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Semispectroscopic and Quantitative Structure-Property Relationship Estimates of the Equilibrium and Vibrationally Averaged Structure and Dipole Moment of 1-Buten-3-yne

Semispectroscopic and Quantitative Structure-Property Relationship Estimates of the Equilibrium and Vibrationally Averaged Structure and Dipole Moment of 1-Buten-3-yne. Tasi, Gyula; Szoeri, Milan; Csaszar, Attila G. (Department of Applied and Environmental Chemistry, University of Szeged, Szeged H-6720, Hung.). Journal of Physical Chemistry A, 109(21), 4824-4828 (English) 2005 American Chemical Society. CODEN: JPCAFH. ISSN: 1089-5639. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) Systematic quantum chem. calcns. have been performed to obtain precise ests. of the equil. and vibrationally averaged mol. structure and elec. dipole moment of vinylacetylene (VA, 1-buten-3-yne). Anharmonic (cubic and semi-diagonal quartic) MP2/cc-pVTZ force fields in normal coordinates were computed to account for anharmonic vibrational effects, including zero-point contributions to the rotational consts. and the elec. dipole moment. A simultaneous weighted least-squares structural refinement was performed, resulting in the best semispectroscopic est. of the re structure of VA. The refinement was based on exptl. measured ground-state rotational consts. of two isotopologs of VA cor. to equil. values using MP2/cc-pVTZ vibration-rotation interaction consts. and all-electron CCSD(T)/aug-cc-pVTZ structural constraints. The semispectroscopic re structure of VA agrees excellently with the high-level CCSD(T)/aug-cc-pVTZ ab initio structure. The most dependable, CCSD(T)/cc-pVQZ//CCSD(T)/aug-cc-pVTZ equil. elec. dipole moment of VA, in D, is ma = 0.4088, mb = 0.0004, and mc = 0. The vibrationally cor. a-component of 0.4214 D is in excellent agreement with one of the available exptl. values. The present anal. shows that mb is negligible even after vibrational correction. A simple quant. structure-property relationship (QSPR) model resulted in a highly similar est., 0.45 D, for the elec. dipole moment of VA.

Palladium-Catalyzed Asymmetric Hydrosilylation of 4-Substituted 1-Buten-3-ynes

Palladium-Catalyzed Asymmetric Hydrosilylation of 4-Substituted 1-Buten-3-ynes. Catalytic Asymmetric Synthesis of Axially Chiral Allenylsilanes. Han, Jin Wook; Tokunaga, Norihito; Hayashi, Tamio (Department of Chemistry Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan). Journal of the American Chemical Society, 123(51), 12915-12916 (English) 2001 American Chemical Society. CODEN: JACSAT. ISSN: 0002-7863. DOCUMENT TYPE: Journal CA Section: 29 (Organometallic and Organometalloidal Compounds) The first successful example of a prepn. of axially chiral allenylsilanes by asym. catalysis is presented. Thus, the asym. hydrosilylation of 5,5-dimethyl-1-hexen-3-yne catalyzed by a palladium complex of (+)-(S)-(R)-bisPPFOMe, (I) (synthetic prepn. given), gave (t-Bu)(SiCl3)C:C:CH(Me) in 59% yield and 85% ee. The prepd. allenyl(trichloro)silanes obtained were reacted with benzaldehyde to give the corresponding homopropargylic alcs.