Nitropyridyl isocyanates

Holt, Jarle; Andreassen, Trygve; Bakke, Jan M.; Fiksdahl, Anne

doi:10.1002/jhet.5570420213

Cited by 35 publications

(28 citation statements)

References 13 publications

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“…Strong characteristic azide IR absorption frequencies (2155, 2180 cm -1 ) also supported cycloreversion. A similar observation was made for tetrazolinone (10) (Scheme 5) when left in solution, affording 5-amino-2-nitropyridine (13) and the urea compound (12) as decomposition products [2], as shown by 1 H NMR. The urea compound (12) is supposed to be a condensation product of isocyanate 9 formed by cycloreversion and the amine 13, the isocyanate hydrolysis product.…”

Section: Resultssupporting

confidence: 54%

“…(14) and isocyanates 7 and 9, respectively (Scheme 6). Isocyanate 7 and 9 were formed in situ in dry benzene from the corresponding acyl azide as previously described [2]. The cycloaddition reaction mixtures were refluxed for five days.…”

Section: Resultsmentioning

confidence: 99%

“…3-Nitropyridin-4-yl isocyanate (7) was prepared in situ in dry benzene from the corresponding acyl azide through a Curtius rearrangement [2]. The carbonyl azide precursor was made in dry diethyl ether through diazotization of the corresponding carbonyl hydrazide.…”

Section: Resultsmentioning

confidence: 99%

“…Heterocyclic isocyanates are, however, mostly not suitable for syntheses due to their instability. We have recently been successful preparing the first stable nitropyridyl isocyanates [2]. The stability is caused by the electron-withdrawing effect of the nitro group.…”

Section: Introductionmentioning

confidence: 99%

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Nitropyridyl isocyanates in 1,3‐dipolar cycloaddition reactions

Holt

Fiksdahl

2007

Journal of Heterocyclic Chem

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The reactivity of 3-nitro-4-pyridyl isocyanate (7) and 5-nitropyridin-2-yl isocyanate (9) in 1,3-dipolar cycloaddition reactions with azides and pyridine N-oxides has been investigated. 1,3-Dipolar cycloaddition to trimethylsilylazide (TMSA) afforded the respective tetrazolinones, 1-(3-nitropyridin-4-yl)-1H-tetrazol-5(4H)one (8, 50 %) and 1-(5-nitropyridin-2-yl)-1H-tetrazol-5(4H)one (11, 64 %). Respectively, 1,3-dipolar cycloaddition of nitropyridyl isocyanates 7 and 9 to 3,5-dimethylpyridine N-oxide (14), 3-methylpyridine N-oxide (21) and pyridine N-oxide (22) gave the substituted amines, 3,5-dimethyl-N-(3-nitropyridin-4-yl)pyridin-2-amine (17), 3,5-dimethyl-N-(5-nitropyridin-2-yl)pyridin-2-amine (20), N-(5-nitropyridin-2-yl)pyridin-2-amine (24), 5-methyl-N-(5-nitropyridin-2-yl)pyridin-2-amine (23) and 3-methyl-N-(5-nitropyridin-2-yl)pyridin-2-amine (25) in 65 -80 % yield, obtained by cycloaddition, rearrangement and decarboxylation. The results demonstrate that the nitropyridyl isocyanates (7,9) readily undergo 1,3-dipolar cyloaddition reactions similar to phenyl isocyanates.

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Section: Resultssupporting

confidence: 54%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nitropyridyl isocyanates in 1,3‐dipolar cycloaddition reactions

Holt

Fiksdahl

2007

Journal of Heterocyclic Chem

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“…13) All other reagents and solvents were of analytical grade. Derivatization of Oxosteroids with HP or HMP To a solution of oxosteroid in ethanol (30 ml), a freshly prepared solution of HP or HMP (10 mg) in ethanol (50 ml) containing 25 mg of trifluoroacetic acid was added, and the mixture was maintained at 60°C for 1 h. After removal of the solvents, the product was dissolved in methanol-10 mM ammonium formate (1 : 1, v/v), an aliquot of which was subjected to LC-MS(-MS).…”

Section: Methodsmentioning

confidence: 99%

Alternative Procedure for Charged Derivatization to Enhance Detection Responses of Steroids in Electrospray Ionization-MS

Higashi

Nishio

Hayashi

et al. 2007

CHEMICAL & PHARMACEUTICAL BULLETIN

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A derivatization procedure has been examined to enhance the electrospray ionization (ESI)-MS detectabilities of steroids that charged derivatization is not suitable for. The derivatization procedure with 2-hydrazinopyridine or isonicotinoyl azide was very effective for the sensitive detection of di-oxosteroids or di-hydroxysteroids, respectively, and the detection limits of the resulting derivatives were as low as about 2 fmol. The derivatives also provided intense characteristic product ions in the MS-MS, which are expected to be usable for the selected reaction monitoring mode.

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Studies on neurosteroids XXIV. Determination of neuroactive androgens, androsterone and 5α‐androstane‐3α,17β‐diol, in rat brain and serum using liquid chromatography–tandem mass spectrometry

Higashi

Yokoi

Nagura

et al. 2008

Biomedical Chromatography

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The development and validation of liquid chromatography-electrospray ionization-tandem mass spectrometric (LC-ESI-MS/MS) methods that enable the quantification of neuroactive androgens, androsterone (5alpha-androstan-3alpha-ol-17-one, 3alpha,5alpha-A) and 5alpha-androstane-3alpha,17beta-diol (3alpha,5alpha-Adiol), in the rat brain and serum are presented. The androgens were extracted with methanol-acetic acid, purified using solid-phase extraction cartridges, derivatized with an ESI-active reagent, isonicotinoyl azide (INA), and then subjected to LC-ESI-MS/MS. The quantifications were based on selected reaction monitoring mode using the characteristic transitions of the INA derivatives. The methods allowed the reproducible and accurate quantification of the brain and serum neuroactive androgens using a 100 mg or 100 microL sample; the intra- and inter-assay relative standard deviations were below 3.6%, and the percentage accuracy values were 97.1-103.7% for both androgens. The animal study using the methods suggests that most of 3alpha,5alpha-Adiol found in the brain is derived from the periphery, while 3alpha,5alpha-A is not only transported from the periphery into the brain, but also synthesized in the brain by the oxidation of 3alpha,5alpha-Adiol. The androgens in the rats intraperitoneally administered finasteride, a 5alpha-reductatse inhibitor, were also measured; this treatment significantly reduced the brain 3alpha,5alpha-A and 3alpha,5alpha-Adiol levels and increased only the brain level of androstenedione, the precursor of 3alpha,5alpha-A.

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Nitropyridyl isocyanates

Abstract: For Abstract see ChemInform Abstract in Full Text.

Cited by 35 publications

References 13 publications

Nitropyridyl isocyanates in 1,3‐dipolar cycloaddition reactions

Nitropyridyl isocyanates in 1,3‐dipolar cycloaddition reactions

Alternative Procedure for Charged Derivatization to Enhance Detection Responses of Steroids in Electrospray Ionization-MS

Studies on neurosteroids XXIV. Determination of neuroactive androgens, androsterone and 5α‐androstane‐3α,17β‐diol, in rat brain and serum using liquid chromatography–tandem mass spectrometry

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