1233032-09-1Relevant articles and documents
Colorimetric and luminescent sensors for chloride: Hydrogen bonding vs deprotonation
Elmes, Robert B. P.,Turner, Peter,Jolliffe, Katrina A.
, p. 5638 - 5641 (2013)
The synthesis and photophysical properties of four squaramide based fluorescent anion sensors (1-4) are described. These luminescent compounds showed selectivity for Cl- over various other anions with concomitant changes in both their UV/visible and fluorescence properties upon Cl - addition, attributed to initial H-bonding followed by NH deprotonation in the presence of excess Cl-, signaled by a color change. The nature of the electron withdrawing aryl substituents is directly related to the H-bonding ability/acidity of the squaramide protons and can be used to tune the deprotonation behavior.
Synthesis and biological effect of lysosome-targeting fluorescent anion transporters with enhanced anionophoric activity
Hong, Xiao-Qiao,He, Xiang-Yu,Tam, Kin Yip,Chen, Wen-Hua
, (2020)
Two lysosome-targeting fluorescent anion transporters derived from coumarins, trifluoromethylated arylsquaramides and morpholines were synthesized, and their specificity and efficiency to target and alkalize lysosomes were investigated. They are able to target lysosomes specifically. Compared with the previous analogue without trifluoromethyl substituents, these two conjugates, in particular the one having a 3,5-bis(trifluoromethyl) substituent, exhibit significantly higher ability to facilitate the transport of chloride anions, alkalize lysosomes and reduce the activity of lysosomal Cathepsin B enzyme. The present finding suggests that improving the anionophoric activity of lysosome-targeting fluorescent anion transporters is favorable to the efficiency to alkalize lysosomes and deactivate lysosomal Cathepsin B enzyme.
Enantioselective conjugate addition of pyrazolones to nitroalkenes catalyzed by chiral squaramide organocatalyst
Aydin, Alime Ebru,Culha, Selda
, p. 106 - 114 (2021)
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Highly enantioselective one-pot sequential synthesis of valerolactones and pyrazolones bearing all-carbon quaternary stereocentres
Xu, Yan-Li,Qin, Zhou-Zhou,Wang, Yu-Xia,Zhao, Peng-Fei,Li, Hong-Feng,Du, Zhi-Hong,Da, Chao-Shan
, p. 1610 - 1615 (2021)
Highly enantiopure and bioactive δ-valerolactones and pyrazolones, bearing α-all-carbon quaternary stereocentres, were successfully and sequentially preparedviaa one-pot procedure starting from readily available, inexpensive materials, catalysed by a new chiral squaramide under mild reaction conditions. An organocatalytic Michael reaction afforded the valerolactones, while a one-pot Michael-hydrazinolysis-imidization cascade yielded the pyrazolones. This procedure is economically efficient and environmentally benign.
Squaramide–Quaternary Ammonium Salt as an Effective Binary Organocatalytic System for Oxazolidinone Synthesis from Isocyanates and Epoxides
Rostami, Ali,Ebrahimi, Amirhossein,Husband, John,Anwar, Muhammad Usman,Csuk, Rene,Al-Harrasi, Ahmed
, p. 1881 - 1895 (2020/03/13)
Squaramide–quaternary ammonium salt is illustrated as a simple, tunable, and competent metal-free binary catalytic platform for the atom-economic conversion of epoxides and isocyanates into oxazolidinones. Although, various metal catalysts have been employed for the title reaction, application of organocatalysis is scarce. At first, a rational survey of catalytic activity of several air-stable and architecturally distinct squaramides was undertaken. Thereafter, the impact on catalytic capability of different parameters, such as temperature, catalyst loading, and nature of nucleophiles, was examined. This binary organocatalytic system for the oxazolidinone synthesis, composed of a squaramide entity along with a suitable halide anion, was applied to the challenging conversion of a plethora of alkyl- and aryl-substituted epoxides– including disubstituted and enantioenriched ones– and isocyanates into the corresponding oxazolidinones in high-to-excellent yields. The time-dependent formation of oxazolidinone from epoxide and isocyanate was monitored by FTIR-ATR and 1H NMR spectroscopy and the scalability of this process was also described. In light of 1H NMR experiment, a hydrogen-bonding/anion-binding mechanism was proposed wherein the nucleophilic ring-opening operation, and oxo- and carbamate-anions stabilization occur cooperatively towards isocyanate fixation.