Direct β‐Selective Styrylation of BODIPY Dyes via Palladium(II)‐Catalyzed C−H Functionalization

Abstract

A general and efficient method for direct b-selective styrylation of BODIPYs has been developed based on Palladium(II)-catalyzed oxidative CÀH functionalization. The high b-regioselectivity was confirmed by X-ray analysis. The resulting dyes showed bathochromically shifted absorption and emission compared to that of the starting BODIPYs. This strategy, as a late-stage approach to rapidly assemble a diversity-oriented BODIPY library, provides a straightforward way to extend the conjugation of the BODIPY system at 2,6positions. arylation at 2,6-positions of BODIPY reported by You and Wu (Scheme 1a). [11c] Since Fujiwara's discovery of the direct olefination of benzene, [12] the regioselective palladium(II)-catalyzed direct alkenylation has been successfully applied in several (hetero)arenes. [13] Due to the higher reactivity of the 2,6-positions observed toward electrophilic substitution, [8d] we wondered that the direct oxidative styrylation of BODIPY may occur regioselectively at these positions. Herein, by taking advantage of the high electron density at 2,6-positions of BODIPY, we report a highly regioselective, direct bstyrylation of BODIPY chromophores with a variety of styrenes (Scheme 1c). The regioselectivity was confirmed by X-ray analysis. The amounts of monoand distyrylated products could be tuned by varying the ratio of the catalyst and oxidant. These resultant b-styryl substituted BODIPYs 1-3 show red-shift in both absorption and emission maximum in far-red to NIR region with large Stokes shifts.

Pd‐Catalyzed Sonogashira Cross‐Coupling Reactions of gem‐Dibromovinyl BODIPY Derivatives

“…Tris-(dibenzylideneacetone) dipalladium as catalyst, along with ligand TFP was used for the coupling of 1 with trimethylphenyl tin, which gave two products, compound 27 featuring two phenyl groups attached directly to the vinyl moiety and a monobromo monophenyl alkene derivative 28 (Scheme 6). Recently the synthesis of compound 27 has also been reported [21] using Pd catalyzed regioselective styrylation of BODIPY dyes via direct CH activation. Full Papers doi.org/10.1002/ejoc.202100133…”

Pd-Catalyzed Intermolecular Dehydrogenative Heck Reactions of Five-Membered Heteroarenes

“…Pd II -catalyzed DHRs of boron dipyrromethene derivatives were carried out with either styrenes and AgOAc [75] or acrylates and AgOCOCF3 (Equation 38 Pd II -catalyzed DHRs of boron dipyrromethene derivatives were carried out with either styrenes and AgOAc [75] or acrylates and AgOCOCF 3 (Equation (38)) [76], affording dyes with improved properties. Pd II -catalyzed DHRs of boron dipyrromethene derivatives were carried out with either styrenes and AgOAc [75] or acrylates and AgOCOCF3 (Equation (38)) [76], affording dyes with improved properties. (38)…”

β-Boronic Acid-Substituted Bodipy Dyes for Fluorescence Anisotropy Analysis of Carbohydrate Binding

“…27,38,39 This position is more difficult to become selectively modified during the synthesis because of the least-positive charge. 27,40,41 To the best of our knowledge, only one Bodipy with β-boronic acid has been described in the literature for sugar labeling. 42 However, the reported binding affinity for fructose is low compared to that of other fluorescent labels (K b (fructose) ≈ 45 M −1 at pH 9.5).…”

“…In this respect, Bodipys are frequently used as labels because of their good synthetic accessibility and their fluorescence properties. − However, so far, there are only a few examples of Bodipy-based probes for carbohydrates: the most straightforward are Bodipy dyes with the boronic acid at the meso position, ,− but the BF 2 -unit from the Bodipy core was also replaced by boronic acid . Especially, the β-position (in Figure a, the positions C3 and C10, and in Figure b, the positions C11 and C18, respectively) of the Bodipy core is very attractive for fluorescence anisotropy measurements as the transition dipole moment is oriented along the axis which connects the β-positions. ,, This position is more difficult to become selectively modified during the synthesis because of the least-positive charge. ,, To the best of our knowledge, only one Bodipy with β-boronic acid has been described in the literature for sugar labeling . However, the reported binding affinity for fructose is low compared to that of other fluorescent labels ( K b (fructose) ≈ 45 M –1 at pH 9.5).…”