Exploring the Application of the Negishi Reaction of HaloBODIPYs: Generality, Regioselectivity, and Synthetic Utility in the Development of BODIPY Laser Dyes

Abstract

The generality of the palladium-catalyzed C−C coupling Negishi reaction when applied to haloBODIPYs is demonstrated on the basis of selected starting BODIPYs, including polyhalogenated and/or asymmetrical systems, and organozinc reagents. This reaction is an interesting synthetic tool in BODIPY chemistry, mainly because it allows a valuable regioselective postfunctionalization of BODIPY chromophores with different functional groups. In this way, functional patterns that are difficult to obtain by other procedures (e.g., asymmetrically functionalized BODIPYs involving halogenated positions) can now be made. The regioselectivity is achieved by controlling the reaction conditions and is based on almost-general reactivity preferences, and the nature of the involved halogens and their positions. This ability is exemplified by the preparation of a series of new BODIPY dyes with unprecedented substitution patterns allowing noticeable lasing properties.

Synthesis and Characterization of Boron Difluoride Complexes Bearing π-Expanded Pyridine Ligands as Organic Fluorochromes

“…Particularly, boron dipyrromethene (BODIPY) is one of the most popular and useful organic dyes because of its high molar extinction coefficient and fluorescence quantum yield. Furthermore, BODIPY is easy to modify to afford various derivatives; this not only enables a control of its optical properties but also lends utility to a variety of applications such as for molecular probes, labeling reagents, imaging, drug delivery, fluorescent switches, organic light-emitting devices, tunable laser dyes, light-harvesting systems, and sensitizers for solar cells . However, BODIPYs have several serious defects to be solved.…”

One‐Pot Preparation of Non‐Symmetric meso‐Aryl‐BODIPYs: Functional Derivatives with Unusual Reactivity

“…The halogenation of BODIPYs is one of the most important transformations as it leads to compounds that are sufficiently stable to be isolated, but amenable towards a range of nucleophilic displacement and metal‐catalysed coupling reactions . Chlorination was studied with dimesityl derivative 1 .…”

Synthesis of BODIPY dyes through postfunctionalization of the boron dipyrromethene core

“…Our research groups also described the Negishi reaction of haloBODIPYs. 303 The following preferences (with respect to halogen and BODIPY position) for the Negishi reaction in haloBODIPYs were observed: I > Br > Cl and 8 > 3/5 ~ 1,7 > 2/6. The halogen preference agrees with that found for related Pdcatalyzed cross-couplings in haloBODIPYs, whereas the position preference matches that reported for Suzuki and Sonogashira reactions in chlorinated and brominated BODIPYs.…”

“…208,298,299,300,301,302 . 298,299,303,304 The yields of the Suzuki reaction of 8-haloBODIPYs 414 (with X = Cl, Br, I) with phenylboronic acid to afford 415f increased in the following order: Cl (36%) < Br (53%) < I (75%). Our research groups also described the Negishi reaction of haloBODIPYs.…”

“…The halogen preference agrees with that found for related Pdcatalyzed cross-couplings in haloBODIPYs, whereas the position preference matches that reported for Suzuki and Sonogashira reactions in chlorinated and brominated BODIPYs. Although the Negishi reaction has been scarcely used in the development of dipyrrinato BF2 complexes, 159,303 it is a versatile and selective synthetic tool in BODIPY chemistry, mainly because it allows for a valuable regioselective postfunctionalization of BODIPY with different functional groups. In this way, functional patterns that are difficult to obtain by other procedures (e.g., unsymmetrically functionalized BODIPYs involving polyhalogenated positions) can now be made.…”