43183-55-7Relevant academic research and scientific papers
Taming Ambident Triazole Anions: Regioselective Ion Pairing Catalyzes Direct N-Alkylation with Atypical Regioselectivity
Dale, Harvey J.A.,Hodges, George R.,Lloyd-Jones, Guy C.
supporting information, p. 7181 - 7193 (2019/05/10)
Controlling the regioselectivity of ambident nucleophiles toward alkylating agents is a fundamental problem in heterocyclic chemistry. Unsubstituted triazoles are particularly challenging, often requiring inefficient stepwise protection-deprotection strategies and prefunctionalization protocols. Herein we report on the alkylation of archetypal ambident 1,2,4-triazole, 1,2,3-triazole, and their anions, analyzed by in situ 1H/19F NMR, kinetic modeling, diffusion-ordered NMR spectroscopy, X-ray crystallography, highly correlated coupled-cluster computations [CCSD(T)-F12, DF-LCCSD(T)-F12, DLPNO-CCSD(T)], and Marcus theory. The resulting mechanistic insights allow design of an organocatalytic methodology for ambident control in the direct N-alkylation of unsubstituted triazole anions. Amidinium and guanidinium receptors are shown to act as strongly coordinating phase-transfer organocatalysts, shuttling triazolate anions into solution. The intimate ion pairs formed in solution retain the reactivity of liberated triazole anions but, by virtue of highly regioselective ion pairing, exhibit alkylation selectivities that are completely inverted (1,2,4-triazole) or substantially enhanced (1,2,3-triazole) compared to the parent anions. The methodology allows direct access to 4-alkyl-1,2,4-triazoles (rr up to 94:6) and 1-alkyl-1,2,3-triazoles (rr up to 99:1) in one step. Regioselective ion pairing acts in effect as a noncovalent in situ protection mechanism, a concept that may have broader application in the control of ambident systems.
Azacyclo-dicarbene subunit borane ionic liquid and preparation method thereof
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Paragraph 0037; 0040, (2018/07/30)
The invention relates to an azacyclo-dicarbene subunit borane ionic liquid and a preparation method thereof. The azacyclo-dicarbene subunit borane ionic liquid has a structural formula I as shown in the specification. A method for preparing the compound of formula I comprises the following main steps: performing an alkylation reaction on 1,2,4-triazole and a carbonic ester compound, further performing a quaternary amination reaction with halogenated hydrocarbon, and finally performing a reaction with sodium borohydride, thereby obtaining a target product. The ionic liquid provided by the invention can be used as a self-combustion type green rocket propellant, and has the advantages of being short in ignition delay time, good in water stability, large in density ratio impact value, and thelike. In the formula I, R1 is selected from any one of alkyl, and R2 is selected from any one of hydrocarbyl substituent groups.
Spin-transition behaviour in chains of FeII bridged by 4-substituted 1,2,4-triazoles carrying alkyl tails
Roubeau,Alcazar Gomez,Balskus,Kolnaar,Haasnoot,Reedijk
, p. 144 - 150 (2007/10/03)
A family of polymeric 1-dimensional chains of iron(II) species showing the spin-crossover phenomenon has been synthesized using 4-n-alkyl-1,2,4-triazoles as bridging ligands. The influence of the length of the alkyl tails on the triazole ligands on characteristic features of the spin transition was studied, showing degrading of steepness with increasing length. A set of four counter ions has been used to access a wider range of transition temperatures. Large hysteresis loops are detected with small tails, mainly for the methyl and ethyl substituted products. In most cases longer tails weaken co-operativity and hysteresis gradually decreases to zero. However it is shown that with certain anions hysteresis remains, even with very long tails on the triazoles. Weakening of the co-operativity mainly arises from a diminution of the length of the polymeric chains with increasing alkyl tails on the triazole. This effect is anion dependent. A strong interaction along the polymeric chains is confirmed.
An investigation into the alkylation of 1,2,4-triazole
Bulger, Paul G.,Cottrell, Ian F.,Cowden, Cameron J.,Davies, Antony J.,Dolling, Ulf-H.
, p. 1297 - 1301 (2007/10/03)
The alkylation of 1,2,4-triazole with 4-nitrobenzyl halides and a variety of bases afforded the 1- and 4-alkylated isomers with a consistent regioselectivity of 90:10. Previously reported regiospecific alkylations of 1,2,4-triazole were re-examined and the quoted isomer ratios were shown to depend on the isolation procedure. The use of DBU as base in the alkylation of 1,2,4-triazole allows for a convenient and high yielding synthesis of 1- substituted-1,2,4-triazoles. (C) 2000 Elsevier Science Ltd.
