Four-membered rings from isocyanides: Developments since the mid 1980s

Moderhack, Dietrich

doi:10.3998/ark.5550190.p008.224

Cited by 8 publications

(3 citation statements)

References 63 publications

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“…The addition of isonitriles to inorganic homocycles has very limited precedence . Weidenbruch reported the oxidative addition of isonitriles into the Si–Si bonds of cyclotrisilanes and the Ge–Ge bonds of cyclotrigermanes to give ring-expansion products with a Si 3 C or Ge 3 C framework. , Sekiguchi and Scheschkewitz have reported the oxidative addition of isonitriles to cyclotrisilenes .…”

Section: Resultsmentioning

confidence: 99%

Influence of Ring Strain and Bond Polarization on the Ring Expansion of Phosphorus Homocycles

et al. 2017

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Heterolytic cleavage of homoatomic bonds is a challenge, as it requires separation of opposite charges. Even highly strained homoatomic rings (e.g., cyclopropane and cyclobutane) are kinetically stable and do not react with nucleophiles or electrophiles. In contrast, cycloalkanes bearing electron-donating/withdrawing substituents on adjacent carbons have polarized C-C bonds and undergo numerous heterolytic ring-opening and expansion reactions. Here we show that upon electrophile activation phosphorus homocycles exhibit analogous reactivity, which is modulated by the amount of ring strain and extent of bond polarization. Neutral rings (BuP), 1, or (BuP), 2, show no reactivity toward nitriles, but the cyclo-phosphinophosphonium derivative [(BuP)Me], [3Me], undergoes addition to nitriles giving five-membered PCN heterocycles. Because of its lower ring strain, the analogous four-membered ring, [(BuP)Me], [4Me], is thermodynamically stable with respect to cycloaddition with nitriles, despite similar P-P bond polarization. We also report the first example of isonitrile insertion into cyclophosphines, which is facile for polarized derivatives [3Me] and [4Me], but does not proceed for neutral 1 or 2, despite the calculated exothermicity of the process. Finally, we assessed the reactions of [4R] R = H, Cl, F toward 4-dimethylaminopyridine (dmap), which suggest that the site of nucleophilic attack varies with the extent of P-P bond polarization. These results deconvolute the influence of ring strain and bond polarization on the chemistry of inorganic homocycles and unlock new synthetic possibilities.

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Section: Resultsmentioning

confidence: 99%

Influence of Ring Strain and Bond Polarization on the Ring Expansion of Phosphorus Homocycles

et al. 2017

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“…While obvious because of the use of an alkane solvent, the methylene was verified to have originated from the methyl using 13 C labeling experiments (see Supporting Information). The coupling of isocyanides is well-known in organometallic chemistry; − however, the synthesis from intramolecular deprotonation of a methyl group has not been reported, to our knowledge. Similar products have been observed from isocyanide insertion and coupling, however these usually involve the cyclobutene group already being formed prior to insertion. − In 5 , the Th–N bond distances of 2.316(2) and 2.364(2) Å and the Th–C1 and Th–C2 bond distances are 2.781(2) and 2.784(2) Å.…”

Section: Resultsmentioning

confidence: 95%

Formation of an α-Diimine from Isocyanide Coupling Using Thorium(IV) and Uranium(IV) Phosphido–Methyl Complexes

et al. 2019

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To probe the reactivity of two potential sites at tetravalent thorium and uranium metal centers, we examined the monophosphido methyl complexes, (C5Me5)2An(CH3)[P(SiMe3)(Mes)], An = Th, U; Mes = 2,4,6-Me3C6H2. Reaction of these mixed ligand complexes with one, two, and three (or excess) equivalents of t BuNC was explored. When (C5Me5)2An(CH3)[P(SiMe3)(Mes)] is treated with one equivalent of t BuNC, the iminoacyl products, (C5Me5)2An[η2- t BuNCCH3][P(SiMe3)(Mes)], are formed. Using three equivalents (or excess) of t BuNC results in the formation of an α-diimine moiety, (C5Me5)2An[κ2-(N,N)–N( t Bu)CCN( t Bu)CN( t Bu)CH2]. When two equivalents of t BuNC are added, only the mono-insertion or α-diimine was observed in a 3:1 ratio. Density functional theory calculations were carried out to determine the lowest energy pathway in the formation of the α-diimine product via the iminoacyl complex.

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“…A recent paper corroborates this hypothesis, demonstrating that isocyanides exist predominantly in the carbenic form . Although [3 + 1] cycloaddition reactions between isocyanides and azomethine imines, nitrile ylides, and azomethine ylides have already been reported, there are no examples for a [3 + 1] cycloaddition reaction between nitrile N -oxides and isocyanides . Nitrile N -oxides 1 , as well as all of the 1,3-dipolar species, are ambiphilic dipoles characterized by a low energy difference between their HOMO or LUMO frontier orbitals, and they can hence react both with electron-rich or electron-poor dipolarophiles, as in this case the isocyanide 2 in its carbenic nature.…”

Section: Introductionmentioning

confidence: 93%

Multicomponent Reaction of Z-Chlorooximes, Isocyanides, and Hydroxylamines as Hypernucleophilic Traps. A One-Pot Route to Aminodioximes and Their Transformation into 5-Amino-1,2,4-oxadiazoles by Mitsunobu–Beckmann Rearrangement

et al. 2015

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Synthetically useful aminodioximes are prepared via a novel three-component reaction among Z-chlorooximes, isocyanides, and hydroxylamines by exploiting the preferential attack of isocyanides to nitrile N-oxides via a [3 + 1] cycloaddition reaction. The results of quantum mechanical studies of the reaction mechanism are also discussed. Furthermore, the one-pot conversion of aminodioximes to 1,2,3-oxadiazole-5-amines via Mitsunobu-Beckmann rearrangement is reported for the first time.

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Four-membered rings from isocyanides: Developments since the mid 1980s

Abstract: Reactions of isocyanides with open-chain and cyclic substrates leading to four-membered rings are reviewed. The survey is intended to be illustrative rather than encyclopedic.

Cited by 8 publications

References 63 publications

Influence of Ring Strain and Bond Polarization on the Ring Expansion of Phosphorus Homocycles

Influence of Ring Strain and Bond Polarization on the Ring Expansion of Phosphorus Homocycles

Formation of an α-Diimine from Isocyanide Coupling Using Thorium(IV) and Uranium(IV) Phosphido–Methyl Complexes

Multicomponent Reaction of Z-Chlorooximes, Isocyanides, and Hydroxylamines as Hypernucleophilic Traps. A One-Pot Route to Aminodioximes and Their Transformation into 5-Amino-1,2,4-oxadiazoles by Mitsunobu–Beckmann Rearrangement

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