1. Improved, Odorless Access to Benzo[1,2-d;4,5-d']- bis[1,3]dithioles and Tert-butyl Arylsulfides via C-S Cross Coupling
Kevin Kopp, Olav Schiemann, Nico Fleck Molecules. 2020 Aug 12;25(16):3666. doi: 10.3390/molecules25163666.
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.
2. Cardiac regeneration by direct reprogramming in this decade and beyond
Hiroyuki Yamakawa, Masaki Ieda Inflamm Regen. 2021 Jul 1;41(1):20. doi: 10.1186/s41232-021-00168-5.
Japan faces an increasing incidence of heart disease, owing to a shift towards a westernized lifestyle and an aging demographic. In cases where conventional interventions are not appropriate, regenerative medicine offers a promising therapeutic option. However, the use of stem cells has limitations, and therefore, "direct cardiac reprogramming" is emerging as an alternative treatment. Myocardial regeneration transdifferentiates cardiac fibroblasts into cardiomyocytes in situ.Three cardiogenic transcription factors: Gata4, Mef2c, and Tbx5 (GMT) can induce direct reprogramming of fibroblasts into induced cardiomyocytes (iCMs), in mice. However, in humans, additional factors, such as Mesp1 and Myocd, are required. Inflammation and immune responses hinder the reprogramming process in mice, and epigenetic modifiers such as TET1 are involved in direct cardiac reprogramming in humans. The three main approaches to improving reprogramming efficiency are (1) improving direct cardiac reprogramming factors, (2) improving cell culture conditions, and (3) regulating epigenetic factors. miR-133 is a potential candidate for the first approach. For the second approach, inhibitors of TGF-β and Wnt signals, Akt1 overexpression, Notch signaling pathway inhibitors, such as DAPT ((S)-tert-butyl 2-((S)-2-(2-(3,5-difluorophenyl) acetamido) propanamido)-2-phenylacetate), fibroblast growth factor (FGF)-2, FGF-10, and vascular endothelial growth factor (VEGF: FFV) can influence reprogramming. Reducing the expression of Bmi1, which regulates the mono-ubiquitination of histone H2A, alters histone modification, and subsequently the reprogramming efficiency, in the third approach. In addition, diclofenac, a non-steroidal anti-inflammatory drug, and high level of Mef2c overexpression could improve direct cardiac reprogramming.Direct cardiac reprogramming needs improvement if it is to be used in humans, and the molecular mechanisms involved remain largely elusive. Further advances in cardiac reprogramming research are needed to bring us closer to cardiac regenerative therapy.
3. (S)-tert-Butyl 3-(3-phenyl-1,2,4-oxa-diazol-5-yl)piperidine-1-carboxyl-ate
Lin Liu, Guangxin Xia, Xuejun Liu, Jieshu Xie, Jingkang Shen Acta Crystallogr Sect E Struct Rep Online. 2010 Jun 5;66(Pt 7):o1576. doi: 10.1107/S1600536810018714.
The title compound, C(18)H(23)N(3)O(3), crystallized with two independent mol-ecules (A and B) in the asymmetric unit. The phenyl ring and the 1,2,4-oxadiazole ring are inclined to one another by 19.9 (3)° in mol-ecule A and 7.3 (3)° in mol-ecule B. The absolute structure of the title compound was referred to the transfered chiral center (S) of one of the starting reacta-nts. In the crystal, A mol-ecules are linked by C-H⋯N inter-actions involving the two oxadiazole N atoms.
