- Silicon-carbon unsaturated compounds. 62. Reactions of silenes produced thermally from pivaloyl- and adamantoyltris(trimethylsilyl)silane with mono(silyl)acetylenes
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Thermolysis of pivaloyltris(trimethylsilyl)silane (1a) with tert-butyldimethylsilylacetylene at 120°C gave 2-tert-butyl-3-tert-butyldimethylsilyl-2-trimethylsiloxy-1,1-bis(trimethylsilyl) -1-silacyclobut-3-ene (2a). Similar treatment of adamantoyltris(trimethylsilyl)silane (1b) at 120°C produced 2-adamantyl-3-tert-butyldimethylsilyl-2-trimethylsiloxy-1,1-bis(trimethylsilyl)- 1-silacyclobut-3-ene (2b). Thermolysis of 1a with tert-butyldimethylsilylacetylene at 160°C, however, gave 1-tert-butyl-1-(tert-butyldimethylsilyl)-3-[(trimethylsiloxy)bis(trimethylsilyl) silyl]-1,2-propadiene (3a), along with 1:2 adduct (4a). Similar reaction of 1b gave 1-adamantyl-1-(tert-butyldimethylsilyl)-3-[(trimethylsiloxy)bis(trimethylsilyl) silyl]-1,2-propadiene (3b) similar to 3a, together with 1:2 adduct (4b). Thermolysis of 1a and 1b in the presence of dimethylphenylsilylacetylene or triphenylsilylacetylene at 120°C produced [2 + 2] cycloadducts arising from the reaction of silenes generated thermally from 1a and 1b with mono(silyl)acetylenes analogous 2a and 2b, along with small amounts of 1:2 adducts. At 160°C, the similar treatment of 1a and 1b afforded propadiene derivatives arising from the ring opening reactions of [2 + 2] cycloadducts, in addition to 1:2 adducts.
- Naka, Akinobu,Ishikawa, Mitsuo
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- Synthesis and Structural Diversity of Triaryl(phenylethyl)silanes
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Starting from trichloro(phenylethyl)silane, six differently fluorinated triaryl(phenylethyl)silanes were synthesized by salt elimination reactions and their structures were determined by X-ray diffraction analysis. Tris(pentafluorophenyl)(phenylethyl)silane reveals a folded structure due to intramolecular π-stacking interactions, while those with a lower degree of fluorination show either intermolecular π-stacking or no interplay between the aryl groups. A similar folded structure was observed for (4-methylphenethyl)tris(pentafluorophenyl)silane and [2-(naphth-2-yl)ethyl]tris(pentafluorophenyl)silane, both generated from the corresponding trichlorosilanes. In contrast, the inversely fluorinated [2-(pentafluorophenyl)ethyl]triphenylsilane only revealed intermolecular π-stacking interactions. Compounds with tetrafluoropyridyl substituents behave differently; with these compounds, π-stacking is only observed between the fluorinated units. All compounds were analyzed by NMR and IR spectroscopy, elemental analyses and single-crystal X-ray diffraction, and found to have strong H/C/N/F···F and N···C contacts.
- Linnemannst?ns, Marvin,Mitzel, Norbert W.,Neumann, Beate,Stammler, Hans-Georg
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p. 1025 - 1034
(2020/04/01)
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- Enantioselective Iridium-Catalyzed Allylation of Acetylenic Ketones via 2-Propanol-Mediated Reductive Coupling of Allyl Acetate: C14-C23 of Pladienolide D
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Highly enantioselective catalytic reductive coupling of allyl acetate with acetylenic ketones occurs in a chemoselective manner in the presence of aliphatic or aromatic ketones. This method was used to construct C14-C23 of pladienolide D in half the steps previously required.
- Brito, Gilmar A.,Jung, Woo-Ok,Yoo, Minjin,Krische, Michael J.
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supporting information
p. 18803 - 18807
(2019/11/19)
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- Fourfold Diels-Alder Reaction of Tetraethynylsilane
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A series of ethynylated silanes, including tetraethynylsilane was treated with tetraphenylcyclopentadienone at 300 8C under microwave irradiation to give the aromatized Diels-Alder adducts as sterically encumbered mini-dendrimers with up to 20 benzene rings. The sterically most congested adducts display red-shifted emission through intramolecular p-p interactions in the excited state.
- Geyer, Florian L.,Rode, Alexander,Bunz, Uwe H. F.
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p. 16448 - 16453
(2016/02/12)
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- Using triethynylphosphine ligands bearing bulky end caps to create a holey catalytic environment: Application to gold(I)-catalyzed alkyne cyclizations
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The synthesis, properties and catalytic uses of phosphinoalkynes bearing bulky end caps at the alkyne termini, that is, tris[(triarylsilyl)ethynyl]phosphines are reported. The most salient feature of the new phosphines is the holey molecular shape possess
- Ochida, Atsuko,Ito, Hideto,Sawamura, Masaya
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p. 16486 - 16487
(2007/10/03)
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- SILICON-DIRECTED NAZAROV CYCLIZATIONS - IV FURTHER STUDIES IN STEREOCHEMICAL CONTROL
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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
- Denmark, Scott E.,Habermas, Karl L.,Hite, Gary A.,Jones, Todd K.
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p. 2821 - 2829
(2007/10/02)
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