Vinyl-, allyl-, and phenylethynylsilanes. Effect of silicon on their reactions as dienophiles and the synthesis of phenylated phenyl- and benzylsilanes

Freeburger, M. E.; Spialter, Leonard

doi:10.1021/jo00828a023

Cited by 26 publications

(25 citation statements)

References 7 publications

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“…All commercial reagents were used as received. Bis(phenyleth-A C H T U N G T R E N N U N G ynyl)dimethylsilane [68] was obtained by the reaction of dimethyldichlorosilane and phenylethynyllithium, which was prepared from nBuLi and phenylacetylene in ether.…”

Section: Methodsmentioning

confidence: 99%

Experimental and Theoretical Studies of Magnetic Exchange in Silole‐Bridged Diradicals

Roques

Gerbier

Schatzschneider

et al. 2006

Chemistry A European J

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Five bis(tert-butylnitroxide) diradicals connected by a silole (7 a-d) or a thiophene (12) ring as a coupler were studied. Compound 12 crystallizes in the orthorhombic space group Pna2(1) with a = 20.752(5), b = 5.826(5), and c = 34.309(5) A. X-ray crystal structure determination, electronic spectroscopy, variable-temperature EPR spectroscopy, SQUID measurements and DFT computations (UB3LYP/6-31+G*) were used to study the molecular conformations and electronic spin coupling in this series of molecules. Whereas compounds 7 b, 7 c, and 7 d are quite stable both in solution and in the solid state, 7 a and 12 undergo a partial electronic rearrangement to both a diamagnetic quinonoidal form and a monoradical species owing to the fact that they correspond to the open form of a pi-conjugated Kekulé structure. In the solid state, magnetic measurements indicate that the diradicals are all antiferromagnetically coupled, as expected from their topology. These interactions are best reproduced by means of a "Bleaney-Bowers" model that gives values of J = -142.0 cm(-1) for 7 a, -1.8 cm(-1) for 7 b, -1.3 cm(-1) for 7 c, -4.2 cm(-1) for 7 d, and -248.0 cm(-1) for 12. The temperature dependence of the EPR half-field transition in frozen dichloromethane solutions is consistent with singlet ground states and thermally accessible triplet states for diradicals 7 b, 7 c, and 7 d with DeltaE(T-S) values of 3.48, 2.09, and 8 cm(-1), respectively. No evidence of a populated triplet state was found for diradicals 7 a and 12. Similarities between the DeltaE(T-S) and J values (DeltaE(T-S) = -2 J) clearly show the intramolecular origin of the observed antiferromagnetic interaction. Analyses of the data with a "Karplus-Conroy"-type equation enabled us to establish that the silole ring, as a whole, allows a more efficient magnetic coupling of the two nitroxide radicals attached to its 2,5-positions than the thiophene ring. This superiority probably originates from the nonaromaticity of the silole which thus permits a better magnetic interaction through it. DFT calculations also support the experimental results, indicating that the magnetic exchange pathway preferentially involves the carbon pi system of the silole.

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Section: Methodsmentioning

confidence: 99%

Experimental and Theoretical Studies of Magnetic Exchange in Silole‐Bridged Diradicals

Roques

Gerbier

Schatzschneider

et al. 2006

Chemistry A European J

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“…Trimethylsilyl-, triethylsilyl-, triphenylsilyl-, and triethylgermyl-phenylacetylenes 10-13 were prepared by literature methods [55,56]. Triethylbromogermane was synthesized according to the literature [57].…”

Section: Experimental General Commentsmentioning

confidence: 99%

Bromination of silatranyl‐, germatranyl‐, silyl‐, and germyl‐phenylacetylenes

Selina

Karlov

Gauchenova

et al. 2004

Heteroatom Chemistry

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“…Electron impact mass spectra were analysed using a Varian mass spectrometer. HGaCl 2 , [13] EtLi, [33] PhÀ CC-SiPh 3 (1 a), [34] PhC(H)=CA C H T U N G T R E N N U N G (SiPh 3 )GaCl 2 (2 a) [12] …”

Section: Methodsmentioning

confidence: 99%

Vinylgallium and Alkyllithium Compounds: Transmetalation and Generation of Oligolithium Cages

Uhl

Kovert

Layh

et al. 2011

Chemistry A European J

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Vinylgallium compounds [C(6)H(6-n){(H)C=C(SiR(2) R')-GaR''(2)}(n ] (3, R=Ph, Me; R'=Ph, Me; R''=tBu, Et; n=1, 2) are easily accessible by hydrogallation of the corresponding alkynylbenzene derivatives with H-GaCl(2) and subsequent reaction with alkyllithium derivatives. Treatment of 3 with an excess amount of tert-butyl- or ethyllithium yielded by transmetalation and ortho-deprotonation of the aromatic rings the unprecedented solvent-free oligolithium cluster compounds [{(C(6)H(4)Li)HC=C(SiPh(3))Li}(2)(tBuLi)(2)] (4), [{(C(6)H(4)Li)HC=C(SiPh(2)Me)Li}(4)] (5) and [{(C(6)H(3)Li){HC=C(SiMe(3))Li}(2)}(3)] (6) in moderate yields. Their solid-state structures revealed the presence of unique molecular lithium clusters with 6, 8, or 9 lithium atoms that may be derived from two edge-sharing Li(4) tetrahedra (4), three Li(4) tetrahedra in a chain joined by two common edges (5) or a tricapped trigonal prism of lithium atoms (6).

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Vinyl-, allyl-, and phenylethynylsilanes. Effect of silicon on their reactions as dienophiles and the synthesis of phenylated phenyl- and benzylsilanes

Cited by 26 publications

References 7 publications

Experimental and Theoretical Studies of Magnetic Exchange in Silole‐Bridged Diradicals

Experimental and Theoretical Studies of Magnetic Exchange in Silole‐Bridged Diradicals

Bromination of silatranyl‐, germatranyl‐, silyl‐, and germyl‐phenylacetylenes

Vinylgallium and Alkyllithium Compounds: Transmetalation and Generation of Oligolithium Cages

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