Unprecedented regiochemical control in the formation of aryl[1,2-a]imidazopyridines from alkynyliodonium salts: mechanistic insights.

@article{Dixon2013UnprecedentedRC,
  title={Unprecedented regiochemical control in the formation of aryl[1,2-a]imidazopyridines from alkynyliodonium salts: mechanistic insights.},
  author={Luke I. Dixon and Michael A. Carroll and Thomas J. Gregson and George John Ellames and Ross W. Harrington and William Clegg},
  journal={Organic \& biomolecular chemistry},
  year={2013},
  volume={11 35},
  pages={
          5877-84
        }
}
Aryl(alkynyl)iodonium salts have been demonstrated to be valuable precursors to a diverse range of heteroaromatic ring systems including aryl[1,2-a]imidazopyridines. Successful application, using the recently described aryl(alkynyl)iodonium trifluoroacetate salts, is described, highlighting for the first time that the regioselectivity of this process is both counter-ion and concentration dependent. Studies with a carbon-13 labelled substrate established that the reactions of alkynyliodonium… 
View on PubMed
pubs.rsc.org
23 Citations

Figures and Tables from this paper

23 Citations

Citation Type

Citation Type

Switching of Regioselectivity in a Perfluorohexyl Iodide Mediated Synthesis of Phenylimidazo[1,2‐a]pyridines
TLDR
An array of 3-phenylimidazo[1,2-a]pyridines has been synthesized via perfluorohexyl iodide-mediated coupling of 2-aminopyridine and phenylacetylenes and is complementary to reported methodologies for the synthesis of the 2-phenyl isomer starting from the same substrates.
Regioselective annulation of nitrosopyridine with alkynes: straightforward synthesis of N-oxide-imidazopyridines.
TLDR
A novel method for the regioselective annulation of 2-nitrosopyridines with variably substituted alkynes under mild reaction conditions is developed and shows excellent functional group tolerance and provides easy access to N-oxide-imidazo[1,2-a]pyridine.
Synthesis of Imidazo[1,2-a]pyridines: C-H Functionalization in the Direction of C-S Bond Formation.
TLDR
Recent efforts on the development of new methods for the synthesis of imidazo[1,2-a]pyridines using readily available starting substrates and catalysts under very mild reaction conditions are described.
Regioselective direct C-3 arylation of imidazo[1,2-a]pyridines with aryl tosylates and mesylates promoted by palladium-phosphine complexes.
TLDR
These results represent the first examples of using tosylate- and mesylate-functionalized arenes as the electrophile partners for this regioselective direct arylation of imidazo[1,2-a]pyridine.
Room-temperature transition-metal-free one-pot synthesis of 3-aryl imidazo[1,2-a]pyridines via iodo-hemiaminal intermediate.
TLDR
A mild and efficient one-pot synthesis of 3-aryl imidazo[1,2-a]pyridines in up to 88% yield was developed and the structure was characterized by 2D NMR, IR, and high-resolution mass analysis.
Preparation and Synthetic Utility of Stable 1,3-Enynyl- and 1,3-Dienyl(aryl)iodonium Salts.
TLDR
The facile synthesis of stable enynyl- and dienyl(aryl)iodonium salts is achieved from terminal enynes and these compounds are shown to be useful in a range of transformations.
Metal-free, base catalyzed oxidative amination and denitration reaction: Regioselective synthesis of 3-arylimidazo[1,2-a]pyridines
Metal- and base-free synthesis of imidazo[1,2-a]pyridines through elemental sulfur-initiated oxidative annulation of 2-aminopyridines and aldehydes.
TLDR
The elemental sulfur-promoted oxidative cyclization reaction for the efficient synthesis of substituted imidazo[1,2-a]pyridines has been developed and resulted in excellent yields with the capability of gram-scale synthesis.
Synthesis and Characterization of 2-Phenylimidazo[1,2-a]pyridine: A Privileged Structure for Medicinal Chemistry
A straightforward synthesis of 2-phenylimidazo[1,2-a]pyridine is described. The reaction is designed to demonstrate to students the preparation of a bridged N-heterocycle, in which the heteroatom…
Manganese-Catalyzed Divergent Markovnikov Addition and [2+2+2] Cycloaddition of 2-Carbonyl Indanone with Terminal Alkyne.
TLDR
This method provides an efficient approach for the construction of all-carbon quaternary centers and complex polycyclic hydrocarbon frameworks by the formation of new carbon-carbon single bonds in a regio- and stereoselective manner.
...
1
2
3
...

References

SHOWING 1-10 OF 175 REFERENCES
Regiochemistry of Diels−Alder Reactions of Diverse β-Functionalized Alkynyliodonium Salts with Unsymmetrical Dienes
The reaction of alkynyliodonium salts with unsymmetrically substituted dienes at room temperature in acetonitrile results in iodonium-substituted cyclohexadienes via Diels−Alder cycloaddition. A…
Cu(OTf)2-catalyzed synthesis of imidazo[1,2-a]pyridines from α-diazoketones and 2-aminopyridines
Synthesis and Reactivity of Aryl(alkynyl)iodonium Salts
TLDR
Application of these new reagents to the synthesis of a series of 2-arylfuro[3,2-c]pyridines highlights the potential of this class of materials as precursors to bioactive heterocyclic structures.
Preparation, molecular structure, and diels-alder cycloaddition chemistry of β-functionalized alkynyl(phenyl)iodonium salts
A variety of functionalized alkynyliodonium salts 4a-o are prepared in good yields via a novel iodonium-transfer process between the appropriate alkynylstannanes 2 and PhI + CN. - Otf. The…
Catalytic C-H arylation of SEM-protected azoles with palladium complexes of NHCs and phosphines.
TLDR
These palladium complexes catalyze the efficient C-H arylation of SEM-protected azole heteroarenes and thus provide a good method for preparation of a wide range of arylated free (NH)-azoles including pyrroles, indoles, imidazoles, and imidazo[1,2-a]pyridines.
A new method for the synthesis of cyclopentenones via the tandem Michael addition-carbene insertion reaction of β-ketoethynyl(phenyl)iodonium salts
A variety of substituted 2-cyclopentenones are obtained in good yields (53-82%) via intramolecular 1,5-carbon-hydrogen insertion reactions of [β-(p-toluenesulfonyl)alkylidene]carbenes derived from…
1,3-Dipolar cycloaddition reactions of α-diazocarbonyl compounds, organoazides, and ethynyl(phenyl)iodonium triflate salts
Stereoselective synthesis of (Z)-2-fluoro-1-alkenyl(phenyl)iodonium tetrafluoroborates.
TLDR
(Z)-2-Fluoro-1-alkenyl( phenyl)iodonium salts were stereoselectively prepared by the reaction of alkynyl(phenyl)ium salts with aqueous HF in good yields.
Generation, trapping and fate of alkylidenecarbene-iodonium ylides from the addition of NaN3 to alkynylphenyliodonium tosylates
Direct alkynylation of indole and pyrrole heterocycles.
TLDR
The unique properties of benziodoxolone alkynyl periodinane 1 and gold catalysts have allowed the development of a high yielding, operationally simple reaction for the introduction of silylacetylenes on a large range of indole and pyrrole heterocycles with a wide range of functional groups.
...
1
2
3
4
5
...