Selective transannular cyclization of 3,7-bismethylenebicyclo[3.3.1]nonane with F-TEDA-BF4 in protic solvents

Serguchev, Yurii A.; Lourie, Lyudmila F.; Ponomarenko, Maxim V.

doi:10.1070/mc2000v010n03abeh001278

Cited by 8 publications

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“…3 Side difluorination occurred in the transannular cyclization of 3,7-bismethylenebicyclo[3.3.1]nonane with F-TEDA-BF 4 in protic solvents, where 1-fluoro-3-fluoromethyladamantane was detected as an impurity among the major products, 1-RO-3fluoromethyladamantanes (R = H, Alk or Ac). 4 Here, we report the unusual and intriguing finding: under certain conditions, F-TEDA-BF 4 can act as an effective difluorinating agent in the transannular cyclization of 3,7-bismethylenebicyclo [3.3.1]nonane and its derivatives with a methyl or phenyl substituent at one of the exocyclic methylene groups.…”

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confidence: 88%

“…2 The side formation of difluorides was observed in the reactions of F-TEDA-BF 4 with unsaturated substrates. 3,4 For example, 1,2-difluorosaccharides were reported to form as by-products, in addition to monofluorinated carbohydrates, in the fluorination of glycals with F-TEDA-BF 4 in nitromethane in the presence of alcohols. 3 Side difluorination occurred in the transannular cyclization of 3,7-bismethylenebicyclo[3.3.1]nonane with F-TEDA-BF 4 in protic solvents, where 1-fluoro-3-fluoromethyladamantane was detected as an impurity among the major products, 1-RO-3fluoromethyladamantanes (R = H, Alk or Ac).…”

mentioning

confidence: 99%

“…The starting substrates (3,7-bismethylenebicyclo[3.3.1]nonane 1a, 3-ethylidene-7-methylenebicyclo[3.3.1]nonane 1b and 3-benzylidene-7-methylenebicyclo[3.3.1]nonane 1c) were prepared by the published procedures. 4,5 When the reaction was carried out in monoglyme, difluoro-substituted adamantanes 2a-c were obtained in high yields. † It was of interest to elucidate whether monoglyme is a specific solvent promoting the difluorination.…”

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confidence: 99%

“…The 1 H, 13 C and 19 F NMR spectra of products 4 and 5 are in agreement with published data. 4 Refluxing the reaction mixture with 3 ml of aqueous 60% HBr for 2 h afforded 1-bromo-3-fluoromethyladamantane 6 in 54% isolated yield. By passing an HCl gas through the reaction mixture over 7 h at 80 ºC, 1-chloro-3-fluoromethyladamantane 7 was obtained in 50% isolated yield.…”

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confidence: 99%

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Difluorination ability of F-TEDA-BF4 in the transannular cyclization of bicyclo[3.3.1]nonane dienes in monoglyme

Serguchev

Lourie

Ponomarenko

2002

Mendeleev Communications

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Difluorination ability of F-TEDA-BF4 in the transannular cyclization of bicyclo[3.3.1]nonane dienes in monoglyme

Serguchev

Lourie

Ponomarenko

2002

Mendeleev Communications

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“…When 4methylene6 phenylhexanoic acid was treated in acetonitrile with 25 and NaHCO 3 , the desired product 26 was obtained in only 12% yield. The protocy clized product 27 was isolated in 44% yield along with 7% yield of the fluorinated lactam 28, a product resulting from the participation of the [28]. They hypothesized that, since bicyclononane systems could undergo cyclization in the presence of elec trophiles such as iodine or bromine, the system may cyclize with the addition of an electrophilic source of fluorine, such as Selectfluor (FiguRe 20).…”

Section: Fluorocyclizations Featuring An Electrophilic Fluorinationmentioning

confidence: 98%

Developments in Fluorocyclization Methodologies

2009

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Fluorinated organic compounds constitute a significant proportion of medicines marketed today. Since heterocycles are submotifs frequently encountered in lead compounds, the corresponding fluorinated molecules that possess coupling functional groups to increase structural complexity are sought-after building blocks, especially those with stereogenic elements. To access fluoro-heterocycles, fluorocyclizations constitute an important category of reactions that permit multiple bond construction in one pot. Reactions featuring both nucleophilic and electrophilic sources of fluorine have proved valuable for the delivery of fluorinated carbo- and heterocycles. Mechanistically, two scenarios have been validated with the fluorination occurring either prior to or after the cyclization event. Fluorinated biologically active molecules prepared by employing a fluorocyclization protocol are rare, with two notable exceptions being the synthesis of fluorogypsetin and fluorobrevianamide E. Various levels of diastereocontrol were obtained with best results observed when the cyclization step precedes the fluorination. To date, asymmetric fluorocyclizations have not been explored, with the exception of a Nazarov fluorination process. In essence, this process features a catalytic asymmetric cyclization followed by a diastereoselective fluorination. Asymmetric fluoroheterocyclizations are, however, not known. For this methodology to serve medicinal chemistry, conceptual advances are essential to access fluorinated pharmacophores with programmable stereocontrol as and when necessary.

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Electrophilic Fluorination withN–FReagents

Baudoux

Cahard

2008

Organic Reactions

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The synthesis of selectively fluorinated molecules is an important challenge in organic chemistry. This topic has received considerable attention because of the utility of fluorinated compounds in a wide variety of disciplines. There are three types of fluorination depending on whether the fluorine atom is radical, anionic, or cationic. Fluorine radicals are of little synthetic use because of the difficulties in controlling their reactivity. Fluorine is utilized in nucleophilic as well as electrophilic fluorinations Molecular fluorine is the simplest reagent of this type, however, its safe handling is difficult. Stable, selective reagents are crucial to the development of electrophilic fluorination. N‐F reagents have emerged as generally safer and easier to handle selective sources of electrophilic fluorine. N‐F reagents offer a range of fluorinating powers and some are available commercially. Two classes are known: neutral N‐F reagents and quaternary ammonium N‐F reagents (quaternary salts are usually the more powerful). N‐F reagents popularity arises because they posses a long shelf life, several are commercially available, and they can be handled safely in glassware. The drawback is the preferential use of molecular fluorine for their preparation. This article deals with the preparation and the use of all types of electrophilic fluorinating agents possessing the N‐F moiety.

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Selective transannular cyclization of 3,7-bismethylenebicyclo[3.3.1]nonane with F-TEDA-BF4 in protic solvents

Cited by 8 publications

References 7 publications

Difluorination ability of F-TEDA-BF4 in the transannular cyclization of bicyclo[3.3.1]nonane dienes in monoglyme

Difluorination ability of F-TEDA-BF4 in the transannular cyclization of bicyclo[3.3.1]nonane dienes in monoglyme

Developments in Fluorocyclization Methodologies

Electrophilic Fluorination withN–FReagents

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