447463-65-2Relevant articles and documents
Improved, odorless access to Benzo[1,2-d;4,5-d′]-bis[1,3]dithioles and tert-butyl arylsulfides via C-S cross coupling
Fleck, Nico,Kopp, Kevin,Schiemann, Olav
, (2020/09/17)
Benzo[1,2-d;4,5-d′]bis[1,3]dithioles are important building blocks within a range of functional materials such as fluorescent dyes, conjugated polymers, and stable trityl radicals. Access to these is usually gained via tert-butyl aryl sulfides, the synthesis of which requires the use of highly malodorous tert-butyl thiol and relies on SNAr-chemistry requiring harsh reaction conditions, while giving low yields. In the present work, S-tert-butyl isothiouronium bromide is successfully applied as an odorless surrogate for tert-butyl thiol. The C-S bond formation is carried out under palladium catalysis with the thiolate formed in situ resulting in high yields of tert-butyl aryl sulfides. The subsequent formation of benzo[1,2-d;4,5-d′]bis[1,3]dithioles is here achieved with scandium(III)triflate, a less harmful reagent than the usually used Lewis acids, e.g., boron trifluoride or tetrafluoroboric acid. This enables a convenient and environmentally more compliant access to high yields of benzo[1,2-d;4,5-d′]bis[1,3]dithioles.
Trityl Radicals with a Combination of the Orthogonal Functional Groups Ethyne and Carboxyl: Synthesis without a Statistical Step and EPR Characterization
Hintz, Henrik,Vanas, Agathe,Klose, Daniel,Jeschke, Gunnar,Godt, Adelheid
, p. 3304 - 3320 (2019/03/11)
Finland trityl radical (FTR) shows very attractive EPR spectroscopic properties for a manifold of applications. For most of its applications only one chemically reactive functional group is needed. The presence of three equally reactive carboxyl groups leads to FTR modifications through reactions which give statistical mixtures of 1-fold-, 2-fold-, and 3-fold-modified and unmodified FTR. To avoid the side effects of such a statistical reaction - limited yields and separation challenges - we took a route to FTR-type trityl radicals with scaffold assembly by addition of an aryllithium with one type of substituent to a diarylketone with another type of substituent. This gave the two FTR-type trityl radicals 1 and 2 which carry a combination of the chemically orthogonal groups, carboxyl and triisopropylsilylethynyl. Standard column chromatography was sufficient for product isolation on all stages, whereby polar tagging helped. The EPR spectroscopic properties of the trityl radicals 1 and 2 in ethanol were determined in X and W bands. Their g anisotropy and T1 and T2 relaxation times make them spin labels as good as the benchmark FTR. This paper discloses also details on the synthesis of building blocks used for FTR preparation and improved access to the bare FTR scaffold.
TRIARYLMETHYL RADICALS
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Page/Page column 11, (2014/02/15)
New radical compounds, useful in the field of MRI imaging of formula (I). The radical compounds are in particular new triarylmethyl ("trityl") radicals which can be used as polarizing agents for polarizing a molecule in the DNP process.