Nitrile Oxide versus Nitrone – Switching Regioselectivity of Intramolecular 1,3‐Dipolar Cycloadditions towards the Preparation of Aminopiperidinecarboxylates

Würdemann, Martina; Christoffers, Jens

doi:10.1002/ejoc.201301039

Cited by 11 publications

(3 citation statements)

References 54 publications

(11 reference statements)

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“…O ‐(7‐Azabenzotriazol‐1‐yl)‐ N , N , N′,N′ ‐tetramethyluronium hexafluorophosphate (HATU) in the presence of ethyldiisopropylamine (DIPEA) was chosen as the coupling reagent for this and all further amidations . Two dyes with thiol‐functionalization for surface binding were then prepared: the first one by amidation of acid 4 with cysteamine (27 % of product 7 ), and for the second compound, an ethylene spacer was introduced by coupling with N ‐Boc ethylenediamine ( 8 ) (81 % of product 9 ) followed by N‐deprotection with HCl (formed in situ by solvolysis of AcCl in MeOH) (93 % of product 8 ) and another amidation with β‐mercaptopropionic acid (26 % of product 11 ). For binding to streptavidin, the dye with one primary amino function 10 was converted with biotin ( N ‐hydroxy)succinimide active ester (biotinOsucc) in the presence of DIPEA to give the compound 12 in quantitative yield.…”

Section: Resultsmentioning

confidence: 99%

Bifunctional Diaminoterephthalate Fluorescent Dye as Probe for Cross‐Linking Proteins

Wallisch

Sulmann

Koch

et al. 2017

Chemistry A European J

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Diaminoterephthalates are fluorescent dyes and define scaffolds, which can be orthogonally functionalized at their two carboxylate residues with functional residues bearing task specific reactive groups. The synthesis of monofunctionalized dyes with thiol groups for surface binding, an azide for click chemistry, and a biotinoylated congener for streptavidin binding is reported. Two bifunctionalized dyes were prepared: One with an azide for click chemistry and a biotin for streptavidin binding, the other with a maleimide for reaction with thiol and a cyclooctyne moiety for ligation with copper-free click chemistry. In general, the compounds are red to orange, fluorescent materials with an absorption at about 450 nm and an emission at 560 nm with quantum yields between 2-41 %. Of particular interest is the maleimide-functionalized compound, which shows low fluorescence quantum yield (2 %) by itself. After addition of a thiol, the fluorescence is "turned on"; quantum yield 41 %.

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Section: Resultsmentioning

confidence: 99%

Bifunctional Diaminoterephthalate Fluorescent Dye as Probe for Cross‐Linking Proteins

Wallisch

Sulmann

Koch

et al. 2017

Chemistry A European J

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“…It was introduced by coupling carboxylic acid 1 with N -Boc-ethylene diamine (prepared as reported in the literature) following the above proven HATU protocol. Deprotection of the carbamate function was accomplished with HCl generated in situ from AcCl in MeOH, furnishing primary amine 6 with 75% yield in two steps from compound 1 . Coupling with cyclooctyne building block 7 proceeded straightforwardly with an almost quantitative yield of probe 8 .…”

Section: Resultsmentioning

confidence: 99%

Mapping Calcium-Sensitive Regions in the Neuronal Calcium Sensor GCAP2 by Site-Specific Fluorescence Labeling

et al. 2016

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Myristoylation of most neuronal calcium sensor proteins, a group of EF-hand calcium-binding proteins mainly expressed in neuronal tissue, can have a strong impact on protein dynamics and functional properties. Intracellular oscillations of the free Ca(2+) concentration can trigger conformational changes in Ca(2+) sensors. The position and possible movements of the myristoyl group in the photoreceptor cell-specific Ca(2+) sensor GCAP2 are not well-defined but appear to be different from those of the highly homologous cognate GCAP1. We designed and applied a new group of diaminoterephthalate-derived fluorescent probes to label GCAP2 at a covalently attached 12-azido-dodecanoic acid (a myristoyl substitute) and at cysteine residues in critical positions. Fluorescence emission of dye-labeled GCAP2 decreased when going from low (10(-9) M) to high [Ca(2+)] (10(-3) M), reaching a half-maximal effect of fluorescence emission at 0.44 ± 0.07 μM. The modified acyl group can therefore monitor changes in the protein conformation during binding and dissociation of Ca(2+) in the physiological range of free [Ca(2+)]. However, fluorescence quenching studies showed that the dye-acyl chain was shielded from the quencher by an adjacent polypeptide region. Further probing three cysteine positions (C35, C111, and C131) by dye labeling revealed that all positions were also sensitive to a change in [Ca(2+)], but only one (C131) was sensitive to a change in [Mg(2+)]. We suggest a scenario during illumination of the photoreceptor cell in which Ca(2+) dissociates first from low and medium affinity binding sites. These steps are sensed by dyes in cysteines at positions 35 and 111. Release of Ca(2+) from high affinity sites is sensed by regions adjacent to the dye-labeled fatty acid and involves the critical conformational change leading to activating guanylate cyclase.

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“…From the aldehyde 9 the corresponding oxime was formed under buffered conditions [ 30 ] and the crude material was directly submitted to reduction with LiAlH 4 [ 31 ] to furnish amine 10 as a practically pure compound (72%) ( Scheme 3 ). The conversion of amine 10 with chlorouracil 3 proceeded with NEt 3 as base in EtOH at elevated temperature.…”

Section: Resultsmentioning

confidence: 99%

A robust synthesis of 7,8-didemethyl-8-hydroxy-5-deazariboflavin

Bender¹,

Mouritsen²,

Christoffers³

2016

Beilstein J. Org. Chem.

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SummaryThe biosynthetic precursor of redox cofactor F420, 7,8-didemethyl-8-hydroxy-5-deazariboflavin, was prepared in four steps from 6-chlorouracil, 2-chloro-4-hydroxybenzaldehyde and bis-isopropylidene protected D-ribose. The latter aldehyde was transformed to the corresponding protected ribitylamine via the oxime, which was submitted to reduction with LiAlH4. Key advantage compared to previous syntheses is the utilization of a polyol-protective group which allowed the chromatographic purification of a key-intermediate product providing the target compound with high purity.

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Nitrile Oxide versus Nitrone – Switching Regioselectivity of Intramolecular 1,3‐Dipolar Cycloadditions towards the Preparation of Aminopiperidinecarboxylates

Cited by 11 publications

References 54 publications

Bifunctional Diaminoterephthalate Fluorescent Dye as Probe for Cross‐Linking Proteins

Bifunctional Diaminoterephthalate Fluorescent Dye as Probe for Cross‐Linking Proteins

Mapping Calcium-Sensitive Regions in the Neuronal Calcium Sensor GCAP2 by Site-Specific Fluorescence Labeling

A robust synthesis of 7,8-didemethyl-8-hydroxy-5-deazariboflavin

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