Kinetics and stereochemistry of nucleophilic reactions of phenacyl halide oximes

Smith, Jerry H.; Heidema, John H.; Kaiser, E. T.

doi:10.1021/ja00781a075

Cited by 31 publications

(9 citation statements)

References 3 publications

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“…In 2014, we reported an efficient synthesis of oxazoles from PBu 3 , N -acylimines, and acyl chlorides via the Wittig reaction (Scheme a) . To continue our effort toward the development of novel intramolecular Wittig strategies, we envisioned that the E/Z mixture of α-halohydrazones/ketoximes when treated with phosphine generate Z -phosphonium salts exclusively via transient conjugated azo-/nitrosoalkenes, and thus generated phosphonium salts could be transformed into bioactive pyrazoles/isoxazoles via a tandem acylation/Wittig reaction sequence (Scheme b). In this context, we report a metal-free approach for the synthesis of trisubstituted pyrazoles and disubstituted isoxazoles.…”

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confidence: 99%

An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes

et al. 2019

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α-Halohydrazones/ketoximes are transformed into trisubstituted pyrazoles/disubstituted isoxazoles by treatment with phosphine, acyl chloride, and a base. Mechanistic investigations revealed the in situ formation of azo/nitroso olefin intermediates which underwent a tandem phospha-Michael/N-or O-acylation/intramolecular Wittig reaction to afford the heteroarenes in moderate to good yields. Further, proper functionalization of α-haloketoximes and a change of conditions allowed the chemoselective synthesis of chromenone-oximes as well as rearranged isoxazoles, thereby realizing a diversity-oriented synthesis.

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mentioning

confidence: 99%

An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes

et al. 2019

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“…The CNDO/2-SCF-MO calculations 77 for a hypothetical structure of aldehyde 39 demonstrated the possibility of this binding. The X-ray diffraction 78 and 15 N NMR spectroscopy 79 data for 1,2,3-thiadiazole 40 also imply a thiapentalene character of this structure.…”

Section: Structure and Physical Properties Of Nitrosoalkenesmentioning

confidence: 78%

“…Reactions with both bromo oximes give anti-a-morpholino oxime 60. 15 Presumably, bromo oximes undergo fast deprotonation and then eliminate Br 7 in the rate-determining step yielding the intermediate 1-nitroso-1-phenylethylene 1l. Morpholine adds to the nitrosoalkene 1l, which occurs in the transoid conformation.…”

Section: Reactions With Nucleophilesmentioning

confidence: 99%

Conjugated nitrosoalkenes

Lyapkalo¹,

Ioffe²

1998

Russ. Chem. Rev.

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Published data on the preparation, structure, physical and chemical properties, and reactivity of nitrosoalkenes are described systematically. The influence of the structure and stereoelectronic effects of substituents at the double bond on the stability of nitrosoalkenes is analysed. Primary attention is paid to concerted cycloaddition of nitrosoalkenes to miscellaneous multiple bonds, in particular, to the problems of regio-, stereo-, and enantioselectivity of [4 + 2]-cycloaddition of nitrosoalkenes to alkenes. The bibliography includes 183 references.

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“…The intermediate of Fig. 1(b) has been identified (GC-MS, NMR and compared with a standard see supplementary materials) as APO-TFA and AcA-TFA, while acetophenone derive from APO hydrolysis due to the reaction of the protonated form of APO (APO pK a = 2.52, TFA pK a ≈ 0.47) with the water deriving from the formation of the APO-TFA (esterification), or from a secondary reaction path already described in a previous paper [27][28][29][36][37][38].…”

Section: Time Vs Concentrations Profile Of the Tfa Catalyzedmentioning

confidence: 90%

Beckmann rearrangement of acetophenone oximes to the corresponding amides organo-catalyzed by trifluoroacetic acid for sustainable NSAIDs synthesis

Quartarone

Rancan

Ronchin

et al. 2014

Applied Catalysis A: General

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The Beckmann rearrangement of acetophenone oximes to the corresponding amides (4hydroxyacetophenone oxime to N-acetyl-4-hydroxyacetanilide and acetophenone oxime to N-phenylacetamide) is investigated by using trifluoroacetic acid (TFA) as catalyst. The reaction occurs either in the presence or in the absence of a suitable solvent. High selectivity and practically quantitative yield to amide is achieved in both cases at TFA/substrate > 3. Both TFA and the solvent (whenever present) could be easily reused by distillation since no protonation of amides occurs. The reaction proceeds via a multistep reaction path and the role of TFA is related not only to its acidity but also mainly to its ability on forming reactive trifluoroacetylated intermediates. In particular, the highly reactive trifluoroacetylated amide is actually the effective catalyst. Finally, a likely reaction path is proposed.

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Kinetics and stereochemistry of nucleophilic reactions of phenacyl halide oximes

Cited by 31 publications

References 3 publications

An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes

An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes

Conjugated nitrosoalkenes

Beckmann rearrangement of acetophenone oximes to the corresponding amides organo-catalyzed by trifluoroacetic acid for sustainable NSAIDs synthesis

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