107-19-7Relevant articles and documents
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Cherbuliez et al.
, p. 2180 (1967)
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Oka
, p. 562,563 (1962)
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Hatch et al.
, p. 654,657 (1950)
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Visible Light-Induced Oxygen Transfer from Nitrogen Dioxide to Ethyne and Propyne in a Cryogenic Matrix. 2. Mechanism and Regioselectivity
Harrison, James A.,Frei, Heinz
, p. 12152 - 12157 (1994)
The kinetics of visible ligth-induced oxidation of ethyne and propyne by NO2 in solid Ar has been monitored as a function of photolysis wavelength.CW dye and Ar ion laser emission was used for irradiation, and FT-infrared spectroscopy for the measurement of product growth.Determination of the wavelength dependence of quantum efficiencies from the kinetic measurements revealed that the photolysis threshold of HCCH + NO2 lies approximately 6 kcal mol-1 higher than that of CH3CCH + NO2.This and other parameters derived from the product growth measurements, and the formyl methyl iminoxy radical trapped in the case of the CH3CCH + NO2 reaction are interpreted in terms of a direct O transfer mechanism.The proposed path involves large-amplitude O transfer from photoexcited NO2 to the CC group to yield a transient ketocarbene.Formation of iminoxy radical is attributed to trapping of the ketocarbene by NO cage coproduct, which is in competition with Wolff rearrangement to yield ketene.From the structure of the iminoxy radical, it is inferred that the photoinduced O transfer from NO2 to the unsymmetrical CC bond of propyne is completely regioselective, leading exclusively to the carbene transient with oxygen at the terminal carbon.This regiochemical outcome is interpreted in terms of potential energy profiles for central and terminal carbon attack of the triple bond.
Study of the regioselectivity in the hydrotelluration of hydroxy alkynes
Stefani, Hélio A.,Cardoso, Lincoln D. G.,Valduga, Claudéte J.,Zeni, Gilson
, p. 167 - 172 (2001)
Vinylic tellurides were synthesized by the addition of organotellurols to acetylenic alcohols and the regioselectivity of the reaction was evaluated.
Visible Light-Induced Oxygen Transfer from Nitrogen Dioxide to Ethyne and Propyne in a Cryogenic Matrix. 1. Identification of Products
Harrison, James A.,Frei, Heinz
, p. 12142 - 12151 (1994)
Photochemical reaction of ethyne*NO2 and propyne*NO2 pairs isolated in solid Ar has been observed at wavelengths as long as 582 nm (HCCH*NO2) and 615 nm (CH3CCH*NO2).Continuous wave dye laser radiation was used to excite the reactants, and the chemistry was monitored by FT-infrared spectroscopy.In the case of ethyne + NO2, the sole products were CH2=C=O and NO.The reaction of NO2 with propyne gave methylketene plus a trapped intermediate, CH3C(=NO.)C(=O)H (formyl methyl iminoxy radical).Infrared spectra of this radical are reported for the first time.Product identification was based on D, 18O, and 15N isotopic substitution.Selective interconversion with tuned visible laser light revealed the presence of four conformers, most probably originating from isomerism about the C-C and the C=N bonds.Photoelimination of NO from the iminoxy radical was observed at wavelengths as long as 625 nm.Propynol and methylketene could be identified among the secondary photolysis products.
Regiospecific Synthesis of Calcium-Independent Daptomycin Antibiotics using a Chemoenzymatic Method
Mupparapu, Nagaraju,Lin, Yu-Hsin Cindy,Kim, Tae Ho,Elshahawi, Sherif I.
supporting information, p. 4176 - 4182 (2021/02/01)
Daptomycin (DAP) is a calcium (Ca2+)-dependent FDA-approved antibiotic drug for the treatment of Gram-positive infections. It possesses a complex pharmacophore hampering derivatization and/or synthesis of analogues. To mimic the Ca2+-binding effect, we used a chemoenzymatic approach to modify the tryptophan (Trp) residue of DAP and synthesize kinetically characterized and structurally elucidated regiospecific Trp-modified DAP analogues. We demonstrated that the modified DAPs are several times more active than the parent molecule against antibiotic-susceptible and antibiotic-resistant Gram-positive bacteria. Strikingly, and in contrast to the parent molecule, the DAP derivatives do not rely on calcium or any additional elements for activity.
Palladium-Catalyzed Selective Reduction of Carbonyl Compounds
Sarkar, Nabin,Mahato, Mamata,Nembenna, Sharanappa
, p. 2295 - 2301 (2020/05/18)
Two new examples of structurally characterized β-diketiminate analogues i.e., conjugated bis-guanidinate (CBG) supported palladium(II) complexes, [LPdX]2; [L= {(ArHN)(ArN)–C=N–C=(NAr)(NHAr)}; Ar = 2,6-Et2-C6H3], X = Cl (1), Br (2) have been reported. The synthesis of complexes 1–2 was achieved by two methods. Method A involves deprotonation of LH by nBuLi followed by the treatment of LLi (insitu formed) with PdCl2 in THF, which afforded compound 1 in good yield (75 %). In Method B, the reaction between free LH and PdX2 (X = Cl or Br) in THF allowed the formation of complexes 1 (Yield 73 %) and 2 (Yield 52 %), respectively. Moreover, these complexes were characterized thoroughly by several spectroscopic techniques (1H, 13C NMR, UV/Vis, FT-IR, and HRMS), including single-crystal X-ray structural and elemental analyses. In addition, we tested the catalytic activity of these complexes 1–2 for the hydroboration of carbonyl compounds with pinacolborane (HBpin). We observed that compound 1 exhibits superior catalytic activity when compared to 2. Compound 1 efficiently catalyzes various aldehydes and ketones under solvent-free conditions. Furthermore, both inter- and intramolecular chemoselectivity hydroboration of aldehydes over other functionalities have been established.