3,6-Di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) mediated metal-free mild oxidation of thiols to disulfides in aqueous medium

Samanta, Suvendu; Ray, Shounak; Ghosh, Abhisek Brata; Biswas, Papu

doi:10.1039/c6ra01509c

Cited by 40 publications

(19 citation statements)

References 63 publications

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“…Direct oxidative coupling of S−H/S−H to synthesize disulfides has emerged as an important method in organic synthesis due to its step‐ and atom‐economy, and environmental friendliness only with H 2 as a byproduct . The oxidative coupling of thiols are usually accomplished by stoichiometric oxidation or catalytic oxidation with various inorganic reagents (such as KMnO 4 , K 2 S 2 O 8 , halogens) and organic reagents (such as PhI(OAc) 2 , DDQ) . However, most of these reagents are toxic, hazardous and generate a large quantity of wastes.…”

Section: Introductionmentioning

confidence: 99%

Electrochemically Oxidative Coupling of S‐H/S‐H for S‐S Bond Formation: A Facile Approach to Diacid‐disulfides

et al. 2020

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A green electrochemical method of preparing diacid-disulfides has been developed, in which an SÀ S bond is formed by electrochemically oxidative coupling of SÀ H/SÀ H employing redox active NaI as mediator. The reactions are carried out in a simple undivided cell under constant current condition at room temperature and complete in 1.3 h to afford a series of diaciddisulfides with up to 97 % yields.

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Section: Introductionmentioning

confidence: 99%

Electrochemically Oxidative Coupling of S‐H/S‐H for S‐S Bond Formation: A Facile Approach to Diacid‐disulfides

et al. 2020

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“…Nitrothiophenol and pentafluorothiophenol, essential moieties widely used in pharmaceuticals and material science, were amenable to the reaction and furnished 4 j (61%) and 4 n (85%), respectively. The reactions of 2‐mercaptopyridine and 2‐quinolinethiol gave rise to adducts 4 o and 4 p in yields of 94% and 79%, respectively. The reaction also proceeded smoothly with heterocyclic thiols such as thiophene, benzoxazole, and furan to afford products 4 q , 4 r , and 4 s in yields of 88%, 73%, and 25%, respectively.…”

Section: Resultsmentioning

confidence: 99%

Efficient Synthesis of Sulfenamides through Mitsunobu‐type Coupling Reaction of Thiols with Amines using Dibenzyl Azodicarboxylate

Ryu

2020

Asian J Org Chem

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SÀ H activation reaction of thiols employing dibenzyl azodicarboxylate (DBAD) has been developed for the preparation of sulfenamides. The dehydrogenation of thiols and amines under these reaction conditions involved the formation of dibenzyl hydrazine-1,2-dicarboxylate (5 a), which led to the SÀ N bond formation reaction. The reaction proceeds efficiently with the release of 5 a and affords various sulfenamides in good to excellent yields.[a] S.

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“…The reduction is presumed to take place at the tetrazine ring as described in the literature. 39 , 40 The reduction can be reversed sluggishly, but spontaneously, back to the original oxidized tetrazine form. 38 The proposed reduced dihydrotetrazine SiFA–H 2 Tz was detected as two distinctly separated isomers with a percentage of ( E )-SiFA–H 2 Tz 89 ± 7% ( n = 2).…”

Section: Resultsmentioning

confidence: 99%

Metabolism of a Bioorthogonal PET Tracer Candidate [¹⁹F/¹⁸F]SiFA-Tetrazine in Mouse Liver Microsomes: Biotransformation Pathways and Defluorination Investigated by UHPLC-HRMS

et al. 2020

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Organofluorosilicon based 18 F-radiolabeling is an efficient method for incorporating fluorine-18 into 18 F-radiopharmaceuticals for positron emission tomography (PET) by 19 F/ 18 F isotopic exchange (IE). The first PET radiopharmaceutical, 18 F-SiFA lin -TATE, radiolabeled with a silicon-based [ 18 F]fluoride acceptor (SiFA), namely, a para-substituted di- tert -butyl[ 18 F]fluorosilylbenzene, has entered clinical trials, and is paving the way for other potential [ 18 F]SiFA-labeled radiopharmaceuticals for diagnostic use. In this study, we report the in vitro metabolism of an oxime-linked SiFA tetrazine (SiFA–Tz), a new PET-radiotracer candidate, recently evaluated for pretargeted PET imaging and macromolecule labeling. Metabolism of SiFA–Tz was studied in mouse liver microsomes (MLM) for elucidating its major biotransformation pathways. Nontargeted screening by ultrahigh performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS) was utilized for detection of unknown metabolites. The oxime bond between the SiFA and Tz groups forms two geometric ( E / Z ) isomers, which underwent the same biotransformations, but unexpectedly with different kinetics. In total, nine proposed metabolites of SiFA–Tz from phase I and II reactions were detected, five of which were defluorinated in MLMs, elucidating the metabolic pathway leading to previously reported defluorination of [ 18 F]SiFA–Tz in vivo . Based on the HRMS studies a biotransformation pathway is proposed: hydroxylation (+O) to tert -butyl group adjacent to the silicon, followed by oxidative defluorination (+OH/-F) cleaving the fluorine off the silicon. Interestingly, eight proposed metabolites of a reduced dihydrotetrazine analogue, SiFA–H 2 Tz, from phase I and II reactions were additionally detected. To the best of our knowledge, this is the first reported comprehensive investigation of enzyme mediated metabolic pathway of tetrazines and para-substituted di- tert -butylfluorosilylbenzene fluoride acceptors, providing novel structural information on the biotransformation and fragmentation patterns of radiotracers bearing these structural motifs. By investigating the metabolism preceding defluorination, structurally optimized new SiFA compounds can be designed for expanding the portfolio of efficient 19 F/ 18 F isotopic exchange labeling probes for PET imaging.

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3,6-Di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) mediated metal-free mild oxidation of thiols to disulfides in aqueous medium

Abstract: A wide range of aromatic, aliphatic, and heterocyclic thiophenols are converted to the corresponding disulfides by a highly efficient metal free oxidation under neutral conditions.

Cited by 40 publications

References 63 publications

Electrochemically Oxidative Coupling of S‐H/S‐H for S‐S Bond Formation: A Facile Approach to Diacid‐disulfides

Electrochemically Oxidative Coupling of S‐H/S‐H for S‐S Bond Formation: A Facile Approach to Diacid‐disulfides

Efficient Synthesis of Sulfenamides through Mitsunobu‐type Coupling Reaction of Thiols with Amines using Dibenzyl Azodicarboxylate

Metabolism of a Bioorthogonal PET Tracer Candidate [¹⁹F/¹⁸F]SiFA-Tetrazine in Mouse Liver Microsomes: Biotransformation Pathways and Defluorination Investigated by UHPLC-HRMS

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3,6-Di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) mediated metal-free mild oxidation of thiols to disulfides in aqueous medium

Abstract: A wide range of aromatic, aliphatic, and heterocyclic thiophenols are converted to the corresponding disulfides by a highly efficient metal free oxidation under neutral conditions.

Cited by 40 publications

References 63 publications

Electrochemically Oxidative Coupling of S‐H/S‐H for S‐S Bond Formation: A Facile Approach to Diacid‐disulfides

Electrochemically Oxidative Coupling of S‐H/S‐H for S‐S Bond Formation: A Facile Approach to Diacid‐disulfides

Efficient Synthesis of Sulfenamides through Mitsunobu‐type Coupling Reaction of Thiols with Amines using Dibenzyl Azodicarboxylate

Metabolism of a Bioorthogonal PET Tracer Candidate [19F/18F]SiFA-Tetrazine in Mouse Liver Microsomes: Biotransformation Pathways and Defluorination Investigated by UHPLC-HRMS

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Metabolism of a Bioorthogonal PET Tracer Candidate [¹⁹F/¹⁸F]SiFA-Tetrazine in Mouse Liver Microsomes: Biotransformation Pathways and Defluorination Investigated by UHPLC-HRMS