1621691-73-3Relevant academic research and scientific papers
Bimodal concentration-dependent reactivity pattern of a glycosyl donor: Is the solution structure involved?
Kononov, Leonid O.,Fedina, Ksenia G.,Orlova, Anna V.,Kondakov, Nikolay N.,Abronina, Polina I.,Podvalnyy, Nikita M.,Chizhov, Alexander O.
, p. 28 - 35 (2017)
Changes in concentration (0.001–0.1?M) of an arabinofuranosyl donor (1) have been shown to modulate the temperature T at which activation of 1 occurs (from??23?°C to?+7?°C), the reaction time (from 1.5?h to 3 days) and the yield of the disaccharide formed (from 14% to 82%). At concentrations exceeding 0.01?M, these parameters, as well as the specific optical rotation of the solution of 1, virtually do not depend on concentration suggesting formation of reacting species (supramers) of glycosyl donor with similar structures, hence reactivities, but considerably different from those formed in more dilute solutions. The found critical concentration (0.01?M) separates two concentration ranges of reaction solutions corresponding to two types of solution structure that are featured by the presence of fundamentally different supramers of glycosyl donor, which have distinct chemical properties. These results allow a fresh look at the problems of reactivity of chemical compounds and selectivity of the reactions in which they participate.
The use of O-trifluoroacetyl protection and profound influence of the nature of glycosyl acceptor in benzyl-free arabinofuranosylation
Abronina, Polina I.,Fedina, Ksenia G.,Podvalnyy, Nikita M.,Zinin, Alexander I.,Chizhov, Alexander O.,Kondakov, Nikolay N.,Torgov, Vladimir I.,Kononov, Leonid O.
, p. 25 - 36 (2014/08/18)
The influence of O-trifluoroacetyl (TFA) groups at different positions of thioglycoside glycosyl donors on stereoselectivity of α- arabinofuranosylation leading to corresponding disaccharides was studied. It was shown that TFA group in thioglycoside glycosyl donors, when combined with 2-O-(triisopropylsilyl) (TIPS) non-participating group, may be regarded as an electron-withdrawing protecting group that may enhance 1,2-cis-selectivity in arabinofuranosylation, the results strongly depending on the nature of glycosyl acceptor. The reactivities of the glycosyl donors were compared with those of a similar thioglycoside with O-pentafluoropropionyl groups and the known phenyl 3,5-O-(di-tert-butylsilylene)-1-thio-α-d-arabinofuranosides with 2-O-TIPS and 2-O-benzyl groups. The 'matching' in the donor-acceptor combination was found to be critical for achieving both high reactivity of glycosyl donor and β-stereoselectivity of arabinofuranosylation. The use of glycosyl donors with TFA and silyl protection may be useful in the realization of the benzyl-free approach to oligoarabinofuranosides with azido group in aglycon - convenient building blocks for the preparation of neoglycoconjugates.
