New cycloaddition reactions of perfluoro-1,3,4-oxadiazoles

Vasil'ev, N. V.; Romanov, D. V.; Truskanova, T. D.; Zatonsky, George V.

doi:10.1070/mc2006v016n03abeh002320

Cited by 7 publications

(3 citation statements)

References 2 publications

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“…In this case, we failed to isolate a double cycloaddition product. At the same time, an intramolecular cycloaddition product (11), as well as trifluoroacetamide (12) and 2-trifluoromethyl-4,5-dimethylpyridine (13), which unexpectedly resulted from this interaction, were isolated (Scheme 6). The formation of compounds 12 and 13 can be explained by an relative reactivity of 2,3-dimethylbutadiene, which is able to undergo [4 + 2]-cycloaddition to the C N bond of oxadiazole 1a forming an unstable cycloadduct (12a).…”

Section: Resultsmentioning

confidence: 94%

“…Interactions of oxadiazole 1a with divinyl ether, divinyl sulfide, and diallyl ether. 23 was separated by repeated vacuum fractionation, and its structure was confirmed by NMR spectroscopy and single crystal X-ray diffraction analysis [13]. It should be also pointed out, that oxadiazole 1c did not react with cycloheptatriene under analogous conditions.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Intramolecular cycloaddition of fluorinated 1,3,4-oxadiazoles to dienes

Vasil'ev

Romanov²,

Bazhenov³

et al. 2007

Journal of Fluorine Chemistry

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Intramolecular cycloaddition of fluorinated 1,3,4-oxadiazoles to dienes

Vasil'ev

Romanov²,

Bazhenov³

et al. 2007

Journal of Fluorine Chemistry

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“…Originally inspired by the potential development of sequential intramolecular inverse electron demand Diels–Alder reactions of unsymmetrically substituted 1,2,4,5-tetrazines, − our approach ultimately enlisted an alternative cascade cycloaddition reaction of electron-deficient five-membered heterocyclic azadienes using 1,3,4-oxadiazoles in the initiating inverse electron demand Diels–Alder reaction. , Although a limited number of reports had described the cycloadditions of electron-deficient 1,3,4-oxadiazoles, they typically employed symmetrical oxadiazoles bearing two strong electron-withdrawing substituents (CF 3 , SO 2 Et, CO 2 Me) and all had been examined only in intermolecular reactions (Figure ). − Reactions of olefinic dienophiles were found to proceed through an initial [4 + 2] cycloadduct that loses N 2 to provide a carbonyl ylide that subsequently reacted again with the same olefin in a 1,3-dipolar cycloaddition reaction to provide only 2:1 cycloadducts, limiting their synthetic utility.…”

Section: Introductionmentioning

confidence: 99%

Tandem Intramolecular Diels–Alder/1,3-Dipolar Cycloaddition Cascade of 1,3,4-Oxadiazoles: Initial Scope and Applications

Sears

Boger

2016

Acc. Chem. Res.

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Conspectus A summary of the development and initial studies on the scope of a powerful tandem intramolecular [4 + 2]/[3 + 2] cycloaddition cascade of 1,3,4-oxadiazoles is detailed and provides the foundation for its subsequent use in organic synthesis. Implemented with substrates in which both the initiating dienophile and subsequent dipolarophile are tethered to the 1,3,4-oxadiazoles, the studies expanded the scope of oxadiazoles that participate in the reaction cascade, permitted the use of differentiated dienophiles and dipolarophiles, extended their use to unsymmetrical dienophiles and dipolarophiles, provided exclusive control of the cycloaddition regioselectivities, and imposed exquisite control on the cycloaddition stereochemistry. As key reactivity and stereochemical features of the reactions were being defined, the cascade cycloaddition reaction was implemented in the total synthesis of a series of alkaloids including (−)-vindoline, (−)-vindorosine, the closely related natural products (+)-4-desacetoxyvindoline and (+)-4-desacetoxyvindorosine, natural minovine, (+)-N-methylaspidospermidine, (+)-spegazzinine, (−)-aspidospermine, and a number of key analogues. Most recently it was used in the divergent total syntheses of (+)-fendleridine, (−)-kopsinine, (−)-kopsifoline D, and (−)-deoxoapodine, in which four different strategic bonds in four different classes of the hexacyclic alkaloids were formed from a common cascade cycloaddition intermediate. A large number of vindoline analogues were prepared by variations on the cascade cycloaddition reaction for single step incorporation into analogues of vinblastine. These structural changes to vindoline permitted both systematic alterations to the peripheral substituents as well as deep-seated changes to the core structure and embedded functionality of vinblastine not previously accessible. Although explored initially for accessing vindoline and vinblastine, the use of the cycloaddition cascade in the total synthesis of an impressive range of additional natural products illustrate the power of the methodology. Alternative tethering strategies for the cascade cycloaddition reaction, combined intramolecular and intermolecular variants of either the initiating Diels–Alder reaction or the subsequent carbonyl ylide 1,3-dipolar cycloaddition, an expanded examination of the tethered dipolarophile scope, and applications to additional natural product classes represent attractive areas for future work.

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Tandem [4+2]/[3+2] Cycloadditions

Baiazitov¹,

Denmark²

2014

Methods and Applications of Cycloaddition Reactions in Organic Syntheses

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New cycloaddition reactions of perfluoro-1,3,4-oxadiazoles

Cited by 7 publications

References 2 publications

Intramolecular cycloaddition of fluorinated 1,3,4-oxadiazoles to dienes

Intramolecular cycloaddition of fluorinated 1,3,4-oxadiazoles to dienes

Tandem Intramolecular Diels–Alder/1,3-Dipolar Cycloaddition Cascade of 1,3,4-Oxadiazoles: Initial Scope and Applications

Tandem [4+2]/[3+2] Cycloadditions

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