Nucleophilic Selenium

Iwaoka, Michio

doi:10.1002/9783527641949.ch2

Cited by 13 publications

(11 citation statements)

References 262 publications

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“…As a result, intense interest has been directed toward the development of new methods for the synthesis of organoselenium compounds, and a variety of well-established classical methods to introduce a selenium moiety in organic substrates are now available in the literature . One of the ways to access organoselenium compounds is the transformation of elemental selenium into nucleophilic species by reaction with lithium and Grignard reagents or by reduction of diorganyl diselenides by alkali metals or alkali hydrides . Other common approach to introduce a selenium moiety into organic molecules involves the use of selenium electrophilic species, which can be easily prepared by reaction of diorganyl diselenides with a halogen source, although nowadays they are commercially available.…”

Section: Introductionmentioning

confidence: 99%

Sequential Carbon–Carbon/Carbon–Selenium Bond Formation Mediated by Iron(III) Chloride and Diorganyl Diselenides: Synthesis and Reactivity of 2-Organoselenyl-Naphthalenes

2017

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In this paper, we report an intramolecular cyclization of benzylic-substituted propargyl alcohols promoted by iron(III) chloride and diorganyl diselenides to give 2-organoselenyl-naphthalenes via a sequential carbon-carbon/carbon-selenium bond formation. The present reaction tolerated a wide range of substituents in both propargyl alcohols and diorganyl diselenides to give the desired 2-organoselenyl-naphthalenes in good yields with high selectivity. In addition, O-acyl protected propargyl alcohol and propargyl bromide were also subjected to this protocol giving the corresponding 2-organoselenyl-naphthalenes. We found that dichalcogenide species affected the formation of cyclized products, whereas diorganyl diselenides gave high yields, moderate yields were obtained with diorganyl disulfides, and no product formation was found with diorganyl ditellurides. The key transformations could be attributed to the carbon-carbon triple bond activation of benzylic-substituted propargyl alcohols by a seleniranium ion, antiattack of the electron cloud from the aromatic ring at the activated triple bond, and cyclization via an exclusive 6-endo-dig process. We also found that the corresponding 2-organoselenyl-naphthalenes are suitable substrates to the selenium-lithium exchange reactions followed by trapping with aldehydes affording the corresponding secondary alcohols.

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Section: Introductionmentioning

confidence: 99%

Sequential Carbon–Carbon/Carbon–Selenium Bond Formation Mediated by Iron(III) Chloride and Diorganyl Diselenides: Synthesis and Reactivity of 2-Organoselenyl-Naphthalenes

2017

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“…Reactions with selenium give valuable insight into the electronics and redox behavior of a given molecular system because of its ability to exist in a variety of oxidation states. − In addition, selenides and diselenides are useful synthetic targets and play a vital role in the development of organic oxidations , and functionalized alkenes. − ,,− Owing to the poor solubility of elemental selenium in common organic solvents, most reactions involve the use of organochalogenide starting materials (e.g., Ph 2 Se 2 ). One key account involving the N-heterocyclic gallyl (NHGa) anion activating the Se–Se bond of diphenyl diselenide was reported by Jones et al, who isolated a [NHGa(SePh) 2 ] anion (Figure a) .…”

Section: Introductionmentioning

confidence: 99%

Reactions of 9-Carbene-9-Borafluorene Monoanion and Selenium: Synthesis of Boryl-Substituted Selenides and Diselenides

et al. 2021

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Reactions of 9-carbene-9-borafluorene monoanion (1) with elemental selenium and selenium-containing reagents are reported. When compound 1 is reacted with grey selenium in THF, various boryl-substituted selenides and diselenides are produced (2−6), including molecules resulting from migration of the carbene ligand Dipp group (Dipp = 2,6-diisopropylphenyl). However, when a similar reaction between 1 and grey selenium is performed in toluene in the presence of 18-crown-6, boryl-substituted selenide 7 is obtained as the sole boron-containing product. As compound 7 is the monomeric variant of organoselenide 3, 18-crown-6 promotes both product selectivity and solubility in a nonpolar solvent. Diselenide 5, which features a trans-bent B−Se−Se−B core, was directly isolated via reaction of 1 with Se 2 Cl 2 in THF. Computational modeling suggests that the formation of 5 proceeds via a radical mechanism. This was supported by an experiment demonstrating that the CAAC-borafluorene radical also reacts with SeCl 2 to yield 5 [CAAC = (2,6-diisopropylphenyl)-4,4-diethyl-2,2-dimethyl-pyrrolidin-5-ylidene]. Energy decomposition analysis of 5 indicates a covalent borafluorene−diselenide bond (ΔE int , −168.9 kcal mol −1 ). All of the new compounds were fully characterized via single-crystal X-ray diffraction and multinuclear nuclear magnetic resonance ( 1 H, 13 C, 11 B, and 77 Se).

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“…Another important class of compounds are the organoselenium ones, which are used both as intermediate in organic synthesis and in drug discovery . There are several methods to introduce selenium into organic molecules, which include the use of nucleophilic, electrophilic and radical Se‐centered reagents …”

Section: Introductionmentioning

confidence: 99%