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Type: Article × Subject: Heterocycles ×

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Now showing 1 - 4 of 4
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    On the Reactivity of Phosphaalumenes towards C−C Multiple Bonds
    (Weinheim : Wiley-VCH, 2023) Nees, Samuel; Wellnitz, Tim; Dankert, Fabian; Härterich, Marcel; Dotzauer, Simon; Feldt, Milica; Braunschweig, Holger; Hering‐Junghans, Christian
    Heterocycles containing group 13 and 15 elements such as borazines are an integral part of organic, biomedical and materials chemistry. Surprisingly, heterocycles containing P and Al are rare. We have now utilized phosphaalumenes in reactions with alkynes, alkenes and conjugated double bond systems. With sterically demanding alkynes 1,2-phosphaalumetes were afforded, whereas the reaction with HCCH or HCCSiMe3 gave 1,4-phosphaaluminabarrelenes. Using styrene saturated 1,2-phosphaalumates were formed, which reacted further with additional styrene to give different regio-isomers of 1,4-aluminaphosphorinanes. Using ethylene, a 1,4-aluminaphosphorinane is obtained, while with 1,3-butadiene a bicyclic system containing an aluminacyclopentane and a phosphirane unit was synthesized. The experimental work is supported by theoretical studies to shed light on the mechanism governing the formation of these heterocycles.
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    Tandem dinucleophilic cyclization of cyclohexane-1,3-diones with pyridinium salts
    (Frankfurt, M. : Beilstein-Institut zur Förderung der Chemischen Wissenschaften, 2013) Kiamehr, M.; Moghaddam, F.M.; Mkrtchyan, S.; Semeniuchenko, V.; Supe, L.; Villinger, A.; Langer, P.; Laroshenko, V.O.
    The cyclization of cyclohexane-1,3-diones with various substituted pyridinium salts afforded functionalized 8-oxa-10-aza-tricyclo[7.3.1.0 2,7]trideca-2(7),11-dienes. The reaction proceeds by regioselective attack of the central carbon atom of the 1,3-dicar-bonyl unit to 4-position of the pyridinium salt and subsequent cyclization by base-assisted proton migration and nucleophilic addition of the oxygen atom to the 2-position, as was elucidated by DFT computations. Fairly extensive screening of bases and additives revealed that the presence of potassium cations is essential for formation of the product.
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    Reduction of dichloro(diaza-phospha)stibanes – isolation of a donor-stabilized distibenium dication
    (London : Soc., 2016) Hinz, Alexander; Rothe, Julia; Schulz, Axel; Villinger, Alexander
    A reaction of antimonytrichloride SbCl3 with potassium bis(terphenylimino)phosphide K[(TerN)2P] smoothly afforded a novel class of mixed diazadipnictanes, namely dichloro(diaza-phospha)stibane [Ter2N2P(III)Sb(III)Cl2], which is considered to exist as open chain-like and cyclic isomers in an equilibrium. [Ter2N2PSbCl2] is a versatile starting material for reduction and halide abstraction experiments. Halide abstraction led to the formation of a cyclic diazastibaphosphenium cation [P(μ-NTer)2SbCl]+. Upon reduction of [Ter2N2PSbCl2], the transient existence of the novel mixed biradicaloid [P(μ-NTer)2Sb] was proven by a trapping experiment with an alkyne, while reduction in the absence of trapping agents afforded the eight-membered heterocycle [Sb2-{μ-(TerN)2P}2]. This constitutional isomer of a dimerized biradicaloid features a bonding situation that indicates the presence of a donor-stabilized [Sb2]2+ ion.
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    Novel naphthylpyridines from cobalt-catalyzed cyclotrimerization of a chiral diyne
    (Wien [u.a.] : Springer, 2017-11-28) Trommer, Volkmar; Fischer, Fabian; Hapke, Marko
    The concise synthesis of a novel chiral diyne substrate for the assembly of chiral naphthylpyridines was described and different conditions for the cobalt-catalyzed co-cyclotrimerization with nitriles investigated. The products are novel naphthylpyridines possessing configurationally stable biaryl axes.