A pathway to 3-(β-D-ribofuranosyl)-4-nitro-5-ethoxycarbonyl-isoxazoles, useful in the synthesis of pyrazofurin analogues

Deceuninck, Johnny A.; Buffel, Diederik K.; Hoornaert, Georges J.

doi:10.1016/0040-4039(80)80250-4

Cited by 14 publications

(5 citation statements)

References 6 publications

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“…50 Condensation of oximes of α-nitro ketones with dicarboxylic acid monochlorides also proceeds under mild conditions at room temperature and gives 4-nitroisoxazoles with various substituents (Scheme 5). [52][53][54][55] In some cases the O-acyl α-nitrooximes were isolated as intermediate products that participated in further cyclization only under heating with a base like triethylamine or pyridine. [52][53][54]56 Heterocyclization of O-acyl α-nitrooximes by treatment with aluminum(III) oxide has also been reported.…”

Section: Condensations Of α-Nitro Ketones or Their Oximesmentioning

confidence: 99%

“…[52][53][54][55] In some cases the O-acyl α-nitrooximes were isolated as intermediate products that participated in further cyclization only under heating with a base like triethylamine or pyridine. [52][53][54]56 Heterocyclization of O-acyl α-nitrooximes by treatment with aluminum(III) oxide has also been reported. 57 Scheme 1 Double nitration of isoxazoles with (het)aryl substituents 42,43,[46][47][48]…”

Section: Condensations Of α-Nitro Ketones or Their Oximesmentioning

confidence: 99%

“…The use of anhydrous solvents is necessary for successful heterocyclization because the O-acyl α-nitrooxime derivatives are sensitive even to traces of water. Usually the reactions are carried out in anhydrous diethylether 52,54,55 or in anhydrous diethylether-THF mixture. 53,56 To achieve almost quantitative yields, the use of triethylamine as a catalyst and molecular sieves are recommended to provide anhydrous conditions.…”

Section: Short Review Syn Thesismentioning

confidence: 99%

“…Et 3 N, MeOH, 0 °C Scheme 5 Condensation of oximes of α-nitro ketones with acyl chlorides [52][53][54][55][56][57] Et 2 O, 25 °C…”

Section: -77%mentioning

confidence: 99%

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Synthetic Approaches to Nitro-Substituted Isoxazoles

et al. 2019

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Nitro-substituted isoxazoles are of utmost interest both as versatile intermediates for targeted organic synthesis and as perspective bioactive compounds for drug development. Nevertheless, the existing approaches to them usually lack generality and strongly depend on the position of the nitro group and on the presence of other substituents in the isoxazole ring. This review provides the first systematization of all available data concerning synthetic approaches to 3-, 4-, and 5-nitroisoxazoles. There are a number of preparative approaches to 4-nitroisoxazoles based on classical heterocyclization reactions of nitro-substituted compounds and the nitration of isoxazoles. 3-Nitro- and, especially, 5-nitroisoxazoles are much less readily available. A few methods affording 3-nitroisoxazoles have been reported, often employing the heterocyclization of unsaturated compounds by treatment with sodium nitrite. The sole general preparative method for 5-nitroisoxazoles, containing a variety of functional groups, employs the heterocyclization of electrophilic alkenes by treatment with tetranitromethane activated with triethylamine.1 Introduction2 Synthesis of 4-Nitroisoxazoles2.1 Nitration of Isoxazoles2.2 Condensations of α-Nitro Ketones or Their Oximes2.3 1,3-Dipolar Cycloaddition of Nitrile Oxides to Acetylenes and Their Synthetic Equivalents2.4 Heterocyclization of Acetylene Derivatives by Treatment with Sodium Nitrite2.5 Heterocyclization of Nitro Derivatives of 1,3-Diketones and Their Synthetic Equivalents2.6 Miscellaneous Methods3 Synthesis of 3-Nitroisoxazoles3.1 Heterocyclization of Acetylene Derivatives or 1,3-Dihalogenoalkenes by Treatment with Sodium Nitrite3.2 Heterocyclization of Morita–Baylis–Hillman Acetates by Treatment with Sodium Nitrite3.3 1,3-Dipolar Cycloadditions4 Synthesis of 5-Nitroisoxazoles4.1 1,3-Dipolar Cycloadditions4.2 Synthesis Using Polynitro Compounds5 Conclusion

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Section: Condensations Of α-Nitro Ketones or Their Oximesmentioning

confidence: 99%

Section: Condensations Of α-Nitro Ketones or Their Oximesmentioning

confidence: 99%

Section: Short Review Syn Thesismentioning

confidence: 99%

“…Et 3 N, MeOH, 0 °C Scheme 5 Condensation of oximes of α-nitro ketones with acyl chlorides [52][53][54][55][56][57] Et 2 O, 25 °C…”

Section: -77%mentioning

confidence: 99%

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Synthetic Approaches to Nitro-Substituted Isoxazoles

et al. 2019

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“…Details of reaction conditions and characterization data related to compounds 2-11 are provided in the Supplementary data [12][13][14][15][16][17][18][19].…”

Section: Synthesesmentioning

confidence: 99%