Migration aptitudes of unsaturated groups in thermal [1,5]-sigmatropic rearrangements

Schiess, Peter; Fünfschilling, Peter C.

doi:10.1016/s0040-4039(01)85206-0

Cited by 18 publications

(3 citation statements)

References 11 publications

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“…Both of these carbanions can undergon ucleophilic addition to the carbonyl carbon atoms to form the ring intermediates, which finally lead to either o-( 2;S cheme 3) or p-tolualdehyde (3;S cheme 3) through aromatization. [44] Thus,t he selectivity towards o-o rptolualdehyde is determined by the stabilityo ft he corresponding carbanion formed from the hydrogen abstraction of 5methyl-dihept-2-enal at either the a or g positions.…”

Section: Synthesis Of C 8 Compoundsmentioning

confidence: 99%

Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

et al. 2016

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A new type of catalyst has been designed to adjust the basicity and level of molecular confinement of KNaX faujasites by controlled incorporation of Mg through ion exchange and precipitation of extraframework MgO clusters at varying loadings. The catalytic performance of these catalysts was compared in the conversion of C2 and C4 aldehydes to value-added products. The product distribution depends on both the level of acetaldehyde conversion and the fraction of magnesium as extraframework species. These species form rather uniform and highly dispersed nanostructures that resemble nanopetals. Specifically, the sample containing Mg only in the form of exchangeable Mg(2+) ions has much lower activity than those in which a significant fraction of Mg exists as extraframework MgO. Both the (C6+C8)/C4 and C8/C6 ratios increase with additional extraframework Mg at high acetaldehyde conversion levels. These differences in product distribution can be attributed to 1) higher basicity density on the samples with extraframework species, and 2) enhanced confinement inside the zeolite cages in the presence of these species. Additionally, the formation of linear or aromatic C8 aldehyde compounds depends on the position on the crotonaldehyde molecule from which abstraction of a proton occurs. In addition, catalysts with different confinement effects result in different C8 products.

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Section: Synthesis Of C 8 Compoundsmentioning

confidence: 99%

Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

et al. 2016

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“…( +)-l-E-EthoxycarbonyZvinyZ-l,3-dimethyZindene.- 3 340 cm-1; ~( 6 0 MHz) 2.79 (4 H, m, aromatic), 4.02 (1 H, q, J 1.5 Hz), 4.34 (2 H , m, olefinic), 6.03 (2 H, broadened inner lines of AB-system), 7.78 (1 H , br s, OH), 7.93 (3 H, d , J 1.5 Hz), and 8.66 (3 H, s ) ; [a]D24 +94.8" (c 1.10, CHCl,) .…”

Section: Resultsmentioning

confidence: 99%

o-Quinonoid compounds. Part 16. 1,5-Shift of vinyl groups in 1,3-dimethylindenes; product studies and migratory aptitudes of substituted vinyl groups

Field¹,

Jones²

1980

J. Chem. Soc., Perkin Trans. 1

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“…The key step in the formation of pyrazole 3 is the facile sigmatropic rearrangement of the phosphoryl group. Although acyl groups are well known for their high migratory aptitude, for example a formyl group migrates over 100 times faster than hydrogen in [1,5]‐sigmatropic rearrangements in cyclohexa‐2,4‐dienes, [42] and a carboxylate migrates extremely readily in 3 H ‐pyrazoles, [43] almost nothing is known about the participation of P=O containing groups in sigmatropic rearrangements. Nevertheless it is clear from Regitz [37] .…”

Section: Figurementioning

confidence: 99%

Diazophosphonates: Effective Surrogates for Diazoalkanes in Pyrazole Synthesis

Ruffell

Smith

Green

et al. 2021

Chemistry A European J

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Diazophosphonates, readily prepared from α‐ketophosphonates by oxidation of the corresponding hydrazones in batch or in flow, are useful partners in 1,3‐dipolar cycloaddition reactions to alkynes to give N‐H pyrazoles, including the first intramolecular examples of such a process. The phosphoryl group imbues a number of desirable properties into the diazo 1,3‐dipole. The electron‐withdrawing nature of the phosphoryl stabilizes the diazo compound making it easier to handle, whilst the ability of the phosphoryl group to migrate readily in a [1,5]‐sigmatropic rearrangement enables its transfer from C to N to aromatize the initial cycloadduct, and hence its facile removal from the final pyrazole product. Overall, the diazophosphonate acts as a surrogate for the much less stable diazoalkane in cycloadditions, with the phosphoryl group playing a vital, but traceless, role. The cycloaddition proceeds more readily with alkynes bearing electron‐withdrawing groups, and is regiospecific with asymmetrical alkynes. The potential of diazophosphonates for use in bioorthogonal cycloadditions is demonstrated by their facile addition to strained alkynes.

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Migration aptitudes of unsaturated groups in thermal [1,5]-sigmatropic rearrangements

Cited by 18 publications

References 11 publications

Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

o-Quinonoid compounds. Part 16. 1,5-Shift of vinyl groups in 1,3-dimethylindenes; product studies and migratory aptitudes of substituted vinyl groups

Diazophosphonates: Effective Surrogates for Diazoalkanes in Pyrazole Synthesis

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Migration aptitudes of unsaturated groups in thermal [1,5]-sigmatropic rearrangements

Cited by 18 publications

References 11 publications

Synthesis of C4 and C8 Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

Synthesis of C4 and C8 Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

o-Quinonoid compounds. Part 16. 1,5-Shift of vinyl groups in 1,3-dimethylindenes; product studies and migratory aptitudes of substituted vinyl groups

Diazophosphonates: Effective Surrogates for Diazoalkanes in Pyrazole Synthesis

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Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity