Highly Regioselective Nickel-Catalyzed Cross-Coupling of <i>N</i>-Tosylaziridines and Alkylzinc Reagents
作者:Kim L. Jensen、Eric A. Standley、Timothy F. Jamison
DOI:10.1021/ja505823s
日期:2014.8.6
ligand-controlled, nickel-catalyzed cross-coupling of aliphatic N-tosylaziridines with aliphatic organozinc reagents. The reaction protocol displays complete regioselectivity for reaction at the less hindered C-N bond, and the products are furnished in good to excellent yield for a broad selection of substrates. Moreover, we have developed an air-stablenickel(II) chloride/ligand precatalyst that can be handled and
A General Strategy for the Synthesis of Enantiomerically Pure Azetidines and Aziridines through Nickel-Catalyzed Cross-Coupling
作者:Kim L. Jensen、Dennis U. Nielsen、Timothy F. Jamison
DOI:10.1002/chem.201500886
日期:2015.5.11
expanded this concept to the synthesis of enantiomerically pure, terminal alkyl aziridines. Coupling of a TMS‐protected aziridine alcohol, followed by acidic work‐up to remove the silyl group, provides 1,2‐amino alcohol products that are readily cyclized to aziridines. Both of these sequences display excellent functional group tolerance and deliver the desired azetidine and aziridine products in good to excellent
Synthesis and in Vitro Evaluation of 5-[<sup>18</sup>F]Fluoroalkyl Pyrimidine Nucleosides for Molecular Imaging of Herpes Simplex Virus Type 1 Thymidine Kinase Reporter Gene Expression
作者:Ann-Marie Chacko、Wenchao Qu、Hank F. Kung
DOI:10.1021/jm800501d
日期:2008.9.25
Two novel series of 5-fluoroalkyl-2'-deoxyuridines (FPrDU, FBuDU, FPeDU) and 2'-fluoro-2'-deoxy-5-fluoroalkylarabinouridines (FFPrAU, FFBuAU, FFPeAU) that have three, four, or five methylene units (propyl, butyl, or pentyl) at C-5 were prepared and tested as reporter probes for imaging herpes simplex virus type I thymidine kinase (HSV1-tk) gene expression. The Negishi coupling methodology was employed in efficiently synthesizing the radiolabeling precursors. All six 5-[F-18]fluoroalkyl pyrimidines were readily prepared from 3-N-benzoyl-3',5'-di-O-benzoyl-protected 5-O-mesylate Precursors in 17-35% radiochemical yield (decay-corrected). In vitro studies highlighted that all six [F-18]-labeled nucleosides selectively accumulated in cells expressing the HSV1-TK protein and there was negligible uptake in control cells. [F-18]FPrDU, [F-18]FBuDU, [F-18]FPeDU, and [F-18]FFBuAU had the best uptake profiles. Despite their selective accumulation in HSV1-tk-expressing cells, all 5-fluoroalkyl pyrimidine nucleosides had low-to-negligible cytotoxic activity (CC50 > 1000-1209 mu M). Ultimately, the results demonstrated that 5-[F-18]fluoropropyl, [F-18]fluorobutyl, and [F-18]fluoropentyl pyrimidine nucleosides have the potential to be in vivo HSV1-TK PET reporter probes over a dynamic range of reporter gene expression levels.
Cobalt Bromide-Catalyzed Negishi-Type Cross-Coupling of Amides