Synthesis and NMR studies of 2- and 3-fluorosubstitued five-membered heterocycles

Dvornikova, E. V.; Bechcicka, Małgorzata; Kamieńska‐Trela, Krystyna; Krówczyński, Adam

doi:10.1016/j.jfluchem.2003.07.001

Cited by 32 publications

(12 citation statements)

References 44 publications

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“…2-Fluorothiophene also has limited UV activity making detection by TLC and HPLC difficult/inconsistent. Analysis of the radiofluoridation of 2-thienyl(phenyl) iodonium tosylate initially gave a single peak by radio HPLC however after extensive method development (following our concerns, in this case about co-elution) this was found to actually consist of two components}the first fluorobenzene was as expected, the second appeared to be 2-fluorothiophene (an authentic sample was prepared by lithiation of thiophene and a quench with NFSI 6 ). In summary the detection, characterization and isolation of 2-fluorothiophene is extremely problematic.…”

Section: Resultsmentioning

confidence: 88%

Fluoridation of 2‐thienyliodonium salts

Carroll

Jones²,

Tang

2007

Labelled Comp Radiopharmac

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Section: Resultsmentioning

confidence: 88%

Fluoridation of 2‐thienyliodonium salts

Carroll

Jones²,

Tang

2007

Labelled Comp Radiopharmac

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“…Almost all of the experimental 2 J (CC)'s come from the present work; only three, those for compound 30 (Table ), have been taken from Nielsen et al . Among the 188 experimental 1 J (CC)'s, 108 are new and come from the present work; the other are taken from the literature, mostly from our previous work . For some compounds, the data have been re‐measured and marked as such in the tables.…”

Section: Resultsmentioning

confidence: 99%

“…Most of the compounds studied in the present work were either available commercially (Aldrich: 1 , 2 , 3 , 8 , 12 , 13 , 22 , 23 , 24 , 25 , 29 , 32 , 38 , 58 , 59 , 65 , 68 ) or were synthesized according to the published procedures: 4 , 5 , 6 , 7 , 9 , 10 , 11 , 14 , 15 , 16 , 17 , , 18 , 19 , 20 , 21 , 30 , 31 , 33 , 34 , 39 , 40 , 41 , 43 ,, 45 , 46 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 60 , 61 , 62 , 63 , 64 , 66 , 69 , 70 , 72 , and 73 . Some compounds have been obtained as gifts from our colleagues: Dr A. Dąbrowski, 26 , 27 , 28 and Dr A. Kwast, 35 , 36 , 37 .…”

Section: Experimental and Computational Detailsmentioning

confidence: 99%

Substituent effects on indirect carbon–carbon couplings, J(CC), in substituted thiophenes, pyrroles, and furans studied by experiment and theory

Kamieńska‐Trela

Dvornikova

Biedrzycka

2012

J of Physical Organic Chem

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An excellent linear correlation is found between a large set of experimental spin-spin carbon-carbon coupling constants, J(CC), in thiophene, pyrrole, and furan systems and the corresponding B3PW91/6-311++G(2d,p)//B3PW91/ 6-311++G(2d,p) calculated estimates. The correlation does not differ significantly from the simplest relationship possible, J(CC) exp. = J(CC) calcd. , within a small and random spread of about 1 Hz. There are 285 experimental values considered, and 202 out of these are new and come from the present work. The character of the correlation indicates that rovibronic effects on aromatic J(CC)'s, and those of nuclear motions on aromatic J(CC)'s are practically negligible. All of this is in a perfect agreement with our recent extensive studies on aromatic J(CC)'s in pyridine and benzene ring systems. As has been shown by computations, not only large one-bond couplings but also almost all long-range ones occurring between the carbons of the heteroaromatic rings are, with a few exceptions, positive. Significant substituent effects experimentally observed in the one-bond as well as long-range couplings are very accurately reproduced by the computation. The experimental coupling magnitudes vary from ca. 1 to 98 Hz. The J(CC)'s computed for the model variously substituted trimethylsilyl and fluoro derivatives, which are not easily accessible experimentally, span a range of about 130 Hz, from ca. À2 in up to ca. +125 Hz .

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“…This lithiopyrrole will subsequently react readily with a wide variety of electrophiles [398], and may for example also be converted into the 2-alkyl-1-methylpyrroles 261 by treatment with trialkylboranes, followed by addition of iodine or NCS [399,400]. Quenching of 2-lithio-1-methyl-5-noctylpyrrole with N-fluorodibenzenesulfonamide has been used to prepare the labile 2-fluoro-1-methyl-5-n-octylpyrrole [401]. Transmetallation of 260 formed from 1-methylpyrrole and t-BuLi with MgBr 2 or ZnCl 2 gives the corresponding metallated pyrroles 262 and 263, which can subsequently participate in palladium-catalyzed cross-coupling reactions leading to 2-arylpyrroles, or to the 2-pyridylpyrrole 264 [402].…”

Section: C-metallated Pyrrolesmentioning

confidence: 99%