Synthesis of <sup>18</sup>F-difluoromethylarenes using aryl boronic acids, ethyl bromofluoroacetate and [<sup>18</sup>F]fluoride
作者:Jeroen B. I. Sap、Thomas C. Wilson、Choon Wee Kee、Natan J. W. Straathof、Christopher W. am Ende、Paramita Mukherjee、Lei Zhang、Christophe Genicot、Véronique Gouverneur
DOI:10.1039/c8sc05096a
日期:——
Herein, we report the radiosynthesis of 18F-difluoromethylarenes via the assembly of three components, a boron reagent, ethyl bromofluoroacetate, and cyclotron-produced non-carrier added [18F]fluoride. The two key steps are a copper-catalysed cross-coupling reaction, and a Mn-mediated 18F-fluorodecarboxylation.
Electrochemical Carboxylation of α,α-Difluorotoluene Derivatives and Its Application to the Synthesis of α-Fluorinated Nonsteroidal Anti-Inflammatory Drugs
Electrochemical carboxylation of α,α-difluorotoluene derivatives resulted in an efficient fixation of carbon dioxide to give the corresponding α-fluorophenylacetic acids in good yields, and this reaction was successfully applied to the synthesis of α-fluorinated nonsteroidal anti-inflammatory drugs (NSAIDs).
AbstractDeveloping novel catalysts with potent activity is of great importance in organocatalysis. In this study, we designed and prepared a new class of benzotetramisole Lewis base catalysts (AxBTM) that have both central and axial chirality. This unique feature of these catalysts results in a three‐dimensional microenvironment with multi‐layers of chirality. The performance of the developed catalysts was tested in a series of cycloaddition reactions. These included the AxBTM‐catalyzed (2+2) cycloaddition between α‐fluoro‐α‐aryl anhydride with imines or oxindoles, and the sequential gold/AxBTM‐catalyzed (4+2) cycloaddition of enynamides with pentafluorophenyl esters. The interplay between axial and central chirality had a collaborative effect in regulating the stereochemistry in these cycloadditions, leading to high levels of stereoselectivity that would otherwise be challenging to achieve using conventional BTM catalysts. However, the (2+2) and (4+2) cycloadditions have different predilections for axial and central chirality combinations.
Silver-Mediated 18F-Labeling of Aryl-CF3 and Aryl-CHF2 with 18F-Fluoride
[18F]arylCF3 and [18F]arylCHF2 derivatives from arylCF2Br and arylCHFCl precursors applying a silver-mediated halogenexchange with [18F]fluoride. In the absence of Ag(I)OTf, no reaction takes place at room temperature for both classes of substrates; this result demonstrates the beneficial role of silver(I) as a means to induce 18F-incorporation under very mild conditions.