130-03-0Relevant academic research and scientific papers
γ-Radiolysis of Aqueous Benzothiophene Solutions
Feng, Paul Y.,Patel, Kundan,Kaplan, Louis,Matheson, Max S.
, p. 2098 - 2103 (1981)
γ-Radiolysis of aqueous benzothiophene solutions saturated with N2O has been studied.In the absence of other reagents, the only products detected are 2- and 3-hydroxybenzothiophene and their corresponding lactonic and ketonic tautomers and a small amount of dimeric species.In the presence of potassium hexacyanoferrate or sodium hydroxide, however, products attributable to hydroxylation at all six available carbon sites are detected and dimer formation is reduced.Analysis of the experimental data suggests that both benzothiophene and its hydroxylation products are efficient scavengers for the radiation-produced OH radicals and that the initial yield of hydroxylation products is equal to that of hydroxyl radicals.Consistent with the electrophilic characteristics of the OH radical, k(OH+C8H6S):k(OH+C8H5SOH)=0.5+/-0.1.All six available carbon sites are capable of forming OH adducts, but the radicals formed by addition to the 4, 5, 6, and 7 positions tend to revert to the original compound or its ion in a neutral or acidic medium.In the case of the adducts formed by addition to the thiophene ring, on the other hand, the 3 position is seen to be favored, possibly as the result of the preservation of the aromatic benzene resonance structure.
REVERSIBLE CARBON PROTONATION IN THE HYDROLYSIS OF HETEROCYCLIC ENOL METHYL ETHERS
Capon, Brian,Kwok, Fu-Chiu
, p. 69 - 76 (1987)
The kinetics of the hydronium-ion catalysed hydrolysis of the following heterocyclic methyl enol ethers have been measured: 3-methoxybenzofuran, 3-methoxybenzothiophene, 3-methoxyindole, 3-methoxy-1-methylindole, 3-methoxyfuran, 3-methoxythiophene, and 2-methoxythiophene.On the basis of the solvent isotope effect kH/kD = 3.08 and the failure to detect deuterium exchange when the solvent was CD3CN:D2O (9:1 v/v) it was concluded that the rate limiting step in the hydrolysis of 3-methoxybenzofuran is C-protonation.The effect of the ring-oxygen atom was measured by comparing the rate of hydrolysis of 3-methoxybenzofuran with that of 3-methoxyindene which occurs 2100 times faster.In contrast to the behaviour of 3-methoxybenzofuran the isotope effects, kH/kD, for the hydrolyses of 3-methoxyfuran, 3-methoxythiophene, 3-methoxyindole, 3-methoxy-1-methylindole and 2-methoxythiophene are ca 0.4 - 0.5 and deuterium exchange is much faster than hydrolysis when the solvent is CD3CN:D2O (9:1 v/v).It was therefore concluded that with these compound C-protonation is rapid and reversible and that slow step is attack by water on the intermediate cation.
Does aromaticity in a reaction product increase or decrease the intrinsic barrier? Kinetics of the reversible deprotonation of benzofuran-3(2H)-one and benzothiophene-3(2H)-one
Bernasconi, Claude F.,Perez-Lorenzo, Moises
, p. 2704 - 2712 (2007)
A kinetic study of the reversible deprotonation of benzofuran-3(2H)-one (3H-O) and benzothiophene-3(2H)-one (3H-S) by amines and hydroxide ion in water at 25 °C is reported. The respective conjugate bases, 3--O and 3--S, represent benzofuran and benzothiophene derivatives, respectively, and thus are aromatic. The main question addressed in this paper is whether this aromaticity has the effect of enhancing or lowering intrinsic barriers to proton transfer. These intrinsic barriers were either determined from Bronsted plots for the reactions with amines or calculated on the basis of the Marcus equation for the reaction with OH-; they were found to be lower for the more highly aromatic benzothiophene derivative, indicating that aromaticity lowers the intrinsic barrier. It is shown that the reduction in the intrinsic barrier is not an artifact of other factors such as inductive, steric, resonance, polarizability, and π-donor effects, although these factors affect the intrinsic barriers in a major way. Our results imply that aromatic stabilization of the transition state is ahead of proton transfer; this contrasts with simple resonance effects, which typically lag behind proton transfer at the transition state, thereby increasing intrinsic barriers.
Integrated Synthesis of Thienyl Thioethers and Thieno[3,2-b]thiophenes via 1-Benzothiophen-3(2 H)-ones
Mitsudo, Koichi,Habara, Nanae,Kobashi, Yoshiaki,Kurimoto, Yuji,Mandai, Hiroki,Suga, Seiji
supporting information, p. 1947 - 1952 (2020/10/06)
A one-pot procedure for the synthesis of thienyl thioethers is described. Several thienyl thioethers were synthesized by a TfOH-promoted Friedel-Crafts-type cyclization, a subsequent nucleophilic attack by an arenethiol, and dehydration. This protocol was
Oxidized Hemithioindigo Photoswitches—Influence of Oxidation State on (Photo)physical and Photochemical Properties
K?ttner, Laura,Schildhauer, Monika,Wiedbrauk, Sandra,Mayer, Peter,Dube, Henry
supporting information, p. 10712 - 10718 (2020/07/27)
The photophysical and photochemical properties of sulfoxide and sulfone derivatives of hemithioindigo photoswitches are scrutinized and compared to the unoxidized parent chromophores. Oxidation results in significantly blue-shifted absorptions and mostly
Isomer-Specific Hydrogen Bonding as a Design Principle for Bidirectionally Quantitative and Redshifted Hemithioindigo Photoswitches
Zweig, Joshua E.,Newhouse, Timothy R.
supporting information, p. 10956 - 10959 (2017/08/21)
A new class of bidirectionally quantitative photoswitches based on the hemithioindigo (HTI) scaffold is reported. Incorporation of a pyrrole hydrogen-bond donor leads to a bathochromic shift allowing for quantitative bidirectional isomerization. Additionally, extending conjugation from the electron-rich pyrrole results in quantitative visible-light photoswitches, as well as photoswitches that isomerize with red and near-infrared light. The presence of the hydrogen bond leading to the observed redshift is supported by computational and spectroscopic evidence.
Twisted Hemithioindigo Photoswitches: Solvent Polarity Determines the Type of Light-Induced Rotations
Wiedbrauk, Sandra,Maerz, Benjamin,Samoylova, Elena,Reiner, Anne,Trommer, Florian,Mayer, Peter,Zinth, Wolfgang,Dube, Henry
supporting information, p. 12219 - 12227 (2016/10/03)
Controlling the internal motions of molecules by outside stimuli is a decisive task for the generation of responsive and complex molecular behavior and functionality. Light-induced structural changes of photoswitches are of special high interest due to the ease of signal application and high repeatability. Typically photoswitches use one reaction coordinate in their switching process and change between two more or less-defined states. Here we report on new twisted hemithioindigo photoswitches enabling two different reaction coordinates to be used for the switching process. Depending on the polarity of the solvent, either complete single bond (in DMSO) or double bond (in cyclohexane) rotation can be induced by visible light. This mutually independent switching establishes an unprecedented two-dimensional control of intramolecular rotations in this class of photoswitches. The mechanistic explanation involves formation of highly polar twisted intramolecular charge-transfer species in the excited state and is based on a large body of experimental quantifications, most notably ultrafast spectroscopy and quantum yield measurements in solvents of different polarity. The concept of pre-twisting in the ground state to open new, independent reaction coordinates in the excited state should be transferable to other photoswitching systems.
Catalysis of the acylation of aromatic derivatives by metallic tosylates
Morizur, Vincent,Szafranek, Jessica,Bonhomme, Dominique,Olivero, Sandra,Desmurs, Jean Roger,Du?ach, Elisabet
supporting information, p. 6813 - 6817 (2015/08/24)
A series of metallic tosylates were prepared by ultrasonic metal activation and were further used as efficient catalysts for the acylation of aromatic derivatives.
Making fast photoswitches faster - Using hammett analysis to understand the limit of donor-acceptor approaches for faster hemithioindigo photoswitches
Maerz, Benjamin,Wiedbrauk, Sandra,Oesterling, Sven,Samoylova, Elena,Nenov, Artur,Mayer, Peter,De Vivie-Riedle, Regina,Zinth, Wolfgang,Dube, Henry
, p. 13984 - 13992 (2016/02/18)
Hemithioindigo (HTI) photoswitches have a tremendous potential for biological and supramolecular applications due to their absorptions in the visible-light region in conjunction with ultrafast photoisomerization and high thermal bistability. Rational tail
Continuous-flow synthesis of functionalized phenols by aerobic oxidation of grignard reagents
He, Zhi,Jamison, Timothy F.
supporting information, p. 3353 - 3357 (2014/04/03)
Phenols are important compounds in chemical industry. An economical and green approach to phenol preparation by the direct oxidation of aryl Grignard reagents using compressed air in continuous gas-liquid segmented flow systems is described. The process tolerates a broad range of functional groups, including oxidation-sensitive functionalities such as alkenes, amines, and thioethers. By integrating a benzyne-mediated in-line generation of arylmagnesium intermediates with the aerobic oxidation, a facile three-step, one-flow process, capable of preparing 2-functionalized phenols in a modular fashion, is established. Putting on airs: Aerobic oxidation of (hetero)aryl Grignard reagents using compressed air proceeds with a gas-liquid continuous-flow system, thus enabling preparation of fucntionalized phenols. By integrating an in-line generation of ArMgBr intermediates with the aerobic oxidation, ortho-functionalized phenols can be assembled. The method demonstrates good functional-group (FG) compatibility, mild reaction conditions, and short reaction times.
