- Copper catalyzed three-component synthesis of benzothiazolones from o-iodoanilines, DMF, and potassium sulfide
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A copper catalyzed three-component reaction was developed for the synthesis of benzothiazolones. In the presence of CuBr2, the reaction of o-iodoanilines and K2S with DMF proceeded smoothly and generated the corresponding benzothiazolones with good isolated yields. DMF functioned both as the carbon monoxide source and as the reaction medium in this reaction.
- Yang, Yuan,Zhang, Xiaoyun,Zeng, Weilan,Huang, Hui,Liang, Yun
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Read Online
- Synthesis method of benzothiazolone compound
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The invention discloses an economical and mild. The method adopts o-iodoaniline, elemental sulfur and DMF as raw materials, so that the yield of a target product of up to 3 hours can be obtained only 90%, and the synthesis strategy is compatible with a wide range of functional groups.
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Paragraph 0018-0026; 0028-0029; 0034
(2021/11/03)
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- Experimental and theoretical studies on the thermal decomposition of heterocyclic nitrosimines
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A series of substituted 2-nitrosiminobenzothiazolines (2) were synthesized by the nitrosation of the corresponding 2-iminobenzothiazolines (6). Thermal decomposition of 2a-f and of the seleno analogue 7 in methanol and of 3-methyl-2-nitrosobenzothiazoline (2a) in acetonitrile, 1,4-dioxane, and cyclohexane followed first-order kinetics. The activation parameters for thermal deazetization of 2a were measured in cyclohexane (ΔH? = 25.3 ± 0.5 kcal/mol, ΔS? = 1.3 ± 1.5 eu) and in methanol (ΔH? = 22.5 ± 0.7 kcal/mol, ΔS? = -12.9 ± 2.1 eu). These results indicate a unimolecular decomposition and are consistent with a proposed stepwise mechanism involving cyclization of the nitrosimine followed by loss of N2. The ground-state conformations of the parent nitrosiminothiazoline (9a) and transition states for rotation around the exocyclic C=N bond, electrocyclic ring closure, and loss of N2 were calculated using ab initio molecular orbital theory at the MP2/6-31G* level. The calculated gas-phase barrier height for the loss of N2 from 9a (25.2 kcal/mol, MP4(SDQ, FC)/6-31G*//MP2/6-31G* + ZPE) compares favorably with the experimental barrier for 2a of 25.3 kcal/mol in cyclohexane. The potential energy surface is unusual; the rotational transition state 9a-rot-ts connects directly to the orthogonal transition state for ring-closure 9aTS. The decoupling of rotational and pseudopericyclic bond-forming transition states is contrasted with the single pericyclic transition state (15TS) for the electrocyclic ring-opening of oxetene (15) to acrolein (16). For comparison, the calculated homolytic strength of the N-NO bond is 40.0 kcal/mol (MP4(SDQ, FC)/6-31G* + ZPE).
- Bartsch,Yeh Moon Chae,Ham,Birney
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p. 7479 - 7486
(2007/10/03)
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