Practical access to fluorescent 2,3-naphthalimide derivatives via didehydro-Diels–Alder reaction

Abstract

A practical and efficient approach for the synthesis of fluorescent 2,3-naphthalimide derivatives has been developed from readily available starting materials via an intramolecular didehydro-Diels-Alder reaction, which proceeded well under room...

Ambient Synthesis of Tricyclic Naphthalenes via Stepwise Styryl-yne Dearomative Diels–Alder Cyclization

“…Moreover, the key annulation of the sequence is likely a stepwise Diels–Alder reaction, whose energetic profile is surprisingly easier than that of an uncatalyzed concerted process. A similar mechanism is original within the context of dearomative Diels–Alder reactions, which are invariably proposed to be concerted cycloadditions. − According to DFT, stepwise catalytic cyclizations of styryl-ynes are however quite general, and we thus anticipate vast applications of this concept in the future.…”

“…Very similar results were observed by modeling the reaction with 5 MnOOH as a model Mn­(III) derivative ( d ) . The arene-yne cyclization presented here seemed to be a rare event in which the most favorable Diels–Alder mechanism was the stepwise one. − ,, We wondered whether this process might have been a general feature of catalytic dearomative Diels–Alder cyclizations.…”

“…The use of Fe­(II)/Fe­(III) catalysts could allow us to perform the cyclization at 150 °C under microwave conditions . Very recently, Zhang reported an unexpected outcome from the preparation of imido-tethered 1,6-enynes . A cinnamoyl chloride and a propiolamide, in the presence of sodium hydride, afforded the rearomatized styryl-yne Diels–Alder cycloadduct operating at room temperature under air.…”

“…This Diels–Alder cyclization should involve a single transition state (TS) according to the literature. − This pathway should have a lower energetic cost compared to that of a stepwise, two-TS manifold (Scheme ). The latter is a feature of a few processes only, which use strongly polarized reagents and involve a zwitterionic or biradical intermediate.…”

“…5 Very recently, Zhang reported an unexpected outcome from the preparation of imido-tethered 1,6-enynes. 6 A cinnamoyl chloride and a propiolamide, in the presence of sodium hydride, afforded the rearomatized styryl-yne Diels− Alder cycloadduct operating at room temperature under air. A rationale for the ease of this putative dearomative cyclization is, however, still unclear.…”