RESUMO
A variety of long-lived carbocations containing the p-(pentafluorosulfanyl)phenyl and m-(pentafluorosulfanyl)phenyl groups have been characterized by low-temperature NMR spectroscopy. In the case of potential nonclassical carbocations substituted with the p-(pentafluorosulfanyl)phenyl substituent, deviations from linearity when the Hammett parameter (σC+) is plotted versus 13C NMR shifts of the carbocationic center were observed. Plotting the experimentally derived 13C NMR shifts versus σC+ or σ+ of classical 4-phenyl-X substituted carbocations also provides a means to accurately back-calculate the σ+ and σC+ parameters of the -SF5 substituent.
RESUMO
[This corrects the article DOI: 10.1039/C8RA09296F.].
RESUMO
A new 19F NMR method is presented which can be used to detect weak protein binding of small molecules with up to mM affinity. The method capitalizes on the synthetic availability of unique SF5 containing compounds and the generation of five-quantum coherences (5QC). Given the high sensitivity of 5QC relaxation to exchange events (i.e. reversible protein binding) fragments which bind to the target with weak affinity can be identified. The utility of the method in early stage drug discovery programs is demonstrated with applications to two model proteins, the neurotoxic NGAL and the prominent tumor target ß-catenin.
RESUMO
Pyridine promotes dediazoniation of aryldiazonium tetrafluoroborates. The formed aryl radicals were trapped with B2pin2, iodine, or tetrahydrofuran to afford boronic esters, iodobenzenes and benzenes, respectively. The application to the synthesis of (pentafluorosulfanyl)phenylboronic esters, iodo(pentafluorosulfanyl)benzenes and (pentafluorosulfanyl)benzene is shown.
RESUMO
Diethyl 2-nitro-(pentafluorosulfanyl)benzylphosphonates, available by the vicarious nucleophilic substitution reaction of meta- and para-nitro-(pentafluorosulfanyl)benzenes and diethyl chloromethylphosphonate, undergo Horner-Wadsworth-Emmons reaction with aldehydes in the presence of potassium hydroxide in acetonitrile at ambient temperature to give (E)-2-nitro-1-alkenyl-(pentafluorosulfanyl)benzenes in good yields and high stereoselectivities. Follow-up transformations of the primary products provided (E)-1-alkenyl-(pentafluorosulfanyl)benzenes and 2-(2-arylethyl)-(pentafluorosulfanyl)anilines.
RESUMO
Vicarious nucleophilic substitutions (VNS) of hydrogen in 1-nitro-4-(pentafluorosulfanyl)benzene with carbanions provide 2-substituted 1-nitro-4-(pentafluorosulfanyl)benzenes in good to high yields. VNS of 1-nitro-3-(pentafluorosulfanyl)benzene gives a mixture of 6- and 4-substituted 1-nitro-3-(pentafluorosulfanyl)benzenes in 85:15 to >98:2 ratio and good to high yields. In basic media, the VNS reactions lead to the formation of carbanions that can be alkylated by alkyl halides affording the corresponding alkylated products in moderate yields. Transformation of primary products to substituted (pentafluorosulfanyl)anilines and 3- or 4-substituted (pentafluorosulfanyl)benzenes is also described.
RESUMO
Nucleophilic aromatic substitution of the nitro group of para- and meta-nitro-(pentafluorosulfanyl)benzene with alkoxides and thiolates generates a range of substituted 4- and 3-(pentafluorosulfanyl)benzenes in a single-step reaction.