Metalated heterocycles in organic synthesis: Recent applications

Chinchílla, Rafael; Nájera, Carmén; Yus, Miguel

doi:10.3998/ark.5550190.0008.a13

Cited by 34 publications

(4 citation statements)

References 157 publications

(166 reference statements)

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“…The next section will focus on the metalation of N -activated pyridine species followed by the reaction with electrophiles, particularly the α-lithiation of pyridine N -oxides and pyridine Lewis acid complexes. Pyridines are significantly more acidic than the analogous benzenes, and the direct metalation of pyridines has been widely studied and reviewed elsewhere. − Important advances have been made in this area; however, close acidities of the pyridine C–H groups make regioselectivity an issue . Dimerization to the bipyridine, addition of the base to the ring, or the preferential deprotonation of side chains also constitute potential limitations of the strategy.…”

Section: Electrophilic Additions To N-heteroatom Pyridinium Species B...mentioning

confidence: 99%

Synthesis of Pyridine and Dihydropyridine Derivatives by Regio- and Stereoselective Addition toN-Activated Pyridines

et al. 2012

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Introduction 2643 2. Nucleophilic Addition of Organometallic Reagents to N-Acyl Pyridinium Salts 2644 2.1. Regioselective Additions to N-Acyl Pyridinium Species and Their Derivatives 2644 2.1.1. Influence of Pyridine Ring Substituents on Regioselectivity of Addition 2646 2.1.2. Control of Regio-and Diastereoselectivity by the Introduction of Removable Blocking Groups 2648 2.2. Synthesis of 4-Pyridones: 1,2-Addition to 4-Methoxypyridines 2649 2.2.1. Diastereoselective Addition to 3-Trialkylsilyl-4-methoxypyridines 2651 2.2.2. Application in the Synthesis of Natural Products Containing Chiral Piperidine Units 2652 2.3. Diastereoselective 1,2-Addition to N-Imidoyl Pyridinium Salts 2652 2.4. Enantioselective 1,2-Addition Controlled by a Chiral Catalyst 2657 2.5. Diastereoselective 1,4-Addition Controlled by Pyridine 3-Substituents 2657 3. Nucleophilic Addition to N-Alkyl Pyridinium Salts and Their Derivatives 2659 3.1. Regioselective Additions to N-Alkyl Pyridinium SaltsNature of the Nucleophile 2659 3.1.1. Organometallic Reagents as Nucleophiles 2659 3.1.2. Cyanide as Nucleophile 2663 3.2. Diastereoselective Additions of Organometallic Reagents to N-Alkyl Pyridinium Salts 2663 3.3. Regioselective Additions of Enolates to N-Alkyl Pyridinium Salts 2666 3.3.1. Wenkert Procedure: Seminal Work 2667 3.3.2. Wenkert Procedure: Addition of Nucleophiles Positioned at the Nitrogen of Indole Derivatives 2670 3.3.3. Wenkert Procedure: Addition of Enolates Located at the C-2/C-3 Position of Indoles 2671 3.3.4. Addition of Miscellaneous Nucleophiles to N-Alkyl Pyridinium Species 2674 4. Nucleophilic Additions to N-Heteroatom Pyridinium Species 2676 4.1. Nucleophilic Additions to Pyridine N-Oxides and N−O Salts 4.1.1. Properties, Synthesis, and Deprotection of Pyridine N-Oxides 4.1.2. Addition of Grignard Reagents to Pyridine N-Oxides 4.1.3. Addition of Cyanide Nucleophiles via Reissert-Type Reactions 4.1.4. Addition of Hetero Nucleophiles to Pyridine N-Oxides and N−O Salts 4.

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Section: Electrophilic Additions To N-heteroatom Pyridinium Species B...mentioning

confidence: 99%

Synthesis of Pyridine and Dihydropyridine Derivatives by Regio- and Stereoselective Addition toN-Activated Pyridines

et al. 2012

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“…A similar behavior is observed in the 1 H DOSY spectra of 3 (D = 9.3 × 10 −10 m 2 /s) and 4 (D = 6.3 × 10 −10 m 2 /s). In contrast, in the solution of [(THF) 2 Li-(C 4 H 3 S)] 2 (2), the observed diffusion coefficient of THF (1.7 × 10 −9 m 2 /s) varies significantly from that of the metalated thiophene (9.3 × 10 −10 m 2 /s), but is still substantially lower than that of noncoordinating small molecules such as toluene (2.6 × 10 −9 m 2 /s) (see Figure 5, left). This indicates that, in solution, THF molecules partially dissociate from the lithiated thiophene structure, possibly leaving Li atoms 3-fold-coordinated.…”

Section: ■ Resultsmentioning

confidence: 99%

“…In organic syntheses both positions next to the sulfur atom are readily accessible to derivatization, 1 normally starting from a mono-or dihalogenated or -metalated species. 2 Most recently a hetero-s-block-metalated thienyl complex, [(TMEDA) 2 Na,Mg(C 4 H 3 S) 3 ] (TMEDA = N,N,N′,N′-tetramethylethylene-1,2-diamine), was published. 3 Transition-metal thienyl complexes are equally appealing and have been synthesized in past decades in vast variety.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Thiophene, the sulfur-containing five-membered aromatic heterocycle, is one of the most versatile scaffolds in various chemical areas, spanning the wide range from organic synthesis via organometallic chemistry and materials science to life science. In organic syntheses both positions next to the sulfur atom are readily accessible to derivatization, normally starting from a mono- or dihalogenated or -metalated species . Most recently a hetero-s-block-metalated thienyl complex, [(TMEDA) 2 Na,Mg(C 4 H 3 S) 3 ] (TMEDA = N , N , N ′, N ′-tetramethylethylene-1,2-diamine), was published .…”

Section: Introductionmentioning

confidence: 99%

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Aggregation of Donor Base Stabilized 2-Thienyllithium in a Single Crystal and in Solution: Distances from X-ray Diffraction and the Nuclear Overhauser Effect

et al. 2011

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Various 2-thienyllithium derivatives were investigated in the solid state by X-ray diffraction and in solution by 2D NMR experiments. The determined structures of [(Et(2)O)Li(C(4)H(3)S)](4) (1), [(THF)(2)Li(C(4)H(3)S)](2) (2), [(DME)Li(C(4)H(3)S)](2) (3), [(TMEDA)Li(C(4)H(3)S)](2) (4), and [(PMDETA)Li(C(4)H(3)S)] (5) (DME = 1,2-dimethoxyethane, TMEDA = N,N,N',N'-tetramethylethylene-1,2-diamine, and PMDETA = N,N,N',N",N"-pentamethyldiethylenetriamine) were solved in nondonating toluene and provide firm ground for diffusion-ordered NMR spectroscopy as well as heteronuclear Overhauser enhancement NMR spectroscopy. The distance relation of nuclear Overhauser effects with a factor of r(-6) is employed to gain further insight into the aggregation degree of 1-5 in solution. Comparison of the slope provided by the linear region of the buildup curves and of the ∑r(-6) calculated distances from the crystal structures offers a handle to judge the structure retention versus conversion in solution. The structures of 3-5 are maintained in toluene solution. The data of 2, however, indicate a partial dissociation or a rapid exchange between the vertices of a tetrameric core and free THF molecules. Auxiliary exchange spectroscopy investigations showed that the signals of the nitrogen donor base containing compounds 4 and 5 exchange with the signals of nonlithiated thiophene. This is explained by exchange of the deuterium by a hydrogen atom via lithiation of toluene molecules.

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Organic Diselenides, Ditellurides, Polyselenides and Polytellurides. Synthesis and Reactions

Потапов¹

2013

Patai's Chemistry of Functional Groups

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Organic diselenides and ditellurides represent very important classes of compounds, which find valuable applications in organochalcogen chemistry and in organic synthesis. The review describes the main efficient and reliable approaches to organic diselenides and ditellurides and their principal chemical reactions. Examples of syntheses of tri‐ and polyselenides and ‐tellurides have been presented. Typical reactions of organic diselenides and ditellurides with nucleophiles, electrophiles, radicals, carbenes and compounds containing the element‐element bond have been discussed in the review. Regio‐ and stereoselective reactions of organic diselenides and ditellurides with unsaturated compounds provide various chalcogenyl and bis(chalcogenyl) derivatives, which are often used in further transformations including stereoselective synthesis of functionalized alkenes. Along with valuable chemical reactions, organic diselenides and ditellurides act as precursors of both nucleophilic and electrophilic selenium and tellurium species, which participate in various useful transformations. The remarkable property of reacting with high regio‐ and stereoselectivity finds widespread application of selenium and tellurium species in organic synthesis. Besides valuable synthetic applications, organic diselenides and ditellurides exhibit various biological activities including glutathione peroxidase‐like action. Aspects of biological activity of these compounds as well as a comparison of selenol–diselenide and thiol–disulfide reversible exchange reactions have been discussed in the review.

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Metalated heterocycles in organic synthesis: Recent applications

Cited by 34 publications

References 157 publications

Synthesis of Pyridine and Dihydropyridine Derivatives by Regio- and Stereoselective Addition toN-Activated Pyridines

Synthesis of Pyridine and Dihydropyridine Derivatives by Regio- and Stereoselective Addition toN-Activated Pyridines

Aggregation of Donor Base Stabilized 2-Thienyllithium in a Single Crystal and in Solution: Distances from X-ray Diffraction and the Nuclear Overhauser Effect

Organic Diselenides, Ditellurides, Polyselenides and Polytellurides. Synthesis and Reactions

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