Reactions of Diazo Compounds with Nitroölefins. III. Group Migrations in the Decomposition of Nitropyrazolines

Parham, William E.; Hasek, William R.

doi:10.1021/ja01632a049

Cited by 29 publications

(6 citation statements)

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“…It should be highlighted, however, that any cases of this type of decomposition of nitropyrazoline systems had not been previously described. Some of these heterocycles decomposed under mild conditions, but via completely different mechanisms [ 28 – 32 ]. Alternatively, it may be assumed that in the first reaction stage, a zwitterionic intermediate I is formed.…”

Section: Resultsmentioning

confidence: 99%

Unexpected course of reaction between (E)-2-aryl-1-cyano-1-nitroethenes and diazafluorene: why is there no 1,3-dipolar cycloaddition?

et al. 2017

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Reactions between (E)-2-aryl-1-cyano-1-nitroethenes and diazafluorene lead to acyclic 2,3-diazabuta-1,3-diene derivatives, instead of the expected pyrazoline systems. DFT calculations suggest that this is a consequence of formation of zwitterionic structure in the first stage of the reaction. It must be noted that this is a specific property of the (E)-2-aryl-1-cyano-1-nitroethenes group, in contrast to most other conjugated nitroalkenes.Graphical abstract Electronic supplementary materialThe online version of this article (doi:10.1007/s00706-016-1893-5) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Unexpected course of reaction between (E)-2-aryl-1-cyano-1-nitroethenes and diazafluorene: why is there no 1,3-dipolar cycloaddition?

et al. 2017

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“…The group mentioned above also reported that diphenyl diazomethane and secondary nitroolefin 96 gave 5,5-diphenyl-3-nitro pyrazoline 97 , which rearrange as shown when treated with acids or bases to give 3-methyl-4,5-diphenyl-1 H -pyrazole 5 ( Scheme 41 ) [ 77 ].…”

Section: Synthesis Of Pyrazolesmentioning

confidence: 99%

Substituted Pyrazoles and Their Heteroannulated Analogs—Recent Syntheses and Biological Activities

et al. 2021

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Pyrazoles are considered privileged scaffolds in medicinal chemistry. Previous reviews have discussed the importance of pyrazoles and their biological activities; however, few have dealt with the chemistry and the biology of heteroannulated derivatives. Therefore, we focused our attention on recent topics, up until 2020, for the synthesis of pyrazoles, their heteroannulated derivatives, and their applications as biologically active moieties. Moreover, we focused on traditional procedures used in the synthesis of pyrazoles.

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“…To a stirred mixture of I 2 (90. (7), 113 (17), 100 (14), 89 (31), 77 (14), 75 (13), 74 (13), 73 (4), 69 (8), 63 (20), 51 (26).…”

Section: -Chloro-4-iodo-5-phenylisothiazolementioning

confidence: 99%

“…, 218 (12), 209 (7), 190 (13), 178 (10), 176 (10), 165 (28), 152 (7), 139 (4), 126 (6), 121 (4), 104 (8), 89 (8), 77 (12), 74 (9), 69…”

Section: -Amino-45-diphenylisothiazole 16unclassified

3,4,5-Triarylisothiazoles via C–C coupling chemistry

Christoforou

Koutentis

2007

Org. Biomol. Chem.

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The regiocontrolled preparation of triarylisothiazoles is presented. 3-Halo-5-phenylisothiazole-4-carbonitriles, 1 (hal=Cl) and 18 (hal=I), are converted into the corresponding 4-bromo derivatives 5 (3-hal=Cl) and 24 (3-hal=I) via a Hunsdiecker strategy while the 4-iodo analogues 7 (3-hal=Cl) and 22 (3-hal=I) are prepared via a Hoffmann and Sandmeyer strategy. Regioselective Suzuki, Stille and Negishi reactions occur at C-4 with both the 4-bromo- and 4-iodoisothiazoles 5 and 7 , the latter being more reactive than the former. 3-Iodoisothiazoles 22 and 24 fail to give regiocontrolled Suzuki, Stille or Negishi couplings, however, 4-bromo-3-iodo-5-phenylisothiazole 24 gives the regiospecific palladium catalysed Ullmann-type reaction product 3,3'-bi(4-bromo-5-phenylisothiazole) 25 . Alkali hydrolysis of 3-chloro-4,5-diphenylisothiazole 8 gives the 3-hydroxy analogue 12 which is converted into 3-bromo-4,5-diphenylisothiazole 13 with POBr(3). 3-Bromoisothiazole 13 reacts with phenylzinc chloride to give 3,4,5-triphenylisothiazole 17 but fails to undergo effective Suzuki or Stille couplings. 3,5-Diphenylisothiazole-4-carbonitrile 26 is converted into the 4-bromo- and 4-iodo-3,5-diphenylisothiazoles 30 and 34 both of which are effective for Suzuki and Stille couplings. A series of triarylisothiazoles are prepared in this manner and fully characterised.

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Reactions of Diazo Compounds with Nitroölefins. III. Group Migrations in the Decomposition of Nitropyrazolines

Cited by 29 publications

References 0 publications

Unexpected course of reaction between (E)-2-aryl-1-cyano-1-nitroethenes and diazafluorene: why is there no 1,3-dipolar cycloaddition?

Unexpected course of reaction between (E)-2-aryl-1-cyano-1-nitroethenes and diazafluorene: why is there no 1,3-dipolar cycloaddition?

Substituted Pyrazoles and Their Heteroannulated Analogs—Recent Syntheses and Biological Activities

3,4,5-Triarylisothiazoles via C–C coupling chemistry

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