Photooxygenations and Self-Sensitizations of Naphthylamines: Efficient Access to Iminoquinones

Abstract

A series of spiro [fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (SFDBAO) derivatives have been concisely and cleanly obtained by exposure to sunlight without external photosensitizers in the higher yields than that when using a UV lamp. An interesting autocatalyst and self-sensitive procedure have been proposed to explain the effective photooxygenation. SFDBAO derivatives exhibit the continuous π-stacks in single-crystal and electron-withdraw properties with red light-emitting and photovoltaic properties.

Tuning the Absorption, Fluorescence, Intramolecular Charge Transfer, and Intersystem Crossing in Spiro[fluorene]acridinone

“…Spiro[fluorene‐9,7’‐dibenzo[c,h]acridine] (SFDBA) precursor was prepared via a one‐pot cyclization reaction in the presence of an excessive amount of acid catalyst [77,78] . SFDBAO and Br‐SFDBAO building blocks were synthesized via an eco‐friendly sunlight photooxygenation of Br‐SFDBA by an auto‐catalytic and self‐sensitive procedure [75,79] . C‐2 and C‐9’ pyrene‐functionalized SFDBAO were obtained by a Suzuki coupling reaction between pyrene boronic ester and Br‐SFDBAO at either C‐2 or C‐9’ position.…”

“…The synthesis of the SFDBAO derivatives is known from our previous research (Scheme S1). [74][75][76] Spiro[fluorene-9,7'dibenzo[c,h]acridine] (SFDBA) precursor was prepared via a one-pot cyclization reaction in the presence of an excessive amount of acid catalyst. [77,78] SFDBAO and Br-SFDBAO building blocks were synthesized via an eco-friendly sunlight photooxygenation of Br-SFDBA by an auto-catalytic and self-sensitive procedure.…”

“…[77,78] SFDBAO and Br-SFDBAO building blocks were synthesized via an eco-friendly sunlight photooxygenation of Br-SFDBA by an auto-catalytic and self-sensitive procedure. [75,79] C-2 and C-9' pyrene-functionalized SFDBAO were obtained by a Suzuki coupling reaction between pyrene boronic ester and Br-SFDBAO at either C-2 or C-9' position.…”

“…It facilitates the rational design of heavy atom‐free triplet photosensitizers (HAF‐PSs) and fluorescent probes. Here, we used spiro[fluorene‐9,7’‐dibenzo[c,h]acridine]‐5’‐one (SFDBAO) as a versatile platform [74–76] . On one hand, the SFDBAO backbone is easily synthesized by an eco‐friendly and low‐cost oxygen‐mediated photooxidation upon sunlight irradiation.…”

“…Here, we used spiro[fluorene-9,7'-dibenzo[c,h]acridine]-5'-one (SFDBAO) as a versatile platform. [74][75][76] On one hand, the SFDBAO backbone is easily synthesized by an eco-friendly and low-cost oxygen-mediated photooxidation upon sunlight irradiation. On the other hand, SFDBAO, a spirocyclic aromatic hydrocarbon, not only has a typical spiro-arranged skeleton but also incorporates a carbonyl group, which either acts as an electron acceptor or induces ISC based on the EI-Sayed rule (Scheme 1).…”