Bromination of pyridines. II. Bromination of Aminopicolines

Dunn, A. D.; Currie, A.; Hayes, L. E.

doi:10.1002/prac.19893310302

Cited by 17 publications

(6 citation statements)

References 6 publications

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“…As precursor for subsequent polycondensation the 2,5‐dibrominated pyridine M1 (Scheme ) was prepared in five steps starting from 6‐amino‐2‐picoline ( 5 ). Bromination of 5 furnished the 3‐bromopyridine 6 , which was converted into 3,6‐dibromo‐2‐picoline ( 7 ) via a Sandmeyer‐type reaction . Sidechain bromination under Wohl–Ziegler conditions and further reaction with triphenylphosphine then gave the phosphonium salt 8 .…”

Section: Resultsmentioning

confidence: 99%

Preparation of Head‐to‐Tail Regioregular 6‐(1‐Alkenyl)‐Functionalized Poly(pyridine‐2,5‐diyl) and its Post‐Functionalization via Hydroboration

Grandl

Pammer

2015

Macro Chemistry & Physics

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In this work, the preparation of head-to-tail regioregular poly(6-(1-tridecenyl)-pyridine-2,5-diyl) ( PPy ) and its post-functionalization via hydroboration is described. PPy has been prepared via Kumada-coupling polycondensation with different catalytic systems. Numberaverage molecular weights of up to M n = 14.7 kDa (PDI = 2.0, DP n = 60) can be obtained, as determined by gel permeation chromatography relative to polystyrene standards. PPy has been characterized by MALDI-TOF MS, optical spectroscopy, and cyclic voltammetry. The regioregularity of the material is confi rmed by comparison with a head-to-head-tail-to-tail regioregular polybipyridine ( PBPy , M n = 14.0 kDa, PDI = 1.5, DP n = 29). The 1-alkenyl-substituents in PPy have been introduced to provide functional groups for post-functionalization. Herein, it is also demonstrated that these internal double-bonds are suffi ciently reactive to allow for hydroboration with 9 H -borabicyclo[3.3.1]nonane (9 H -BBN), to furnish an intermediate borylated polymer ( PPyHB ). Treatment of PPyHB with strong acids, and characterization of the deborylated polymer PPyH 2 proves quantitative conversion of the precursor polymer.

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Section: Resultsmentioning

confidence: 99%

Preparation of Head‐to‐Tail Regioregular 6‐(1‐Alkenyl)‐Functionalized Poly(pyridine‐2,5‐diyl) and its Post‐Functionalization via Hydroboration

Grandl

Pammer

2015

Macro Chemistry & Physics

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“…Commercially available 2‐amino‐3‐hydroxypyridine was reacted with 1‐bromo‐2‐(2‐methoxyethoxy)ethane in 40% aqueous NaOH with the aid of a phase‐transfer catalyst, Adogen464,14 at 50 °C, resulting in selective alkylation of the hydroxyl group of 2‐amino‐3‐hydroxypyridine to afford 2 . The 5‐position of 2 was selectively brominated with 2,4,4,6‐tetrabromo‐2,5‐cyclohexadienone 15. The amino group of the obtained 3 was converted to bromine by treatment with Br 2 , HBr, and NaNO 2 to yield the monomer precursor 1 .…”

Section: Resultsmentioning

confidence: 99%

“…The 5-position of 2 was selectively brominated with 2,4,4,6-tetrabromo-2,5-cyclohexadienone. 15 The amino group of the obtained 3 was converted to bromine by treatment with Br 2 , HBr, and NaNO 2 to yield the monomer precursor 1.…”

Section: Synthesis Of Monomer Precursor and Generation Of Grignard-tymentioning

confidence: 99%

Synthesis of novel blue‐light‐emitting polypyridine

Nanashima

Yokoyama

Yokozawa

2012

J. Polym. Sci. A Polym. Chem.

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A new regioregular head‐to‐tail (HT)‐type polypyridine with methoxyethoxyethoxy (MEEO) side chains, HT‐PMEEOPy, was synthesized by means of Kumada‐Tamao coupling polymerization of a Grignard monomer with a Ni catalyst. Although the polymer was precipitated in THF during polymerization, multiangle laser light scattering (MALLS) analysis indicated that the weight‐average molecular weight (Mw) was about 25,000. The HT content in the polymer was 95%. A solution of HT‐PMEEOPy in CHCl3 was found to emit a strong blue light when the solution was irradiated with UV light; the UV‐vis absorption maximum (λmax) and photoluminescence maximum (λmax em) were at 392 and 460 nm, respectively. To clarify the effect of regioregularity of PMEEOPy on the photoluminescence, head‐to‐head (HH) PMEEOPy was synthesized by means of Yamamoto coupling polymerization. The photoluminescence of HH‐PMEEOPy (λmax = 330 nm, λmax em = 414 nm) was weaker than that of HT‐PMEEOPy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

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“…The lack of selectivity in the bromination step, above, was readily circumvented when a commercial source for 6-amino-5-bromo-2-picoline ( 12 ) was identified; however, this new starting point had a deleterious effect on the subsequent permanganate oxidation (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Optimisation of Permanganate Oxidation and Suzuki−Miyaura Coupling Steps in the Synthesis of a Na_v1.8 Sodium Channel Modulator

Fray

Gillmore

Glossop

et al. 2009

Org. Process Res. Dev.

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The development is described of a viable kilo-scale synthesis of the Na v 1.8 sodium channel modulator, N-methyl-6-amino-5-(2,3,5-trichlorophenyl)pyridine-2-carboxamide (PF-1247324) in five steps, starting from 6-amino-5-bromo-2-picoline, in 33% overall yield. Two key steps required significant optimisation to improve yield and reproducibility. Oxidation of 6-acetamido-5-bromo-2-methylpyridine by permanganate to give the corresponding carboxylic acid derivative was improved by adding potassium dihydrogen phosphate, which moderated the reaction mixture pH and doubled the yield. The potassium fluoride-promoted Suzuki-Miyaura coupling between 2,4,5-trichlorophenylboronic acid and methyl 6-amino-5-bromopyridine-2-carboxylate, catalysed by tri(tert-butyl)phosphinepalladium (0), proceeded reliably to completion at room temperature in high yield when water was added. Anhydrous reaction mixtures reacted much more slowly, and 'wet' mixtures led to significant protodeboronation in the absence of sufficient active catalyst. In the final step, amidation of the ester with methylamine gave PF-1247324.

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Bromination of pyridines. II. Bromination of Aminopicolines

Abstract: The bromination of all ten possible aminopicolines 1–10 was investigated. In general, the major brominated product was that corresponding to electrophilic attack at the sites para or ortho to the amino group.

Cited by 17 publications

References 6 publications

Preparation of Head‐to‐Tail Regioregular 6‐(1‐Alkenyl)‐Functionalized Poly(pyridine‐2,5‐diyl) and its Post‐Functionalization via Hydroboration

Preparation of Head‐to‐Tail Regioregular 6‐(1‐Alkenyl)‐Functionalized Poly(pyridine‐2,5‐diyl) and its Post‐Functionalization via Hydroboration

Synthesis of novel blue‐light‐emitting polypyridine

Optimisation of Permanganate Oxidation and Suzuki−Miyaura Coupling Steps in the Synthesis of a Na_v1.8 Sodium Channel Modulator

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Bromination of pyridines. II. Bromination of Aminopicolines

Abstract: The bromination of all ten possible aminopicolines 1–10 was investigated. In general, the major brominated product was that corresponding to electrophilic attack at the sites para or ortho to the amino group.

Cited by 17 publications

References 6 publications

Preparation of Head‐to‐Tail Regioregular 6‐(1‐Alkenyl)‐Functionalized Poly(pyridine‐2,5‐diyl) and its Post‐Functionalization via Hydroboration

Preparation of Head‐to‐Tail Regioregular 6‐(1‐Alkenyl)‐Functionalized Poly(pyridine‐2,5‐diyl) and its Post‐Functionalization via Hydroboration

Synthesis of novel blue‐light‐emitting polypyridine

Optimisation of Permanganate Oxidation and Suzuki−Miyaura Coupling Steps in the Synthesis of a Nav1.8 Sodium Channel Modulator

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Optimisation of Permanganate Oxidation and Suzuki−Miyaura Coupling Steps in the Synthesis of a Na_v1.8 Sodium Channel Modulator