17156-64-8Relevant articles and documents
Mechanism of host-guest complex formation and identification of intermediates through NMR titration and diffusion NMR spectroscopy
Lamm, Jan-Hendrik,Niermeier, Philipp,Mix, Andreas,Chmiel, Jasmin,Neumann, Beate,Stammler, Hans-Georg,Mitzel, Norbert W.
, p. 7938 - 7942 (2014)
The formation of host-guest (H-G) complexes between 1,8- bis[(diethylgallanyl)ethynyl]anthracene (H) and the N-heterocycles pyridine and pyrimidine (G) was studied in solution using a combination of NMR titration and diffusion NMR experiments. For the latter, diffusion coefficients of potential host-guest structures in solution were compared with those of tailor-made reference compounds of similar shape (synthesized and characterized by NMR, HRMS, and in part XRD). Highly dynamic behavior was observed in both cases, but with different host-guest species and equilibria. With increasing concentrations of the pyridine guest, the equilibrium H2?H 2κ1-G1?HG2 is observed (in the second step a host dimer coordinates one guest molecule); for pyrimidine the equilibrium H2→H1κ2-G 1?HG2 is observed (the formation of a 1:1 aggregate is the second step). Dynamic host-guest complexation was studied using a new combination of NMR titration and diffusion NMR experiments. The host is the bidentate 1,8-bis[(diethylgallanyl)ethynyl]anthracene, the guests are pyrimidine and pyridine. The analysis of the diffusion NMR experiments requires tailor-made reference compounds of the same shape for comparison.
Three-coordinate copper(II) alkynyl complex in C-C bond formation: The sesquicentennial of the glaser coupling
Warren, Timothy H.,Bakhoda, Abolghasem,Okoromoba, Otome E.,Greene, Christine,Boroujeni, Mahdi Raghibi,Bertke, Jeffery A.
supporting information, p. 18483 - 18490 (2020/11/27)
Copper(II) alkynyl species are proposed as key intermediates in numerous Cu-catalyzed C-C coupling reactions. Supported by a β-diketiminate ligand, the three-coordinate copper(II) alkynyl [CuII]-C≡CAr (Ar = 2,6-Cl2C6H3) forms upon reaction of the alkyne H-C≡CAr with the copper(II) tertbutoxide complex [CuII]-OtBu. In solution, this [CuII]-C≡CAr species cleanly transforms to the Glaser coupling product ArC≡C-C≡CAr and [CuI](solvent). Addition of nucleophiles R′C≡C-Li (R′ = aryl, silyl) and Ph-Li to [CuII]-C≡CAr affords the corresponding Csp-Csp and Csp-Csp2 coupled products RC≡C-C≡CAr and Ph-C≡CAr with concomitant generation of [CuI](solvent) and {[CuI]-C≡CAr}-, respectively. Supported by density functional theory (DFT) calculations, redox disproportionation forms [CuIII](C≡CAr)(R) species that reductively eliminate R-C≡CAr products. [CuII]-C≡CAr also captures the trityl radical Ph3C· to give Ph3C-C≡CAr. Radical capture represents the key Csp-Csp3 bond-forming step in the copper-catalyzed C-H functionalization of benzylic substrates R-H with alkynes H-C≡CR′ (R′ = (hetero)aryl, silyl) that provide Csp-Csp3 coupled products R-C≡CR via radical relay with tBuOOtBu as oxidant.
Studies on the thermal ring-opening reactions of cis-3,4-bis(organosilyl) cyclobutenes
Hasegawa, Munehiro,Murakami, Masahiro
, p. 3764 - 3769 (2008/02/05)
(Chemical Equation Presented) Three cis-3,4-bis(organosilyl)cyclobutenes were synthesized, and their thermal ring-opening reactions were studied. The ring-opening reaction of cis-3,4-bis(trimethylsilyl)cyclobutene proceeded remarkably faster than that of
1,3-Dipolar cycloadditions of silicon and tin alkynes and alkenes. Regiospecific synthesis of silyl and stannylpyrazoles and pyrazolines
González-Nogal, Ana M.,Calle, Mariola,Cuadrado, Purificación,Valero, Raquel
, p. 224 - 231 (2007/10/03)
Silicon and tin 3-, 3,5-, and 3,4,5-metalated pyrazoles have been synthesized by 1,3-dipolar cycloadditions of silyl-, disilyl-, and silylstannylacetylenes with N-phenylsydnone or trimethylsilyldiazomethane. On the other hand, 1- and 2-pyrazolines monomet
Acid-catalyzed cyclization of vinylsilanes bearing a hydroxy group: A new method for stereoselective synthesis of disubstituted tetrahydrofurans
Miura,Okajima,Hondo,Nakagawa,Takahashi,Hosomi
, p. 11348 - 11357 (2007/10/03)
In the presence of a catalytic amount of TsOH or TiCl4, (Z)-5-silyl-4-penten-1-ols ((Z)-1) are smoothly cyclized to 2-silylmethyl-substituted tetrahydrofurans. This cyclization is applicable to the construction of a tetrahydropyran ring. The silyl group and the geometry of the C-C double bond strongly influence the cychzation rate. TBDMS and benzyldimethylsilyl groups considerably accelerate the cyclization in comparison with a dimethylphenylsilyl group, and (E)-vinylsilanes show much lower reactivity than the corresponding (Z)-isomers. The cyclization proceeds by stereospecific syn addition of the hydroxy group. Vinylsilanes 17, 19, and 21, (Z)-5-silyl-4-penten-1-ols bearing a substituent on the methylene tether, smoothly undergo the acid-catalyzed cyclization to give trans-2,5-, cis-2,4-, and trans-2,3-disubstituted tetrahydrofurans, respectively, with moderate to high stereoselectivity. The silyl group of some cychzed products can be easily converted into a hydroxy group with stereochemical retention.
Synthesis of Allenylsilanes from Propargyl Carbamates
Fleming, Ian,Takaki, Ken,Thomas, Andrew P.
, p. 2269 - 2274 (2007/10/02)
Pent-3-yn-2-yl acetate (1) reacts with dimethyl(phenyl)silyl cuprate reagent to give a mixture of allenylsilane and propargylsilane.The corresponding N-phenylcarbamate (4) gives only the allenylsilane.Four other examples of this regioselective reaction are reported.The stereochemistry is largely syn.
SILICON-DIRECTED NAZAROV CYCLIZATIONS - IV FURTHER STUDIES IN STEREOCHEMICAL CONTROL
Denmark, Scott E.,Habermas, Karl L.,Hite, Gary A.,Jones, Todd K.
, p. 2821 - 2829 (2007/10/02)
The silicon-directed Nazarov cyclization was shown to proceed with good to excellent stereoselectivity in cyclohexenyl systems bearing a variety of ring substituents.In all cases the trans family of isomers predominated, and cis ring-fused products were f
