The Rearrangement of Substituted Pyridine N-Oxides with Acetic Anhydride<sup>1.2</sup>

Boekelheide, V.; Lehn, W. L.

doi:10.1021/jo01061a037

Cited by 44 publications

(13 citation statements)

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“…Boekelheide rearrangement on 3a using trifluoroacetic anhydride resulted in 68% of pyridinone 9. [17] Closely related 6-methylated substrate 3m gave 77% of the picolinyl alcohol 10. [18] Amination was possible via reaction of 3a with Ts2O and t-butylamine followed by de-t-butylation with TFA (11, 67%).…”

Section: Resultsmentioning

confidence: 99%

Copper‐Catalyzed Aerobic Oxygenation of Benzylpyridine N‐Oxides and Subsequent Post‐Functionalization

et al. 2017

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A copper-catalyzed aerobic oxidation of benzylpyridine N-oxides is reported. The N-oxide moiety acts as a built-in activator for the benzylic methylene oxidation, without requirement of additives. Reaction conditions were identified which suppress undesired benzoylpyridine formation via N-deoxygenation involving intermolecular oxygen transfer. The versatility of the Noxide group of the benzoylpyridine N-oxide reaction products for post-functionalization of the pyridine ring is demonstrated through efficient C-C, C-N, C-O and C-Cl bond forming procedures, with both nucleophiles and electrophiles. Finally, the applicability of the new synthetic methodology is demonstrated in an alternative route towards the anti-histaminic drug Acrivastine via three consecutive N-oxide activated C-H functionalization processes, starting from picoline N-oxide.

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Section: Resultsmentioning

confidence: 99%

Copper‐Catalyzed Aerobic Oxygenation of Benzylpyridine N‐Oxides and Subsequent Post‐Functionalization

et al. 2017

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“…The methods of Buchi et al (1947) and Baumler et al (1951) were attempted but were not successful. A synthesis modified from that of Boekelheide & Lehn (1961) did, however, yield the required material. Isonicotinate (2g) was refluxed with methanol (10ml) and conc.…”

Section: Chemicalsmentioning

confidence: 98%

The bacterial oxidation of N-methylisonicotinate, a photolytic product of Paraquat

Orpin

Knight

1972

Biochemical Journal

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Two bacteria have been isolated that are capable of oxidizing N-methylisonicotinate, a photodegradation product of Paraquat (1.1'-dimethyl-4,4'-bipyridylium ion). N-Methylisonicotinate-grown cells of strain 4C1, a Gram-positive rod, oxidized 2-hydroxy-N-methylisonicotinate without lag. Cell-free extracts of these cells converted 2-hydroxyisonicotinate into 2,6-dihydroxyisonicotinate; the reaction did not require molecular oxygen. Maleamate was deamidated and maleate isomerized to fumarate by soluble enzyme systems. [(14)C]Formaldehyde was isolated as the dimedone derivative from the supernatant of a cell suspension oxidizing N-[(14)C]methylisonicotinate, and no [(14)C]-methylamine was detected. Whole cells incubated with N-methyl[carboxy-(14)C]isonicotinate released 95% of the radioactivity as (14)CO(2). The second bacterium, strain 4C2, a Gram-negative rod, did not oxidize any of the mono- or di-hydroxypyridines or their N-methyl derivatives that were available or could be synthesized; nor did cell-free extracts oxidize any of these compounds. Methylamine was oxidized by whole cells without lag; cell-free extracts converted methylamine into formaldehyde when a soluble enzyme system requiring an electron acceptor was used; formaldehyde was oxidized to formate and formate to CO(2) by enzyme systems requiring NAD(+).

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“…Syntheses. The following materials were synthesized by the methods of the respective authors; picolinamide and isonicotinamide (pyridine-4-carboxamide) (Vogel, 1956); 3-hydroxypicolinate (Sheehan, 1966); 5-hydroxypicolinate (Duesel & Scudi, 1949); 6-hydroxypicolinate (Newbold & Spring, 1949;Boekelheide & Lehn, 1961); 2,4dihydroxypyridine (von Schickh et al, 1936); 2,5dihydroxypyridine (Behrman & Pitt, 1958); fumaramate (Greiss, 1879).…”

Section: Chemicalsmentioning

confidence: 99%

The bacterial oxidation of picolinamide, a photolytic product of Diquat

Orpin

Knight

1972

Biochemical Journal

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The pathway of oxidation of picolinamide (pyridine-2-carboxamide) by a Gram-negative rod has been elucidated. Under conditions of high pH, restricted aeration and high substrate concentration, whole cells released 2,5-dihydroxypyridine into culture supernatants. Sodium arsenite at 5mm caused whole cells to accumulate 6-hydroxypicolinate, and, at 1mm, pyruvate, in culture media. Whole cells oxidized picolinamide, picolinate, 6-hydroxypicolinate, maleamate and maleate without lag. Cell-free extracts converted picolinamide into picolinate, and hydroxylated picolinate to 6-hydroxypicolinate. The hydroxylase was particulate, but could be solubilized by ultrasonic treatment; it required NAD(+) for activity, and did not require molecular oxygen. 2,5-Dihydroxypyridine was converted into maleamate and formate by an oxygenase requiring GSH and Fe(2+). Maleamate was deamidated to maleate, and maleate isomerized to fumarate, by unsupplemented extracts.

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The Rearrangement of Substituted Pyridine N-Oxides with Acetic Anhydride^1.2

Cited by 44 publications

References 1 publication

Copper‐Catalyzed Aerobic Oxygenation of Benzylpyridine N‐Oxides and Subsequent Post‐Functionalization

Copper‐Catalyzed Aerobic Oxygenation of Benzylpyridine N‐Oxides and Subsequent Post‐Functionalization

The bacterial oxidation of N-methylisonicotinate, a photolytic product of Paraquat

The bacterial oxidation of picolinamide, a photolytic product of Diquat

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The Rearrangement of Substituted Pyridine N-Oxides with Acetic Anhydride1.2

Cited by 44 publications

References 1 publication

Copper‐Catalyzed Aerobic Oxygenation of Benzylpyridine N‐Oxides and Subsequent Post‐Functionalization

Copper‐Catalyzed Aerobic Oxygenation of Benzylpyridine N‐Oxides and Subsequent Post‐Functionalization

The bacterial oxidation of N-methylisonicotinate, a photolytic product of Paraquat

The bacterial oxidation of picolinamide, a photolytic product of Diquat

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The Rearrangement of Substituted Pyridine N-Oxides with Acetic Anhydride^1.2