1198183-95-7Relevant articles and documents
Aryl imidazylates and aryl sulfates as electrophiles in metal-free ArSN1 reactions
Qrareya, Hisham,Protti, Stefano,Fagnoni, Maurizio
, p. 11527 - 11533 (2015/01/16)
Some oxygen-bonded substituents were investigated as leaving groups in photoinduced ArSN1 reactions. Irradiation of aryl imidazylates and of the corresponding imidazolium salts mainly caused homolysis of the ArO-S bond. However, previously unexplored trifluoroethoxy aryl sulfates were found to undergo efficient metal-free arylation. The sulfates were conveniently generated in situ by dissolving the corresponding imidazolium salts in basic 2,2,2-trifluoroethanol.
Microwave-promoted copper-free Sonogashira-Hagihara couplings of aryl imidazolylsulfonates in water
Civicos, Jose F.,Alonso, Diego A.,Najera, Carmen
supporting information, p. 203 - 208 (2013/03/14)
Aryl imidazol-1-ylsulfonates have been efficiently cross-coupled with aryl-, alkyl-, and silylacetylenes in neat water under copper-free conditions at 110 °C assisted by microwave irradiation. Using 0.5mol% of an oxime palladacycle as precatalyst, 2-dicyclohexylphosphino-2′,6′- dimethoxybiphenyl (SPhos, 2mol%) as ligand, hexadecyltrimethylammonium bromide (CTAB) as additive, and triethylamine (TEA) as base, a wide array of disubstituted alkynes has been prepared in good to high yields in only 30min. Copyright
Preparation of trifluoroethyl- and phenyl-protected sulfates using sulfuryl imidazolium salts
Desoky, Ahmed Y.,Hendel, Jennifer,Ingram, Laura,Taylor, Scott Douglas
supporting information; experimental part, p. 1281 - 1287 (2011/03/23)
Sulfuryl imidazolium salts (SIS's), a new class of sulfating agents, were prepared bearing the trifluoroethyl (TFE) and phenyl groups, two functionalities that have been used for the protection of sulfate monoesters, by subjecting the corresponding sulfonyl imidazoles with methyl triflate. In contrast, SIS's bearing the electron donating neopentyl and isobutyl groups, two moieties that have also been used for the protection of sulfates, were found to be unstable and could not be isolated though SIS's bearing electron donating aryl groups, such as a p-methoxyphenyl or p-thiomethylphenyl group were readily prepared and are stable compounds. In most instances, TFE-protected phenolic and carbohydrate sulfates were obtained in good yield by reaction of the corresponding SIS's with steroids and carbohydrates. Phenyl-protected carbohydrates were also readily prepared using the corresponding SIS's. Those SIS's having a methyl group at the 2-position of the imidazole ring were, in general, superior sulfating agents to those, which lacked a methyl group at this position. The use of SIS's to prepare TFE-protected sulfates represents a significant improvement of the previous reported procedure, which involved treating unprotected sulfates with trifluorodiazoethane. The TFE protecting group was removed from steroidal sulfates and secondary sulfates in carbohydrates in high yields using NaN3 in warm DMF, conditions that are less vigorous than those previously reported for removing this group. Deprotection of TFE-protected 6-sulfated carbohydrates using NaN3 in warm DMF proceeded in lower yields due to partial desulfation.
