title: A theoretical insight into the formation mechanisms of C/N-ribonucleosides with pyrimidine and ribose.
abstract: The detailed formation mechanisms of C-ribonucleoside and N-ribonucleoside via the reaction of 2,4,6-triaminopyrimidine (TAP) with (d)-ribose in aqueous solution were explored using density functional theory (DFT). The calculations indicate that five isomers (α,β-furanose, α,β-pyranose and open-chain aldehyde) of (d)-ribose can exist in equilibrium in aqueous solution. In contrast to cyclic isomers, an open-chain aldehyde is most feasible to react with TAP. In general, the formation pathways of C-nucleoside and N-nucleoside proceed in three steps including nucleophilic addition, dehydration and cyclization. The calculated apparent activation energies are 28.8 kcal mol-1and 29.2 kcal mol-1, respectively. It suggests that both C- and N-nucleoside can be formed in aqueous solution, which is in good agreement with the experimental results. The water molecule plays an important "H-bridge" role by the hydrogen atom relay. Finally, a model structure of nucleobase, which will be beneficial for the C-C glycosidic bond formation, is proposed.
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan 250014, P. R. China. fanghuang@sdnu.edu.cn dchen@sdnu.edu.cn.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Wang
authors.forename: Fang
authors.initials: F
authors.lastname: Huang
authors.forename: Chuanzhi
authors.initials: C
authors.lastname: Sun
authors.forename: Jianbiao
authors.initials: J
authors.lastname: Liu
authors.forename: Xiehuang
authors.initials: X
authors.lastname: Sheng
authors.forename: Dezhan
authors.initials: D
authors.lastname: Chen
mesh_terms: D002244:Carbon / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry; D011743:Pyrimidines / Q000737:chemistry* / Q000378:metabolism; D012263:Ribonucleosides / Q000737:chemistry* / Q000378:metabolism; D012266:Ribose / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D011743:Pyrimidines; D012263:Ribonucleosides; D014867:Water; C012070:2,4,6-triaminopyrimidine; D012266:Ribose; D002244:Carbon; D009584:Nitrogen