3721-17-3Relevant articles and documents
On the question of cyclopropylidene intermediates in cyclopropene-to-allene rearrangements - Tetrakis(trimethylsilyl)cyclopropene, 3-alkenyl-1,2,3-tris(trimethylsilyl)cyclopropenes, and related model compounds
De Meijere, Armin,Faber, Dietmar,Heinecke, Ute,Walsh, Robin,Mueller, Thomas,Apeloig, Yitzhak
, p. 663 - 680 (2001)
Several tetrasubstituted cyclopropenes have been prepared and their pyrolyses and photolyses have been investigated. Tetrakis(trimethylsilyl)cyclopropene (10), which was obtained in 25% yield from tris(trimethylsilyl)cyclopropenylium hexachloroantimonate (9), gave tetrakis(trimethylsilyl)allene (12) as the sole product both thermally and photochemically. Kinetic studies in [D8]toluene indicated first-order behavior with Arrhenius parameters log(A/s-1) = 11.75±1.20 and Ea = (37.5±2.5) kcal mol-1. All three new 3-alkenyl-1,2,3-tris(trimethylsilyl)cyclopropenes (17a-c, with C1-, C2-, and C3-alkenyl groups as tethers, respectively) gave allenes upon irradiation, but thermally only two (17a, 17c) gave allenes, whilst 17b yielded a bicyclo[4.1.0]hept-3-ene derivative 22 as a result of an intramolecular ene reaction. Photolyses of two further cyclopropenes (33a,b) bearing 1,2-bis(alkenyldimethylsilyl) substituents also gave the corresponding allenes as the sole products. For none of these tethered cyclopropenes was a product found that could have originated from intramolecular trapping of a cyclopropylidene intermediate. Quantum mechanical (ab initio) calculations have been carried out on the silyl-substituted cyclopropene model compounds 3,3-dimethyl-1-silyl- (36a), 3,3-dimethyl-1,2-disilyl- (37), and tetrasilylcyclopropene (38) at the QCISD(T)/6-311G*//B3LYP/6-311G* + ZPVE level of theory, and on 3,3-dimethyl-1-(trimethylsilyl)cyclopropene (36b) at the B3LYP/6-311G*//B3LYP/ 6-311G* + ZPVE level. These calculations provided us with detailed energy surfaces for the potential pyrolysis pathways. Although the potential cyclopropylidene species in these rearrangements are significantly stabilized, for none of the systems was this sufficient to permit isomerization via these intermediates. 36b is calculated to rearrange via a vinylidene intermediate to give 3-methyl-1-trimethylsilyl-1-butyne (47), in agreement with experiment. Comparison of the calculations for 36a and 36b shows that H3Si- is a poor model for an Me3Si- substituent in these rearrangements. When an appropriate correction is applied, the calculations on disilyl-(37) and tetrasilylcyclopropenes (38) are consistent with the experimental findings that the trimethylsilyl-substituted cyclopropenes 48 and 10 form allenes 49 and 12, respectively, via vinylcarbene-type intermediates. These findings considerably extend our understanding of silyl group substituent effects on the various intermediates involved in cyclopropene rearrangements. Wiley-VCH Verlag GmbH, 2001.
Visiting the Limits between a Highly Strained 1-Zirconacyclobuta-2,3-diene and Chemically Robust Dizirconacyclooctatetraene
Rei?, Fabian,Rei?, Melanie,Spannenberg, Anke,Jiao, Haijun,Baumann, Wolfgang,Arndt, Perdita,Rosenthal, Uwe,Beweries, Torsten
supporting information, p. 5667 - 5674 (2018/03/21)
The reaction of the allene precursor Li2(Me3SiC3SiMe3) with [Cp2ZrCl2] (Cp=cyclopentadienyl) was examined. The selective formation of hitherto unknown linear, allene-bridged dizirconocene complexes [(Cp2ZrCl)2{?μ-(Me3Si)C3(SiMe3)?}] and [(Cp2Zr)2{?μ-(Me3Si)C3(SiMe3)?}2] was observed. Upon σ coordination of the allenediyl unit to {Cp2Zr}, pyrophoric Li2(Me3SiC3SiMe3) is tamed stepwise to yield a surprisingly robust 1,5-dizirconacyclooctatetra-2,3,6,7-ene with cumulated double bonds. This complex is unexpectedly inert against moisture, air, water and acetone. Surprisingly, it degrades under MS conditions to give the highly strained 1-zirconacyclobuta-2,3-diene. All compounds isolated have been fully characterised and the molecular structures are discussed. The stability and reactivity of these complexes are rationalised by DFT computations.
Synthesis, Properties, and Reactions of Hexasilyl-3,3'-bicyclopropenyls and Related Compounds
Sakamoto, Kenkichi,Saeki, Takuya,Sakurai, Hideki
, p. 1675 - 1678 (2007/10/02)
Silylation of tetrachlorocyclopropene with trialkylchlorosilanes and magnesium in the presence of HMPA gave hexasilyl-3,3'-bicyclopropenyls or conjugated polymers containing both silylcyclopropene and silylallene moieties.Some reactions of these compounds were described.
A Facile Synthesis of Tetrakis(trimethylsilyl)butatriene Properties and Cycloadditions
Sakurai, Hideki,Kudo, Muneo,Sakamoto, Kenkichi,Nakadaira, Yasuhiro,Kira, Mitsuo,Sekiguchi, Akira
, p. 1441 - 1444 (2007/10/02)
Tetrakis(trimethylsilyl)butatriene was readily prepared by flash vacuum pyrolysis of hexakis(trimethylsilyl)-2-butyne.The physical and chemical properties of the butatriene are described.
UNE VOIE D'ACCES RAPIDE ET PRATIQUE AU TETRAKIS(TRIMETHYLSILYL)-ALLENE ET AU BIS(TRIMETHYLSILYL)-1,3 PROPYNE
Bennetau, Bernard,Youhouvoulou N'Gabe, Denis,Dunogues, Jacques
, p. 3813 - 3816 (2007/10/02)
Complete silylation of hexachlorobenzene using the Me3SiCl/Li/THF reagent at 0oC quantitatively affords tetrakis(trimethylsilyl)allene.This last upon a double protodesilylation with F3CCOOH at 0o, leads to the quantitative formation of 1,3-bis(trimethylsilyl)propyne via the 1,3,3-tris(trimethylsilyl)propyne.
