1
|
Kopp K, Schiemann O, Fleck N. Improved, Odorless Access to Benzo[1,2-d;4,5-d']- bis[1,3]dithioles and Tert-butyl Arylsulfides via C-S Cross Coupling. Molecules 2020; 25:molecules25163666. [PMID: 32806560 PMCID: PMC7464442 DOI: 10.3390/molecules25163666] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 08/07/2020] [Accepted: 08/11/2020] [Indexed: 11/26/2022] Open
Abstract
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.
Collapse
|
2
|
Frank J, Elewa M, Said MM, El Shihawy HA, El-Sadek M, Müller D, Meister A, Hause G, Drescher S, Metz H, Imming P, Mäder K. Synthesis, Characterization, and Nanoencapsulation of Tetrathiatriarylmethyl and Tetrachlorotriarylmethyl (Trityl) Radical Derivatives—A Study To Advance Their Applicability as in Vivo EPR Oxygen Sensors. J Org Chem 2015; 80:6754-66. [PMID: 26020133 DOI: 10.1021/acs.joc.5b00918] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Tissue oxygenation plays an important role in the pathophysiology of various diseases and is often a marker of prognosis and therapeutic response. EPR (ESR) is a suitable noninvasive oximetry technique. However, to reliably deploy soluble EPR probes as oxygen sensors in complex biological systems, there is still a need to investigate and improve their specificity, sensitivity, and stability. We reproducibly synthesized various derivatives of tetrathiatriarylmethyl and tetrachlorotriarylmethyl (trityl) radicals. Hydrophilic radicals were investigated in aqueous solution mimicking physiological conditions by, e.g., variation of viscosity and ionic strength. Their specificity was satisfactory, but the oxygen sensitivity was low. To enhance the capability of trityl radicals as oxygen sensors, encapsulation into oily core nanocapsules was performed. Thus, different lipophilic triesters were prepared and characterized in oily solution employing oils typically used in drug formulations, i.e., middle-chain triglycerides and isopropyl myristate. Our screening identified the deuterated ethyl ester of D-TAM (radical 13) to be suitable. It had an extremely narrow single EPR line under anoxic conditions and excellent oxygen sensitivity. After encapsulation, it retained its oxygen responsiveness and was protected against reduction by ascorbic acid. These biocompatible and highly sensitive nanosensors offer great potential for future EPR oximetry applications in preclinical research.
Collapse
Affiliation(s)
- Juliane Frank
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Marwa Elewa
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany.,‡Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt
| | - Mohamed M Said
- ‡Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt
| | - Hosam A El Shihawy
- ‡Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt
| | | | - Diana Müller
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Annette Meister
- ⊥Center for Structure and Dynamics of Proteins (MZP), Biocenter Martin-Luther-Universität (MLU) Halle-Wittenberg, Weinbergweg 22, 06120 Halle (Saale), Germany
| | - Gerd Hause
- #Biocenter Martin-Luther-Universität (MLU) Halle-Wittenberg, Weinbergweg 22, 06120 Halle (Saale), Germany
| | - Simon Drescher
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Hendrik Metz
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Peter Imming
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Karsten Mäder
- †Institut für Pharmazie, Martin-Luther-Universität (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| |
Collapse
|