New fused heterocycles by combined intra-intermolecular criss-cross cycloaddition of nonsymmetrical azines

Man, Stanislav; Kulhánek, Petr; Potáček, Milan; Nečas, Marek

doi:10.1016/s0040-4039(02)01378-3

Cited by 20 publications

(12 citation statements)

References 4 publications

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“…Although compound 7 also bears a stereogenic centre (CH-OH) the signals of the two diastereotopic methyl groups overlap each other. Comparison of the 13 C NMR spectra of compounds 3b-e, 4a and 7 with the results of X-ray analyses enabled us to prove the structure. The carbon atom at the C2-position neighbouring the C 2 F 5 substitution (Scheme 1) showed a triplet with a chemical shift close to 140 ppm and a coupling constant 2 J C,F Ϸ 30 Hz.…”

Section: Resultsmentioning

confidence: 88%

“…[13] We must 3474 Scheme 2. Transformations of azine 1e in reaction with fluorinated enones 2 and 10.…”

Section: Resultsmentioning

confidence: 99%

“…( is an intramolecular attack resulting in the formation of a 1,3-dipole, as predicted by ab initio calculations [16] and proved by the isolation of a bicyclic product, [13] which is a result of a proton transfer in the intermediate, formed in the absence of a dipolarophile, to stabilize the product of the first intramolecular reaction step. Compounds of this structure, pyrrolidino [1,2-b]pyrazoles, are known as biologically active structures.…”

Section: Introductionmentioning

confidence: 87%

“…The third group is a combination of the first and the second approaches: a combined intra-intermolecular cycloaddition. [13][14][15] The first step of this combined cycloaddition are formed by a spontaneous transformation involving fluorine atom migration and hydrogen fluoride elimination. A mechanism of the reaction is discussed to explain the formation of these new heterocycles.…”

Section: Introductionmentioning

confidence: 99%

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Intra–Intermolecular Criss‐cross Cycloaddition of Nonsymmetrical Allenylazines with Fluorinated Enones as an Initial Step in the Synthesis of4H‐Pyrrolo[1,2‐b]pyrazoles

Man¹,

Nečas²,

Bouillon³

et al. 2006

Eur J Org Chem

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Nonsymmetrical allenylazines undergo, in boiling xylene, intramolecular cycloaddition by forming an unstable 1,3‐dipole that reacts with an added dipolarophile. In this paper we report the first intra–intermolecular criss‐cross cycloaddition with a fluorinated enone. Although the expected products with three fused heterocycles were not isolated, new bicyclic products were found and characterized. These compounds are formed by a spontaneous transformation involving fluorine atom migration and hydrogen fluoride elimination. A mechanism of the reaction is discussed to explain the formation of these new heterocycles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Section: Resultsmentioning

confidence: 88%

“…[13] We must 3474 Scheme 2. Transformations of azine 1e in reaction with fluorinated enones 2 and 10.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Intra–Intermolecular Criss‐cross Cycloaddition of Nonsymmetrical Allenylazines with Fluorinated Enones as an Initial Step in the Synthesis of4H‐Pyrrolo[1,2‐b]pyrazoles

Man¹,

Nečas²,

Bouillon³

et al. 2006

Eur J Org Chem

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“…Formation of such structures has already been observed when aromatic homoallenyl azines were heated with low reactive dipolarophiles. 10,11 Compounds 7 prepared in this way are derivatives of isowithasomnine. Products 7 contain an aliphatic chain instead of phenyl in isowithasomnine in position 2.…”

Section: Reactions Of Azinesmentioning

confidence: 99%

Non-symmetrical allenyl azines and their transformations leading to new heterocyclic skeletons

Galeta

Man²,

Potáček³

2009

Arkivoc

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The preparation of new non-symmetrical allenyl azines 5 with aliphatic and alicyclic substituents and their reactions are described. When aldazines 5 were refluxed in xylene formation of bicyclic products 7 was observed. Compounds 7 appeared as derivatives of isowithasomnine. Combined intra-intermolecular criss-cross cycloadditions of azines 5 afforded heterocyclic products 8 and 9 containing three fused five-membered rings. Structures of all new compounds were elucidated by 1 H and 13 C NMR, IR and MS measurements and in some cases by X-ray structure analysis.

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Unexpected Heterocyclic Products from Cycloaddition Reactions of Nonsymmetrical Allenyl Aldoketazines with Substituted Alkynes

Galeta¹,

Man²,

Bouillon³

et al. 2010

Eur J Org Chem

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New fused heterocycles by combined intra-intermolecular criss-cross cycloaddition of nonsymmetrical azines

Cited by 20 publications

References 4 publications

Intra–Intermolecular Criss‐cross Cycloaddition of Nonsymmetrical Allenylazines with Fluorinated Enones as an Initial Step in the Synthesis of4H‐Pyrrolo[1,2‐b]pyrazoles

Intra–Intermolecular Criss‐cross Cycloaddition of Nonsymmetrical Allenylazines with Fluorinated Enones as an Initial Step in the Synthesis of4H‐Pyrrolo[1,2‐b]pyrazoles

Non-symmetrical allenyl azines and their transformations leading to new heterocyclic skeletons

Unexpected Heterocyclic Products from Cycloaddition Reactions of Nonsymmetrical Allenyl Aldoketazines with Substituted Alkynes

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