Potassium Triisopropoxyborohydride

Banfi, Luca; Narisano, Enrica; Riva, Renata

doi:10.1002/047084289x.rp255

Cited by 6 publications

(7 citation statements)

References 30 publications

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“…We devised an efficient, high-yielding approach to synthesize derivatives of hydroxymethyl JF 526 (HM-JF 526 ), leveraging our divergent synthesis of JF 526 and the differential reactivity of carboxyl groups and lactones with borohydride reductants. 55 Treatment of dibromofluoran 22 with LiBH 4 at ambient temperature selectively reduced the lactone to a cyclic ether leaving the 6-carboxy group intact, providing 33 in moderate yield (54%; Figure 7b). Formation of 6- t -butyl ester with acetal 23 gave 34 , allowing Pd-catalyzed cross-coupling with 29 .…”

Section: Resultsmentioning

confidence: 99%

“…Given the similarity of the K L–Z values for JF 526 and SiR, we were curious if a hydroxymethyl derivative of JF 526 would show comparable utility to 32 in SMLM. We devised an efficient, high-yielding approach to synthesize derivatives of hydroxymethyl JF 526 (HM-JF 526 ), leveraging our divergent synthesis of JF 526 and the differential reactivity of carboxyl groups and lactones with borohydride reductants . Treatment of dibromofluoran 22 with LiBH 4 at ambient temperature selectively reduced the lactone to a cyclic ether leaving the 6-carboxy group intact, providing 33 in moderate yield (54%; Figure b).…”

Section: Resultsmentioning

confidence: 99%

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Rational Design of Fluorogenic and Spontaneously Blinking Labels for Super-Resolution Imaging

et al. 2019

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Rhodamine dyes exist in equilibrium between a fluorescent zwitterion and a nonfluorescent lactone. Tuning this equilibrium toward the nonfluorescent lactone form can improve cell-permeability and allow creation of “fluorogenic” compounds—ligands that shift to the fluorescent zwitterion upon binding a biomolecular target. An archetype fluorogenic dye is the far-red tetramethyl-Si-rhodamine (SiR), which has been used to create exceptionally useful labels for advanced microscopy. Here, we develop a quantitative framework for the development of new fluorogenic dyes, determining that the lactone–zwitterion equilibrium constant (KL–Z) is sufficient to predict fluorogenicity. This rubric emerged from our analysis of known fluorophores and yielded new fluorescent and fluorogenic labels with improved performance in cellular imaging experiments. We then designed a novel fluorophore—Janelia Fluor 526 (JF526)—with SiR-like properties but shorter fluorescence excitation and emission wavelengths. JF526 is a versatile scaffold for fluorogenic probes including ligands for self-labeling tags, stains for endogenous structures, and spontaneously blinking labels for super-resolution immunofluorescence. JF526 constitutes a new label for advanced microscopy experiments, and our quantitative framework will enable the rational design of other fluorogenic probes for bioimaging.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Rational Design of Fluorogenic and Spontaneously Blinking Labels for Super-Resolution Imaging

et al. 2019

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“…Many reducing agents have been used to reduce aromatic nitro compounds with the most classic being zinc, tin, or iron in the presence of an acid . Other reagents used include hydrazine, Ru 3 (CO) 12 , TiCl 4 −dialkyl telluride, (C 2 H 5 O) 2 PCl, metal hydride complexes (e.g., NaBH 4 −NiCl 2 ), and sulfides (e.g., sodium sulfhydrate, ammonium sulfide, or polysulfides). Aromatic nitro compounds can also be reduced electrochemically or enzymatically .…”

Section: Introductionmentioning

confidence: 99%

Samarium(0) and 1,1‘-Dioctyl-4,4‘-Bipyridinium Dibromide: A Novel Electron-Transfer System for the Chemoselective Reduction of Aromatic Nitro Groups

Liu

2001

J. Org. Chem.

119

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A mild and efficient electron-transfer method was developed for the chemoselective reduction of aromatic nitro groups using samarium(0) metal in the presence of a catalytic amount of 1,1'-dioctyl-4,4'-bipyridinium dibromide. This method was found to give the product aromatic amine in 79-99% yield with selectivity over a number of other functional and protecting groups such as alkene, azide, benzyl ether, nitrile, amide, halide, p-toluenesulfonamide, t-Boc, tert-butyldiphenylsilyl ether, and aliphatic nitro groups. Our results also indicate that samarium(0) plays an important role in the reduction process and that 1,1'-dioctyl-4,4'-bipyridinium dibromide acts as an electron-transfer catalyst and is essential in the activation of samarium(0) metal. The major active reducing agent responsible for the reduction is believed to be the radical cation species formed from 1,1'-dioctyl-4,4'-bipyridinium dibromide.

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“…The use of InCl 3 catalyst is essential because no reduction took place in the absence of InCl 3 . As Et 3 SiH has no radical reactivity, indium hydride is a plausibly reactive species. In our Bu 3 SnH−InCl 3 and NaBH 4 −InCl 3 systems, various alkyl halides were reduced with a catalytic amount of InCl 3 without any initiators. , Although the exact reason Et 3 B and equimolar InCl 3 are necessary in the Et 3 SiH−InCl 3 system is not clear yet, this may be due to the low concentration of indium hydride because the transmetalation of Et 3 SiH−InCl 3 is slow, especially in CH 2 Cl 2 .…”

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confidence: 99%