113709-90-3Relevant academic research and scientific papers
Practical thiol surrogates and protective groups for arylthiols for Suzuki-Miyaura conditions
Itoh, Takahiro,Mase, Toshiaki
, p. 2203 - 2206 (2007/10/03)
We have developed practical thiol surrogates and arylthiol protective groups for the Suzuki-Miyaura reaction. 2-Ethylhexyl-3-mercaptopropionate and 4-(2′-mercaptoethyl)pyridine were shown to be not only good thiol surrogates but also good protective groups for thiol. We have demonstrated toleration of these protective groups under aqueous Suzuki-Miyaura conditions.
Study of the ESI-mass spectrometry ionization mechanism of Fischer carbene complexes
Wulff, William D.,Korthals, Keith A.,Martinez-Alvarez, Roberto,Gomez-Gallego, Mar,Fernandez, Israel,Sierra, Miguel A.
, p. 5269 - 5277 (2007/10/03)
By means of deuterium-labeling experiments, we have carried out a systematic ESI-MS study to determine the mechanism of ESI ionization of alkenyl and alkynyl group 6 Fischer carbene complexes. These compounds can be ionized under ESI conditions only in the presence of additives such as hydroquinone (HQ) or tetrathiafulvalene (TTF). Our results demonstrate that in the ESI source an anion-radical is formed after the initial HQ- or TTF-mediated electron transfer to the metallic carbene complex. For alkenyl carbene complexes, this species evolves by extrusion of a hydrogen radical to form an allenylchromium anion that is detected as the [M - H]- ion in the mass spectrum. The preference for this mechanistic pathway could be rationalized by DFT calculations. In the case of alkynyl carbene complexes, experiments combining deuterated substrate, additive, and solvent demonstrate that the previously proposed allene-anion carbene complex is not formed. Instead, the H transfer from the ethoxy group in the anion radical, followed by extrusion of a hydrogen radical, leads to an allenyl anion that is detected in the ESI-MS as [M - H - CO]-.
Rapid Syntheses of Oligo(2,5-thiophene ethynylene)s with Thioester Termini: Potential Molecular Scale Wires with Alligator Clips
Pearson, Darren L.,Tour, James M.
, p. 1376 - 1387 (2007/10/03)
The syntheses of soluble oligo(3-ethyl-2,5-thiophene ethynylene)s via an iterative divergent/ convergent approach starting from 3-ethyl-2-(trimethylsilylethynyl)thiophene are described. The monomer, dimer, tetramer, octamer, and 16-mer were synthesized. The 16-mer is 100 A long in its minimized extended zigzag conformation. At each stage in the iteration, the length of the framework doubles. Only three sets of reaction conditions are needed for the entire iterative synthetic sequence: an iodination, a protodesilylation, and a Pd/Cu-catalyzed cross coupling. The oligomers were characterized spectroscopically and by mass spectrometry. The optical properties are presented which show that at the octamer stage, the optical absorbance maximum is nearly saturated. The size exclusion chromatography values for the number average weights, relative to polystyrene, illustrate the tremendous differences in the hydrodynamic volume of these rigid rod oligomers verses the random coils of polystyrene. These differences become quite apparent at the octamer stage. Attachment of thiol end groups, protected as the thioacetyl moieties, was achieved. These serve as binding sites for adhesion to gold surfaces. In some cases, one end of the oligomeric chains were capped with a thiol group so that the surface attachments to gold could be studied. In other cases, thiol groups were affixed to both ends of the molecular chains so that future conduction studies could be done between proximal metallic probes. The rigid rod conjugated oligomers may act as molecular wires in molecular scale electronic devices, and they also serve as useful models for understanding analogous bulk polymers.
Phenylethynyl: Matrix Isolation Electron Spin Resonance and Molecular Orbital Study
Kasai, Paul H.,McBay, Henry C.
, p. 5932 - 5934 (2007/10/02)
Electron spin resonance spectra of phenylethynyl radical generated in argon matrices were examined.Spectral analysis showed that the radical is a ? radical PhC.=C: as had been found earlier for the same radical generated in solution.An EHT-MO s
