A Novel Dimerization Mode of a Cyclic Ketene Imine

Langhals, Elke; Huisgen, Rolf; Polborn, Kurt

doi:10.1002/chem.200400264

Cited by 5 publications

(2 citation statements)

References 23 publications

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“…Recently we observed an even smaller angle for an olefinic F-C-F (108.2°) in a dimer of ketene imine 8B. [33] This F-C-F angle contraction in fluorinated alkenes aroused considerable interest in the past (see review in ref. [34] ).…”

Section: (2+3) Cycloadditions Of Ketene Imines 8 With Diazomethanementioning

confidence: 98%

Cycloadditions with Cyclic Seven‐Membered Ketene Imines

2005

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The cyclic seven-membered ketene imines 8 -isolable despite ring strain -are available by reactions of thiocarbonyl ylides 3 with 2,3-bis(trifluoromethyl)fumaronitrile (4). In contrast to open-chain ketene imines, 8A-8C underwent (2+2) cycloadditions with ethyl vinyl ether at the C=N double bond; the diastereomeric cycloadducts 10 and 11 were characterized by their spectra, and 10A by X-ray analysis. The corresponding adduct 12 from 8A and 2-methoxypropene easily hydrolyzed to give 14. When 8A-8C were treated with diazomethane, (2+3) cycloadditions took place side by side

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Section: (2+3) Cycloadditions Of Ketene Imines 8 With Diazomethanementioning

confidence: 98%

Cycloadditions with Cyclic Seven‐Membered Ketene Imines

2005

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“…A surprising dimerization of the ketenimine 48b occurred in acetonitrile at room temperature in the presence of KF as a catalyst. The formation of two diastereoisomers of product 104 in a ratio of 1:1 was explained by the fluoride ion-initiated reaction mechanism via intermediate 105 ( Scheme 36 ) [ 78 ].…”

Section: Seven-membered Sulfur-containing Heterocyclesmentioning

confidence: 99%

Synthesis of Fluorinated and Fluoroalkylated Heterocycles Containing at Least One Sulfur Atom via Cycloaddition Reactions

2022

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Fluorinated heterocycles constitute an important group of organic compounds with a rapidly growing number of applications in such areas as medicinal chemistry, agrochemicals production, polymer chemistry, as well as chemistry of advanced materials. In the latter case, fluorinated thiophenes are considered as a lead class of compounds with numerous spectacular applications. On the other hand, cycloaddition reactions offer a superior methodology for stereo-chemically controlled synthesis of heterocycles with a diverse ring size and a variable number of heteroatoms. A comprehensive review of methods based on cycloaddition reactions and applied for construction of fluorinated and/or fluoroalkylated S-heterocycles has not yet been published. For this reason, the main goal of the presented review was to fill the existing gap and to summarize the results published over last six decades. In this context, the [3+2]- and [4+2]-cycloadditions (Huisgen reactions, and Diels–Alder reactions, respectively) are of special importance. Some questions related to the discussed mechanisms of cycloaddition processes observed in reactions with electron deficient, fluorinated substrates (dipolarophiles and dienophiles), and electron-rich sulfur containing counter partners, are of fundamental importance for the development of interpretations of organic reaction mechanisms.

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