A Metal‐Free Oxidative Dehydrogenative Diels–Alder Reaction for Selective Functionalization of Alkylbenzenes

Abstract

Functionalization of C(sp )-H bonds under metal-free reaction conditions is a great challenge due to poor bond reactivity. A novel metal-free oxidative dehydrogenative Diels-Alder reaction of alkylbenzene derivatives with alkenes through C(sp )-H bond functionalization is described. The developed oxidative method provides a straightforward approach to biologically relevant 1,4-phenanthraquinone and isoindole derivatives from readily available starting materials. Furthermore, the synthesis of nitrostyrenes from enylbenzene derivatives by selective C(sp )-H bond functionalization has been demonstrated.

Synthetic applications of hydride abstraction reactions by organic oxidants

“…The authors did not report on competitive cycloaddition of the intermediate dienes with DDQ, possibly because the dienophiles that were employed are also extremely reactive. Similarly, Manna and Antonchick reported 95 that p -cymene ( 172 ) can be oxidized in the presence of benzoquinone and 2 equiv. DDQ to form 173 via the intermediate styrene.…”

Sustainable, Oxidative, and Metal‐Free Annulation

“…Very recently,A ntonchick's group contributed to the field of the dehydrogenative Diels-Alder reactions by introducing the cycloaddition of ethylbenzene with electron-deficient alkenes, namely benzoquinones or maleimides (Scheme20). [47] According to the proposed course of reaction, ac harget ransfer complex was formed by as ingle-electron transfer from p-cymene (83)t oD DQ, which leads to generation of ar adical cationic species. Then, intermediate 83 a is formed after abstraction of ah ydrogen atom from the radical cationic species of pcymenebyt he radical anion of DDQ.…”

Aerobic, Metal-Free, and Catalytic Dehydrogenative Coupling of Heterocycles: En Route to Hedgehog Signaling Pathway Inhibitors

“…Early studies by Radner and, later, by Tanaka enlightened Scholl-type reactions through nitrosonium ion-catalyzed coupling . Because of the growing importance of sustainable chemistry, and the ongoing interest of our group in the development of novel metal-free reaction methodologies, nitrosonium salts have attracted our attention . Molecular oxygen is considered the ideal oxidant due to its natural occurrence, inexpensive character, and safe handling .…”