen zwitterionic intermediates and tryptanthrins to generate novel compounds at room temperature, with two stereogenic centers formed, one of which is quaternary and shows remarkable diastereoselectivity.