13093-02-2Relevant academic research and scientific papers
Anion-driven conformation control and enhanced sulfate binding utilising aryl linked salicylaldoxime dicopper helicates
Stevens, James R.,Plieger, Paul G.
, p. 12235 - 12241 (2011)
The synthesis and spectroscopic analysis of both "metal-only" and anion encapsulated dicopper(ii) double helicates utilising a new 1,4-aryl spacer is described. X-Ray crystallographic analysis of the complexes reveal that the aromatic spacer increases rig
Selective Synthesis of Bisdimethylamine Derivatives from Diols and an Aqueous Solution of Dimethylamine through Iridium-Catalyzed Borrowing Hydrogen Pathway
Jeong, Jaeyoung,Fujita, Ken-ichi
, (2021/12/13)
Bisdimethylamine derivatives are an important class of compounds in the polymer and pharmaceutical industries. However, existing methods for the synthesis of these compounds have several drawbacks such as low selectivity, use of toxic reagents, and generation of waste. In this study, a new system was developed for the selective synthesis of bisdimethylamine derivatives using a diol and dimethylamine as starting materials and an iridium complex bearing an N-heterocyclic carbene ligand as catalyst. The starting materials were easily available, less toxic, inexpensive, and easy to handle. The reaction proceeded efficiently through a borrowing hydrogen pathway under aqueous conditions, without any additional organic solvent, to afford various bisdimethylamine derivatives in good to excellent yields.
Substrate Specificity in Ester Hydrolysis by a New Water-Soluble Heterocyclophane
Tabushi, Iwao,Kimura, Yoshio,Yamamura, Kazuo
, p. 6486 - 6492 (2007/10/02)
A new water-soluble heterocyclophane, N,N,N',N',N'',N'',N''',N'''-octamethyl-2,11,20,29-tetraazaparacyclophanetetrammonium tetrafluoroborate (1), was found to catalyze the hydrolysis reaction of three aromatic chloroacetates, ClCH2CO2R , very effectively and specifically.The rate accelerations judged from the rate constant ratio of k2/k0 were 25+/-3 (7c), 6+/-0.5 (7b), or 2.6 (7a) at pH 8.10 in phosphate buffer and 18+/-2 (7c), 11+/-1 (7b), or 2.4 (7a) at pH 6.96 in phosphate buffer, strongly indicating that the "inclusion-electrostatic" catalyst 1 is more effective and discriminating than any of CTAB micelle, simple cyclodextrin inclusion, or an open-chain analogue (9).Very interestingly, however, a unique inhibition by 1 was found with a substrate of the α-chloro-β-naphthyl type (14), showing a rate constant ratio of kinh/k0=0.084+/-0.023 (1/12 deceleration).In order to elucidate the basis of this interesting discriminative catalysis or inhibition by 1, mechanistic studies were carried out.Temperature-jump experiments by the use of a model compound for substrate, sodium hydroxynaphthalenecarboxylate (11,12), had shown that the present host-guest inclusions are satisfactorily fast (kA=1.8E7 to 4.4E7 s-1 M-1; kD=1.6E4 to 3.8E4 s-1), allowing the host and guest to search for the most appropriate arrangement for the slow subsequent hydrolysis.The absence of any systematic correlation between log (k2/k0) vs. pKa of the leaving phenol or naphthol or a small basicity dependence of the N+-aryloxyl interaction leads to the conclusion that the very discriminative catalysis by 1 was developed mostly from specific substrate binding, in a sense that the N+-oxyanion interaction, at the transition state for the tetrahedral intermediate formation, remarkably depends on the substrate structure.The one-twelfth deceleration observed for 14 was, therefore, attributed to the inhibition of this N+-oxyanion interaction due to either the mechanism of "reverse binding" of the substrate or the "induced disfit".
