期刊
JOURNAL OF FLUORINE CHEMISTRY
卷 131, 期 12, 页码 1327-1337出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jfluchem.2010.09.003
关键词
2,3,4,5,6-Pentafluorobiphenyl; meso-5,10,15,20-Tetrakis-(pentafluorophenyl)-porphyrin; Nucleophilic substitution; Computational chemistry; Meisenheimer complex; Tetrahedral S(N)2 mechanism
资金
- Grant Agency of the Czech Republic [203/01/1311]
- Ministry of Education of the Czech Republic [MSM 6046137301]
2,3,4,5,6-Pentafluorobiphenyl (PFBi) was modified by the nucleophilic substitution of one fluorine using a series of 0-, S- and N-nucleophiles, viz, alkaline salts of 2,2,2-trifluoro-ethanol, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctanol, 1,2:3,4-di-O-isopropylidenexylitol, allylsulfane, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctane-1-thiol, 3-aminopropan-1-ol (7), and tert-butyl N-(3-aminopropyl)carbamate (8). All the substitutions took place exclusively at the position para to the phenyl group. (3-Amino-propyl)amino derivative of PFBi (15) was further modified at the terminal amino group by acylation or fluoroalkylation. The reaction of 8 was applied to meso-5,10,15,20-tetrakis-(pentafluorophenyl)porphyrin (20) to afford tris- (21) and tetrakis-substituted (22) products with complete para-regioselectivity. Theoretical studies of the reaction pathways of PFBi with ammonia, microsolvated lithium fluoride or lithium hydroxide revealed that no Meisenheimer-type intermediates are formed in the course of the simulated reactions: instead, tetrahedral S(N)2 mechanism was found. Significant regioselectivity of the nucleophilic aromatic substitution, leading to 4-substituted products, was predicted based on relative transition state energies in agreement with the observed experimental results. (C) 2010 Elsevier BM. All rights reserved.
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