Methoxy(2‐pyridyl)ketene

Andersen, Heidi Gade; Bednarek, Pawel; Wentrup, Curt

doi:10.1002/poc.628

Cited by 9 publications

(13 citation statements)

References 9 publications

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“…When methyl(2-pyridyl)carbene is generated directly by FVP of 3-methyltetrazolo[1,5- a ]pyridine 87 , 2-vinylpyridine 84b is the exclusive product, formed in 100% yield at 500 °C/0.15 hPa; , i.e., the 1,2-H shift is much faster than the carbene–nitrene rearrangement (Scheme ). The carbene–nitrene rearrangement can also be arrested by an acetyl group in 3-acetyltriazolo[1,5- a ]pyridine 88 ; the 2-pyridyldiazoketone or carbene formed undergoes a Wolff rearrangement to methyl(2-pyridyl)ketene …”

Section: Azidesmentioning

confidence: 99%

Flash Vacuum Pyrolysis of Azides, Triazoles, and Tetrazoles

2017

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Flash vacuum pyrolysis (FVP) of azides is an extremely valuable method of generating nitrenes and studying their thermal rearrangements. The nitrenes can in many cases be isolated in low-temperature matrices and observed spectroscopically. NH and methyl, alkyl, aralkyl, vinyl, cyano, aryl and N-heteroaryl, acyl, carbamoyl, alkoxycarbonyl, imidoyl, boryl, silyl, phosphonyl, and sulfonyl nitrenes are included. FVP of triazoloazines generates diazomethylazines and azinylcarbenes, which often rearrange to the energetically more stable arylnitrenes. N elimination from monocyclic 1,2,3-triazoles can generate iminocarbenes, 1H-azirines, ketenimines, and cyclization products, and 1,2,4-triazoles are precursors of nitrile ylides. Benzotriazoles are preparatively useful precursors of cyanocyclopentadienes, carbazoles, and aza-analogues. FVP of 5-aryltetrazoles can result in double N elimination with formation of arylcarbenes or of heteroarylcarbenes, which again rearrange to arylnitrenes. Many 5-substituted and 2,5-disubstituted tetrazoles are excellent precursors of nitrile imines (propargylic, allenic, or carbenic), which are isolable at low temperatures in some cases (e.g., aryl- and silylnitrile imines) or rearrange to carbodiimides. 1,5-Disubstituted tetrazoles are precursors of imidoylnitrenes, which also rearrange to carbodiimides or add intramolecularly to aryl substituents to yield indazoles and related compounds. Where relevant for the mechanistic understanding, pyrolysis under flow conditions or in solution or the solid state will be mentioned. Results of photolysis reactions and computational chemistry complementing the FVP results will also be mentioned in several places.

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Section: Azidesmentioning

confidence: 99%

Flash Vacuum Pyrolysis of Azides, Triazoles, and Tetrazoles

2017

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“…However, in the case of ester derivative 153a , ketene 158 was observed as the major product, likely through an intramolecular C–H insertion of OCH 3 via singlet carbene intermediate 155a followed by fragmentation of the formed propiolactone 157 into ketene 158 and formaldehyde 159 . The latter observation was supported by DFT calculations . The Tidwell group reported formation of the ylide 160 upon photolysis of 3-pyridyl-substituted pyridotriazoles (Scheme b).…”

Section: Photolysis Of Pyridotriazolesmentioning

confidence: 73%

“…The latter observation was supported by DFT calculations. 55 The Tidwell group reported formation of the ylide 160 upon photolysis of 3-pyridyl-substituted pyridotriazoles 56 (Scheme 38b). The Zimmerman group utilized the UV-generated carbene intermediate from pyridotriazole 161 for cyclopropanation of cyclopentadiene 162, 57 which was employed as solvent to give a mixture of exo-and endo products 163 in moderate yield (Scheme 39).…”

Section: Miscellaneous Reactions Of Pyridotriazolesmentioning

confidence: 99%

Denitrogenative Transformations of Pyridotriazoles and Related Compounds: Synthesis of N-Containing Heterocyclic Compounds and Beyond

2020

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The high demand for new and efficient routes toward synthesis of nitrogencontaining heterocyclic scaffolds has inspired organic chemists to discover several methodologies over recent years. This Perspective highlights one standout approach, which involves the use of pyridotriazoles and related compounds in denitrogenative transformations. Readily available pyridotriazoles undergo ring−chain isomerization to produce uniquely reactive α-diazoimines. Such reactivity, enabled by metal catalysts, additives, or visible-light irradiation, can be applied in transannulation, insertion, cyclopropanation, and many other transformations.

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“…However, the photolysis of the same triazole results in the formation of formaldehyde and 2-pyridylketene 132 predominantly in the s-E form (Scheme 35). 129 This same compound can be obtained by the photolysis of the matrix isolated 2-diazoacetylpyridine or interconverted to the s-Z form under photochemical irradiation. 130 …”

Section: Decarbonylationmentioning

confidence: 98%