From 1,3-cyclohexadiene through nitrosocarbonyl chemistry, the synthesis of pyrimidine isoxazoline-carbocyclic nucleosides

Quadrelli, Paolo; Mella, Mariella; Assanelli, Giulio; Piccanello, Andrea

doi:10.1016/j.tet.2008.05.061

Cited by 13 publications

(8 citation statements)

References 66 publications

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“…Recently, we developed two alternative entries to nitrosocarbonyls through the mild oxidation of nitrile oxides 5 with N -methylmorpholine- N -oxide (NMO) and the clean photolysis and thermolysis of 1,2,4-oxadiazole-4-oxides 6 …”

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confidence: 99%

The Remarkable Cis Effect in the Ene Reactions of Nitrosocarbonyl Intermediates

et al. 2009

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Nitrosocarbonyls are fleeting and highly reactive intermediates that undergo ene reactions in a two-step fashion. The addition steps are rate and product determining and lead to polarized diradicals that readily enter the H-abstraction step yielding the ene products. The addition TSs are reached early, and the stabilizing CH...O contacts drive the reactions to the cis adducts. B3LYP calculations alone do not describe the correct ordering of addition TSs in the ene reaction with trimethylethylene and (E)- and (Z)-3-methyl-2-pentenes. Only at the MPWB1K level of treatment, medium-range noncovalent interactions are successfully recovered, accounting satisfactorily for the experimental selectivities. The more stable and isolable ArNOs exhibit late addition TSs, and distortion energies become dominant driving the reaction exclusively to the Markovnikov adducts.

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confidence: 99%

The Remarkable Cis Effect in the Ene Reactions of Nitrosocarbonyl Intermediates

et al. 2009

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“…Other dienes were used to trap 1i such as 1,3-cyclohexadiene (HDA cycloadduct 37 yield: 81%) ,, allowing preparation of carbocyclic nucleosides and 9,10-DMA whose HDA cycloadduct was isolated in 90% yield …”

Section: Nitrosocarbonyl Generation Methodsmentioning

confidence: 99%

“…271 the same procedure was followed for large-scale preparation of the HDA cycloadduct which served for the synthetic elaboration into several structures, including carbocyclic nucleosides and biomimetic compounds. 274−284 Other dienes were used to trap 1i such as 1,3-cyclohexadiene (HDA cycloadduct 37 yield: 81%) 271,285,286 allowing preparation of carbocyclic nucleosides and 9,10-DMA whose HDA cycloadduct was isolated in 90% yield. 271 The nitrosocarbonyl benzene 1i was extensively used to test the application of the oxidative method from nitrile oxides and NMO in the ene reactions in the presence of a variety of alkenes at different degrees of substitution on the CC double bond (Scheme 143).…”

Section: Chemical Reviewsmentioning

confidence: 99%

Generation and Trapping of Nitrosocarbonyl Intermediates

Memeo

Quadrelli

2017

Chem. Rev.

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The nitrosocarbonyls (R-CONO) are highly reactive species and remarkable intermediates toward different synthetic targets. This review will cover a research area whose impact in current organic synthesis is constantly increasing in the chemical community. This review represents the first and comprehensive picture on the generation and trapping of nitrosocarbonyls and is solidly built on more than 380 papers. Six different classes of key starting materials such as hydroxamic acids, N-hydroxy carbamates, N-hydroxyureas, nitrile oxides, and 1,2,4-oxadiazole-4-oxides were highlighted. The content of the review surveys all the methods to generate the nitrosocarbonyls through different approaches (oxidative, thermal, photochemical, catalytic, aerobic, and the less common ones) in the light of efficiency, yields, and mildness. The most successful trapping agents employed to catch these fleeting intermediates are reviewed, exploiting their superior dienophilic, enophilic, and electrophilic power. The work is completed by paragraphs dedicated to the detection of the intermediates, theoretical studies, and insights about the challenges and future directions for the field.

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“…As reported by Quadrelli and coworkers in 2008, 1,3- DP cycloaddition of in situ-generated nitrile oxide into specially designed dipolarophile was a starting point in the procedure leading to pharmacologically attractive nucleoside analogues— Scheme 48 [ 53 ].…”

Section: Syntheses Of Substituted 2-isoxazolines Via 13-dp Cycloaddit...mentioning

confidence: 99%

Nitrile Oxide, Alkenes, Dipolar Cycloaddition, Isomerization and Metathesis Involved in the Syntheses of 2-Isoxazolines

et al. 2023

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The involvement of 1,3-dipolar cycloaddition (1,3-DP), double bond migration, metathesis, and nitrile oxide (including in situ-generated nitrile oxide) as dipoles, together with the C=C bond containing dipolarophiles, in the syntheses of 2-isoxazolines is presented. Methods for synthesizing isoxazolines (other than 1,3-DP cycloaddition) were also presented briefly. Various methods of nitrile oxide preparation, especially in situ-generated procedures, are presented. Special attention was paid to the application of various combinations of 1,3-DP cycloaddition with double bond migration (DBM) and with alkene metathesis (AM) in the syntheses of trisubstituted isoxazolines. Allyl compounds of the type QCH2CH=CH2 (Q = ArO, ArS, Ar, and others) play the role of dipolarophile precursors in the combinations of DPC mentioned, DBM and AM. Mechanistic aspects of cycloadditions, i.e., concerted or stepwise reaction mechanism and their regio- and stereoselectivity are also discussed from experimental and theoretical points of view. Side reactions accompanying cycloaddition, especially nitrile oxide dimerization, are considered. 2-Isoxazoline applications in organic synthesis and their biological activity, broad utility in medicine, agriculture, and other fields were also raised. Some remaining challenges in the field of 1,3-DP cycloaddition in the syntheses of isoxazolines are finally discussed.

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From 1,3-cyclohexadiene through nitrosocarbonyl chemistry, the synthesis of pyrimidine isoxazoline-carbocyclic nucleosides

Cited by 13 publications

References 66 publications

The Remarkable Cis Effect in the Ene Reactions of Nitrosocarbonyl Intermediates

The Remarkable Cis Effect in the Ene Reactions of Nitrosocarbonyl Intermediates

Generation and Trapping of Nitrosocarbonyl Intermediates

Nitrile Oxide, Alkenes, Dipolar Cycloaddition, Isomerization and Metathesis Involved in the Syntheses of 2-Isoxazolines

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