Regioselective Decarboxylative Direct C–H Arylation of Boron Dipyrromethenes (BODIPYs) at 2,6-Positions: A Facile Access to a Diversity-Oriented BODIPY Library

Abstract

A palladium-catalyzed regioselective decarboxylative direct C-H arylation of boron dipyrromethenes (BODIPYs) at the 2,6-positions has been developed as a late-stage approach to rapidly assemble a diversity-oriented BODIPY library. With the complement of this protocol, the direct C-H arylation of BODIPYs becomes regiocontrollable at α- and β-positions. A new type of indole-fused BODIPY exhibiting bright red/NIR fluorescence with a large molar extinction coefficient (145,500 M(-1) cm(-1)) and a high quantum yield (71%) has been synthesized for the first time.

Tandem Regioselective Substitution and Palladium‐Catalyzed Ring Fusion Reaction for Core‐Expanded Boron Dipyrromethenes with Red‐Shifted Absorption and Intense Fluorescence

“… (a) Linear and aromatic ring fusion modification of BODIPY core. (b) Recently developed diindole‐fused BODIPY by You and co‐workers …”

“…We reasoned that the late‐stage intramolecular arylation on the 2,6‐positions of BODIPY core, by replacing the two bromine atoms with the above‐mentioned two carbon atoms in a palladium‐catalyzed intramolecular C−C coupling ring fusion reaction, would make the system susceptible to the annulations(s) of indole ring(s). During preparation of this manuscript, You, Wu and co‐workers disclosed the preparation of a diindole‐fused BODIPY (one example only) via the palladium‐catalyzed regioselective decarboxylative C−H arylation of the BODIPY core with ortho ‐nitrobenzoic acid and subsequent Cadogan (an intramolecular reductive cyclization) reaction . Herein, we report the efficient synthesis and the optical and electronic properties of a set of diindole‐annulated BODIPYs 1 a – c and the unsymmetrical core‐expanded BODIPYs 5 and 6 based on a regioselective nucleophilic substitution reaction of 2,3,5,6‐tetrabromoBODIPY with aryl amines or phenol and the subsequent palladium‐catalyzed intramolecular C−C coupling ring fusion reactions.…”

Recent chemo‐/biosensor and bioimaging studies based on indole‐decorated BODIPYs

“…Apart from their sensing properties and applications, indole–BODIPY conjugates have been also used and studied in different disciplines for diverse purposes including assessing fluorescence properties, designing novel supramolecular scaffolds and structures, investigating optical characteristics, and engineering novel solar cells . However, here we aim to emphasize the capability and practicability of indole–BODIPY conjugates for sensing chemical and/or biological entities and for bioimaging studies, therefore the above‐mentioned applications in other fields were regarded as being out of the scope of the present article.…”

Strongly Coupled Oxasmaragdyrin–BF2 Chelated Dipyrrin Dyads: Syntheses, X‐ray Structure, Ground‐ and Excited‐State Charge‐Transfer Interactions

“…[71,72] Furthermore, BODIPYs are easily amenable to structural modifications, hence the electronic properties of thesed yes can be fine-tuned at will by introducing appropriate substituents on the BODIPY core. [73][74][75] In this regard, we recently reported the facile synthesis of 3-pyrrolyl BODIPYs (pyrBODIPY)i nw hicht he spectrala nd electrochemical studies showedt hat the presence of pyrrolyl group at the a-position of BODIPY significantly alters the electronic properties. [76] In addition, the appended pyrrole ring on the BODIPY is easy to functionalize and the functionalized 3-pyrrolyl BODIPYsc an be used as synthons to prepares everal interesting fluorescent compounds with variety of applications.…”