6402-09-1Relevant articles and documents
4-Phosphoryl Pyrazolones for Highly Selective Lithium Separation from Alkali Metal Ions
Du, Hao,Hennersdorf, Felix,Lindoy, Leonard F.,Schaper, Gerrit,Steup, Johannes,Weigand, Jan J.,Wenzel, Marco,Zhang, Jianfeng,Zheng, Shili
supporting information, (2021/11/10)
Effective receptors for the separation of Li+ from a mixture with other alkali metal ions under mild conditions remains an important challenge that could benefit from new approaches. In this study, it is demonstrated that the 4-phosphoryl pyrazolones, HL2-HL4, in the presence of the typical industrial organophosphorus co-ligands tributylphosphine oxide (TBPO), tributylphosphate (TBP) and trioctylphosphine oxide (TOPO), are able to selectively recognise and extract lithium ions from aqueous solution. Structural investigations in solution as well as in the solid state reveal the existence of a series of multinuclear Li+ complexes that include dimers (TBPO, TBP) as well as rarely observed trimers (TOPO) and represent the first clear evidence for the synergistic role of the co-ligands in the extraction process. Our findings are supported by detailed NMR, MS and extraction studies. Liquid-liquid extraction in the presence of TOPO revealed an unprecedented high Li+ extraction efficiency (78 %) for HL4 compared to the use of the industrially employed acylpyrazolone HL1 (15 %) and benzoyl-1,1,1-trifluoroacetone (52 %) extractants. In addition, a high selectivity for Li+ over Na+, K+ and Cs+ under mild conditions (pH ～8.2) confirms that HL2-HL4 represent a new class of ligands that are very effective extractants for use in lithium separation.
Rhodium-Catalyzed [4+2] Annulation of N-Aryl Pyrazolones with Diazo Compounds To Access Pyrazolone-Fused Cinnolines
Dhole, Sandip,Huang, Wan-Wen,Huang, Ying-Ti,Lin, Chih-Yu,Sun, Chung-Ming
supporting information, p. 4984 - 4992 (2021/09/28)
An efficient synthesis of novel dinitrogen-fused heterocycles such as pyrazolo[1,2-a]cinnoline derivatives have been accomplished by the rhodium(III)-catalyzed reaction of N-arylpyrazol-5-ones with α-diazo compounds. This reaction proceeds through a cascade C?H activation/intramolecular cyclization with a broad substrate scope. Furthermore, this protocol is successfully extended to the unusual phosphorus-containing α-diazo compounds and cyclic diazo compounds as the cross-coupling partners to deliver the two new kinds of pyrazolo[1,2-a]cinnolinones. The control experiments were performed to reveal insight into the mechanism of this reaction, involving reversible C?H activation, migratory insertion of the diazo compound, and cascade cyclization as the key steps of the transformation. Moreover, gram-scale synthesis and further transformation of the target product demonstrate the synthetic utility of the present protocol.
Metal-Free Direct C–H Thiolation and Thiocyanation of Pyrazolones
Kittikool, Tanakorn,Yotphan, Sirilata
supporting information, (2020/02/13)
Metal-free approach for direct C–H thiolation and thiocyanation of N-substituted pyrazolones with disulfides and thiocyanate salts, respectively, are developed. These reactions allow the C–S bond coupling to proceed effectively under mild conditions, providing useful and convenient methods for preparation of a series of 4-thio-substituted pyrazolone analogues, which have potential applications in organic, medicinal and material chemistry. Preliminary mechanistic investigation suggested that radical processes are likely to involve in these transformations.
