Diels-Alder reactions of 2-pyrones. Direction of the addition reaction with acetylenes

A Mild Benzannulation through Directed Cycloaddition Reactions

“…2‐Pyrones represented a more challenging class of substrates as their cycloadditions with alkynes generally require very high reaction temperatures (typically >140 °C) and long reaction times 7. Moreover, such processes are often poorly regioselective and are relatively low yielding 8. We report herein the successful implementation of this concept for the mild and regiospecific formation of 1,2,3‐trisubstituted benzenes 9.…”

Synthesis of the staurosporine aglycone

“…Our initial approach to the pyranoindoione (81) was to disconnect back to pyranoindolone (83), which in turn could be obtained from previously synthesised pyranoindolone (73).…”

Scalable Multicomponent Synthesis of (Hetero)aryl‐Substituted Phenyls: Focus on Metal‐Free Halogenated Biaryls, 3‐Arylindoles, and Isourolithine A Synthesis

“…Therefore, we planned a novel synthetic strategy, identifying an alternative metal‐free activation method for the Diels‐Alder reaction in order to avoid the use of a high‐pressure apparatus. Considering that metal‐free thermal activation of electron‐poor alkynes in Diels‐Alder reactions for biaryls synthesis has already been demonstrated to be an achievable target,a cheap metal vessel seemed to be a convenient option to export the advantages of a hyperbaric multicomponent protocol to industrial plants and less equipped laboratories. In contrast with other systems requiring glass vessels, like microwave and Q‐tube, metal vessels can bear higher pressures and they are usually equipped with a safety gauge.…”