37859-32-8Relevant articles and documents
KOtBu-Promoted Halogen-Bond-Assisted Intramolecular C-S Cross-Coupling of o-Iodothioanilides for the Synthesis of 2-Substituted Benzothiazoles
Nandy, Anuradha,Sekar, Govindasamy
, p. 15825 - 15834 (2021/11/01)
An efficacious and mild KOtBu-promoted intramolecular C-S cross-coupling of ortho-iodothioanilides in conjunction with a catalytic quantity of phenanthroline as an additive has been described for the convenient synthesis of 2-substituted benzothiazoles. The methodology is suitable for attaining a wide variety of 2-alkyl- and 2-aryl-substituted benzothiazoles. Single-crystal XRD, DFT calculations, NMR, and UV studies suggest that halogen bonds between the units of ortho-iodothioanilides may assist in the electron transfer process.
Photocatalytic synthesis method of C2 substituted 2H-benzothiazole benzylated derivative
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Paragraph 0016; 0029-0030, (2020/12/10)
The invention discloses a photocatalytic synthesis method of a C2 substituted 2H-benzothiazole benzylated derivative. The photocatalytic synthesis method comprises the following steps of: mixing 2H-benzothiazole with substituted methyl benzene; adding an oxidizing agent Selectfluor, an additive trifluoroacetic acid and a solvent acetonitrile, carrying out a normal temperature stirring reaction under the protection of nitrogen and the irradiation of an LED blue light lamp, carrying out TLC monitoring until the reaction is finished, and carrying out separation and purification on the reaction liquid to obtain the C2 substituted 2H-benzothiazole benzylated derivative. The new method for synthesizing the C2 substituted 2H-benzothiazole benzylated derivative through visible light induction by taking Selectfluor as an oxidizing agent, trifluoroacetic acid as an additive and acetonitrile as a solvent is high in atom economy, simple in catalytic system, good in product yield, wide in substraterange and suitable for popularization and application.
Metal-Free Halogen(I) Catalysts for the Oxidation of Aryl(heteroaryl)methanes to Ketones or Esters: Selectivity Control by Halogen Bonding
Guha, Somraj,Sekar, Govindasamy
supporting information, p. 14171 - 14182 (2018/09/10)
Metal-free halogen(I) catalysts were used for the selective oxidation of aryl(heteroaryl)methanes [C(sp3)?H] to ketones [C(sp2)=O] or esters [C(sp3)?O]. The synthesis of ketones was performed with a catalytic amount of NBS in DMSO solvent. Experimental studies and density functional theory (DFT) calculations supported the formation of halogen bonding (XB) between the heteroarene and N-bromosuccinimide, which enabled imine–enamine tautomerism of the substrates. No additional activator was required for this crucial step. Isotope-labeling and other supporting experiments suggested that a Kornblum-type oxidation with DMSO and aerobic oxygenation with molecular oxygen took place simultaneously. A background XB-assisted electron transfer between the heteroarenes and halogen(I) catalysts was responsible for the formation of heterobenzylic radicals and, thus, the aerobic oxygenation. For selective acyloxylation (ester formation), a catalytic amount of iodine was employed with tert-butyl hydroperoxide in aliphatic carboxylic acid solvent. Several control reactions, spectroscopic studies, and Time-Dependent Density Functional Theory (TD–DFT) calculations established the presence of acetyl hypoiodite as an active halogen(I) species in the acetoxylation process. With the help of a selectivity study, for the first time we report that the strength of the XB interaction and the frontier orbital mixing between the substrates and acyl hypoiodites determined the extent of the background electron-transfer process and, thus, the selectivity of the reaction.
